xrender fix

Signed-off-by: Yuxuan Shui <yshuiv7@gmail.com>

.clang-tidy

@@ -23,5 +23,9 @@ CheckOptions:
     value: 255.0;1.0;
   - key: readability-function-cognitive-complexity.IgnoreMacros
     value: true
+  - key: readability-function-cognitive-complexity.Threshold
+    value: 50
   - key: readability-function-cognitive-complexity.DescribeBasicIncrements
     value: true
+  - key: bugprone-signed-char-misuse.CharTypdefsToIgnore
+    value: int8_t

.gitignore

@@ -16,6 +16,7 @@ compton
 build/
 compile_commands.json
 build.ninja
+make.sh
 
 # language servers
 .ccls-cache

README.md

@@ -85,12 +85,23 @@ $ ninja -C build
 
 ### To install
 
+#### AUR (arch)
+- picom-ftlabs-git
+Thanks to @Fxzzi for maintaining the package.
+
+
 ``` bash
 $ ninja -C build install
 ```
 
 Default install prefix is `/usr/local`, you can change it with `meson configure -Dprefix=<path> build`
 
+## Running
+To launch with all animations as a background process you can use:
+`picom --animations -b`
+
+To only have specific animations, enable them with cli flags (see `picom --help`) or add them to your picom config.
+
 ## How to Contribute
 
 All contributions are welcome!

picom.sample.conf

@@ -1,29 +1,76 @@
+#################################
+#           Animations         #
+
+# !These animations WILL NOT work correctly for any other wm other than phyOS-dwm fork!
+
+# fly-in: Windows fly in from random directions to the screen
+# maximize: Windows pop from center of the screen to their respective positions
+# minimize: Windows minimize from their position to the center of the screen
+# slide-in-center: Windows move from upper-center of the screen to their respective positions
+# slide-out-center: Windows move to the upper-center of the screen
+# slide-left: Windows are created from the right-most window position and slide leftwards
+# slide right: Windows are created from the left-most window position and slide rightwards
+# slide-down: Windows are moved from the top of the screen and slide downward
+# slide-up: Windows are moved from their position to top of the screen
+# squeeze: Windows are either closed or created to/from their center y-position (the animation is similar to a blinking eye)
+# squeeze-bottom: Similar to squeeze, but the animation starts from bottom-most y-position
+# zoom: Windows are either created or destroyed from/to their center (not the screen center)
+
+#################################
+
+#enable or disable animations
+animations = true;
+#change animation speed of windows in current tag e.g open window in current tag
+animation-stiffness-in-tag = 125;
+#change animation speed of windows when tag changes
+animation-stiffness-tag-change = 90.0;
+
+animation-window-mass = 0.4;
+animation-dampening = 15;
+animation-clamping = true;
+
+#open windows
+animation-for-open-window = "zoom";
+#minimize or close windows
+animation-for-unmap-window = "squeeze";
+#popup windows
+animation-for-transient-window = "slide-up"; #available options: slide-up, slide-down, slide-left, slide-right, squeeze, squeeze-bottom, zoom
+
+#set animation for windows being transitioned out while changings tags
+animation-for-prev-tag = "minimize";
+#enables fading for windows being transitioned out while changings tags
+enable-fading-prev-tag = true;
+
+#set animation for windows being transitioned in while changings tags
+animation-for-next-tag = "slide-in-center";
+#enables fading for windows being transitioned in while changings tags
+enable-fading-next-tag = true;
+
 #################################
 #             Shadows           #
 #################################
 
-
 # Enabled client-side shadows on windows. Note desktop windows
 # (windows with '_NET_WM_WINDOW_TYPE_DESKTOP') never get shadow,
 # unless explicitly requested using the wintypes option.
 #
 # shadow = false
-shadow = true;
+shadow = false;
 
 # The blur radius for shadows, in pixels. (defaults to 12)
 # shadow-radius = 12
-shadow-radius = 7;
+shadow-radius = 60;
 
 # The opacity of shadows. (0.0 - 1.0, defaults to 0.75)
 # shadow-opacity = .75
 
 # The left offset for shadows, in pixels. (defaults to -15)
 # shadow-offset-x = -15
-shadow-offset-x = -7;
+shadow-offset-x = -20;
 
 # The top offset for shadows, in pixels. (defaults to -15)
 # shadow-offset-y = -15
-shadow-offset-y = -7;
+shadow-offset-y = -20;
 
 # Red color value of shadow (0.0 - 1.0, defaults to 0).
 # shadow-red = 0
@@ -48,6 +95,9 @@ shadow-exclude = [
   "class_g = 'Conky'",
   "class_g ?= 'Notify-osd'",
   "class_g = 'Cairo-clock'",
+  "class_g = 'dwm'",
+  "class_g = 'chromium'",
+  "class_g *?= 'slop'",
   "_GTK_FRAME_EXTENTS@:c"
 ];
 
@@ -73,19 +123,18 @@ shadow-exclude = [
 
 # Fade windows in/out when opening/closing and when opacity changes,
 #  unless no-fading-openclose is used.
-# fading = false
 fading = true;
 
 # Opacity change between steps while fading in. (0.01 - 1.0, defaults to 0.028)
 # fade-in-step = 0.028
-fade-in-step = 0.03;
+fade-in-step = 0.023;
 
 # Opacity change between steps while fading out. (0.01 - 1.0, defaults to 0.03)
 # fade-out-step = 0.03
-fade-out-step = 0.03;
+fade-out-step = 0.035;
 
 # The time between steps in fade step, in milliseconds. (> 0, defaults to 10)
-# fade-delta = 10
+fade-delta = 10
 
 # Specify a list of conditions of windows that should not be faded.
 # fade-exclude = []
@@ -104,15 +153,13 @@ fade-out-step = 0.03;
 
 # Opacity of inactive windows. (0.1 - 1.0, defaults to 1.0)
 # inactive-opacity = 1
-inactive-opacity = 0.8;
 
 # Opacity of window titlebars and borders. (0.1 - 1.0, disabled by default)
 # frame-opacity = 1.0
-frame-opacity = 0.7;
 
 # Let inactive opacity set by -i override the '_NET_WM_WINDOW_OPACITY' values of windows.
 # inactive-opacity-override = true
-inactive-opacity-override = false;
+inactive-opacity-override = true;
 
 # Default opacity for active windows. (0.0 - 1.0, defaults to 1.0)
 # active-opacity = 1.0
@@ -122,21 +169,13 @@ inactive-opacity-override = false;
 
 # Specify a list of conditions of windows that should never be considered focused.
 # focus-exclude = []
-focus-exclude = [ "class_g = 'Cairo-clock'" ];
+focus-exclude = [
+"class_g = 'Cairo-clock'" ,
+];
 
 # Use fixed inactive dim value, instead of adjusting according to window opacity.
 # inactive-dim-fixed = 1.0
 
-# Specify a list of opacity rules, in the format `PERCENT:PATTERN`,
-# like `50:name *= "Firefox"`. picom-trans is recommended over this.
-# Note we don't make any guarantee about possible conflicts with other
-# programs that set '_NET_WM_WINDOW_OPACITY' on frame or client windows.
-# example:
-#    opacity-rule = [ "80:class_g = 'URxvt'" ];
-#
-# opacity-rule = []
-
-
 #################################
 #           Corners             #
 #################################
@@ -144,52 +183,21 @@ focus-exclude = [ "class_g = 'Cairo-clock'" ];
 # Sets the radius of rounded window corners. When > 0, the compositor will
 # round the corners of windows. Does not interact well with
 # `transparent-clipping`.
-corner-radius = 0
+corner-radius = 11;
 
 # Exclude conditions for rounded corners.
-rounded-corners-exclude = [
-  "window_type = 'dock'",
-  "window_type = 'desktop'"
-];
+#rounded-corners-exclude = [
+#  "window_type = 'dock'",
+#  "window_type = 'desktop'"
+#];
 
-
-#################################
-#     Background-Blurring       #
-#################################
-
-
-# Parameters for background blurring, see the *BLUR* section for more information.
-# blur-method =
-# blur-size = 12
-#
-# blur-deviation = false
-#
-# blur-strength = 5
-
-# Blur background of semi-transparent / ARGB windows.
-# Bad in performance, with driver-dependent behavior.
-# The name of the switch may change without prior notifications.
-#
-# blur-background = false
-
-# Blur background of windows when the window frame is not opaque.
-# Implies:
-#    blur-background
-# Bad in performance, with driver-dependent behavior. The name may change.
-#
-# blur-background-frame = false
-
-
-# Use fixed blur strength rather than adjusting according to window opacity.
-# blur-background-fixed = false
-
-
-# Specify the blur convolution kernel, with the following format:
-# example:
-#   blur-kern = "5,5,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1";
-#
-# blur-kern = ""
-blur-kern = "3x3box";
+blur: {
+  method = "dual_kawase";
+  strength = 9;
+  background = true;
+  background-frame = false;
+  background-fixed = false;
+}
 
 
 # Exclude conditions for background blur.
@@ -197,24 +205,25 @@ blur-kern = "3x3box";
 blur-background-exclude = [
   "window_type = 'dock'",
   "window_type = 'desktop'",
-  "_GTK_FRAME_EXTENTS@:c"
+  "_GTK_FRAME_EXTENTS@:c",
+  "class_g = 'Chromium'",
+  "class_g = 'Discord'",
+  "class_g = 'Dunst'",
+  "class_g = 'Peek'",
+  "class_g *?= 'slop'",
 ];
 
 #################################
 #       General Settings        #
 #################################
 
-# Enable remote control via D-Bus. See the man page for more details.
-# dbus = true
-
 # Daemonize process. Fork to background after initialization. Causes issues with certain (badly-written) drivers.
 # daemon = false
 
 # Specify the backend to use: `xrender`, `glx`, `egl` or `xr_glx_hybrid`.
 # `xrender` is the default one.
 #
-# backend = "glx"
-backend = "xrender";
+backend = "glx"
 
 # Use higher precision during rendering, and apply dither when presenting the
 # rendered screen. Reduces banding artifacts, but might cause performance
@@ -222,8 +231,7 @@ backend = "xrender";
 dithered-present = false;
 
 # Enable/disable VSync.
-# vsync = false
-vsync = true;
+# vsync = true
 
 # Try to detect WM windows (a non-override-redirect window with no
 # child that has 'WM_STATE') and mark them as active.
@@ -239,25 +247,25 @@ mark-ovredir-focused = true;
 # shaped windows. The accuracy is not very high, unfortunately.
 #
 # detect-rounded-corners = false
-detect-rounded-corners = true;
+detect-rounded-corners = false;
 
 # Detect '_NET_WM_WINDOW_OPACITY' on client windows, useful for window managers
 # not passing '_NET_WM_WINDOW_OPACITY' of client windows to frame windows.
 #
 # detect-client-opacity = false
-detect-client-opacity = true;
+detect-client-opacity = false;
 
 # Use EWMH '_NET_ACTIVE_WINDOW' to determine currently focused window,
 # rather than listening to 'FocusIn'/'FocusOut' event. Might have more accuracy,
 # provided that the WM supports it.
 #
-# use-ewmh-active-win = false
+use-ewmh-active-win = true;
 
 # Unredirect all windows if a full-screen opaque window is detected,
 # to maximize performance for full-screen windows. Known to cause flickering
 # when redirecting/unredirecting windows.
 #
-# unredir-if-possible = false
+unredir-if-possible = false;
 
 # Delay before unredirecting the window, in milliseconds. Defaults to 0.
 # unredir-if-possible-delay = 0
@@ -301,7 +309,7 @@ detect-transient = true;
 # practically happened) and may not work with blur-background.
 # My tests show a 15% performance boost. Recommended.
 #
-# glx-no-stencil = false
+glx-no-stencil = true;
 
 # GLX backend: Avoid rebinding pixmap on window damage.
 # Probably could improve performance on rapid window content changes,
@@ -322,24 +330,18 @@ use-damage = true;
 # calls are finished before picom starts drawing. Needed on nvidia-drivers
 # with GLX backend for some users.
 #
-# xrender-sync-fence = false
+xrender-sync-fence = true;
 
-# GLX backend: Use specified GLSL fragment shader for rendering window
-# contents. Read the man page for a detailed explanation of the interface.
+# GLX backend: Use specified GLSL fragment shader for rendering window contents.
+# See `compton-default-fshader-win.glsl` and `compton-fake-transparency-fshader-win.glsl`
+# in the source tree for examples.
 #
-# window-shader-fg = "default"
-
-# Use rules to set per-window shaders. Syntax is SHADER_PATH:PATTERN, similar
-# to opacity-rule. SHADER_PATH can be "default". This overrides window-shader-fg.
-#
-# window-shader-fg-rule = [
-#   "my_shader.frag:window_type != 'dock'"
-# ]
+window-shader-fg = "default";
 
 # Force all windows to be painted with blending. Useful if you
 # have a glx-fshader-win that could turn opaque pixels transparent.
 #
-# force-win-blend = false
+# force-win-blend = true;
 
 # Do not use EWMH to detect fullscreen windows.
 # Reverts to checking if a window is fullscreen based only on its size and coordinates.
@@ -356,7 +358,7 @@ use-damage = true;
 # Make transparent windows clip other windows like non-transparent windows do,
 # instead of blending on top of them.
 #
-# transparent-clipping = false
+transparent-clipping = false;
 
 # Specify a list of conditions of windows that should never have transparent
 # clipping applied. Useful for screenshot tools, where you need to be able to
@@ -429,3 +431,9 @@ wintypes:
   popup_menu = { opacity = 0.8; }
   dropdown_menu = { opacity = 0.8; }
 };
+
+opacity-rule = [
+  "100:class_g = 'St' && focused",
+  "50:class_g = 'St' && !focused",
+  "100:fullscreen",
+];

src/atom.c

@@ -2,12 +2,20 @@
 #include <xcb/xcb.h>
 
 #include "atom.h"
+#include "cache.h"
 #include "common.h"
-#include "utils.h"
+#include "compiler.h"
 #include "log.h"
+#include "utils.h"
 
-static inline void *atom_getter(void *ud, const char *atom_name, int *err) {
-	xcb_connection_t *c = ud;
+struct atom_entry {
+	struct cache_handle entry;
+	xcb_atom_t atom;
+};
+
+static inline int atom_getter(struct cache *cache attr_unused, const char *atom_name,
+                              struct cache_handle **value, void *user_data) {
+	xcb_connection_t *c = user_data;
 	xcb_intern_atom_reply_t *reply = xcb_intern_atom_reply(
 	    c, xcb_intern_atom(c, 0, to_u16_checked(strlen(atom_name)), atom_name), NULL);
 
@@ -18,9 +26,32 @@ static inline void *atom_getter(void *ud, const char *atom_name, int *err) {
 		free(reply);
 	} else {
 		log_error("Failed to intern atoms");
-		*err = 1;
+		return -1;
 	}
-	return (void *)(intptr_t)atom;
+
+	struct atom_entry *entry = ccalloc(1, struct atom_entry);
+	entry->atom = atom;
+	*value = &entry->entry;
+	return 0;
+}
+
+static inline void
+atom_entry_free(struct cache *cache attr_unused, struct cache_handle *handle) {
+	struct atom_entry *entry = cache_entry(handle, struct atom_entry, entry);
+	free(entry);
+}
+
+xcb_atom_t get_atom(struct atom *a, const char *key, xcb_connection_t *c) {
+	struct cache_handle *entry = NULL;
+	if (cache_get_or_fetch(&a->c, key, &entry, c, atom_getter) < 0) {
+		log_error("Failed to get atom %s", key);
+		return XCB_NONE;
+	}
+	return cache_entry(entry, struct atom_entry, entry)->atom;
+}
+
+xcb_atom_t get_atom_cached(struct atom *a, const char *key) {
+	return cache_entry(cache_get(&a->c, key), struct atom_entry, entry)->atom;
 }
 
 /**
@@ -28,11 +59,15 @@ static inline void *atom_getter(void *ud, const char *atom_name, int *err) {
  */
 struct atom *init_atoms(xcb_connection_t *c) {
 	auto atoms = ccalloc(1, struct atom);
-	atoms->c = new_cache((void *)c, atom_getter, NULL);
-#define ATOM_GET(x)                                                                      \
-	atoms->a##x = (xcb_atom_t)(intptr_t)cache_get_or_fetch(atoms->c, #x, NULL)
+	atoms->c = CACHE_INIT;
+#define ATOM_GET(x) atoms->a##x = get_atom(atoms, #x, c)
 	LIST_APPLY(ATOM_GET, SEP_COLON, ATOM_LIST1);
 	LIST_APPLY(ATOM_GET, SEP_COLON, ATOM_LIST2);
 #undef ATOM_GET
 	return atoms;
 }
+
+void destroy_atoms(struct atom *a) {
+	cache_invalidate_all(&a->c, atom_entry_free);
+	free(a);
+}

src/atom.h

@@ -1,6 +1,4 @@
 #pragma once
-#include <stdlib.h>
-
 #include <xcb/xcb.h>
 
 #include "cache.h"
@@ -53,23 +51,18 @@
 
 #define ATOM_DEF(x) xcb_atom_t a##x
 
+struct atom_entry;
 struct atom {
-	struct cache *c;
+	struct cache c;
 	LIST_APPLY(ATOM_DEF, SEP_COLON, ATOM_LIST1);
 	LIST_APPLY(ATOM_DEF, SEP_COLON, ATOM_LIST2);
 };
 
-struct atom *init_atoms(xcb_connection_t *);
+/// Create a new atom object with a xcb connection. `struct atom` does not hold
+/// a reference to the connection.
+struct atom *init_atoms(xcb_connection_t *c);
 
-static inline xcb_atom_t get_atom(struct atom *a, const char *key) {
-	return (xcb_atom_t)(intptr_t)cache_get_or_fetch(a->c, key, NULL);
-}
+xcb_atom_t get_atom(struct atom *a, const char *key, xcb_connection_t *c);
+xcb_atom_t get_atom_cached(struct atom *a, const char *key);
 
-static inline xcb_atom_t get_atom_cached(struct atom *a, const char *key) {
-	return (xcb_atom_t)(intptr_t)cache_get(a->c, key);
-}
-
-static inline void destroy_atoms(struct atom *a) {
-	cache_free(a->c);
-	free(a);
-}
+void destroy_atoms(struct atom *a);

src/backend/backend.c

@@ -56,6 +56,58 @@ region_t get_damage(session_t *ps, bool all_damage) {
 	return region;
 }
 
+static void process_window_for_painting(session_t *ps, struct managed_win *w,
+                                        void *win_image, double additional_alpha,
+                                        region_t *reg_bound, region_t *reg_visible,
+                                        region_t *reg_paint, region_t *reg_paint_in_bound) {
+	// For window image processing, we don't have to limit the process
+	// region to damage for correctness. (see <damager-note> for
+	// details)
+
+	// The visible region, in window local coordinates Although we
+	// don't limit process region to damage, we provide that info in
+	// reg_visible as a hint. Since window image data outside of the
+	// damage region won't be painted onto target
+	coord_t window_coord = {.x = w->g.x, .y = w->g.y};
+	coord_t dest_coord = {.x = w->g.x + w->widthb, .y = w->g.y + w->heightb};
+
+	region_t reg_visible_local;
+	region_t reg_bound_local;
+	{
+		// The bounding shape, in window local coordinates
+		pixman_region32_init(&reg_bound_local);
+		pixman_region32_copy(&reg_bound_local, reg_bound);
+		pixman_region32_translate(&reg_bound_local, -w->g.x, -w->g.y);
+
+		pixman_region32_init(&reg_visible_local);
+		pixman_region32_intersect(&reg_visible_local, reg_visible, reg_paint);
+		pixman_region32_translate(&reg_visible_local, -w->g.x, -w->g.y);
+		// Data outside of the bounding shape won't be visible,
+		// but it is not necessary to limit the image operations
+		// to the bounding shape yet. So pass that as the visible
+		// region, not the clip region.
+		pixman_region32_intersect(&reg_visible_local, &reg_visible_local,
+		                          &reg_bound_local);
+	}
+
+	auto new_img = ps->backend_data->ops->clone_image(ps->backend_data, win_image,
+	                                                  &reg_visible_local);
+	auto reg_frame = win_get_region_frame_local_by_val(w);
+	double alpha = additional_alpha * w->opacity;
+	ps->backend_data->ops->set_image_property(
+	    ps->backend_data, IMAGE_PROPERTY_OPACITY, new_img, &alpha);
+	ps->backend_data->ops->image_op(ps->backend_data, IMAGE_OP_APPLY_ALPHA, new_img,
+	                                &reg_frame, &reg_visible_local,
+	                                (double[]){w->frame_opacity});
+	pixman_region32_fini(&reg_frame);
+	ps->backend_data->ops->compose(ps->backend_data, new_img,
+			       window_coord, NULL, dest_coord,
+			       reg_paint_in_bound, reg_visible, true);
+	ps->backend_data->ops->release_image(ps->backend_data, new_img);
+	pixman_region32_fini(&reg_visible_local);
+	pixman_region32_fini(&reg_bound_local);
+}
+
 void handle_device_reset(session_t *ps) {
 	log_error("Device reset detected");
 	// Wait for reset to complete
@@ -210,8 +262,8 @@ bool paint_all_new(session_t *ps, struct managed_win *const t) {
 
 	if (ps->root_image) {
 		ps->backend_data->ops->compose(ps->backend_data, ps->root_image,
-		                               (coord_t){0}, NULL, (coord_t){0},
-		                               &reg_paint, &reg_visible);
+		                               (coord_t){0}, NULL, (coord_t){.x = ps->root_width, .y = ps->root_height},
+		                               &reg_paint, &reg_visible, true);
 	} else {
 		ps->backend_data->ops->fill(ps->backend_data, (struct color){0, 0, 0, 1},
 		                            &reg_paint);
@@ -262,6 +314,7 @@ bool paint_all_new(session_t *ps, struct managed_win *const t) {
 		 * option */
 		auto real_win_mode = w->mode;
 		coord_t window_coord = {.x = w->g.x, .y = w->g.y};
+		coord_t dest_coord = {.x = w->g.x + w->widthb, .y = w->g.y + w->heightb};
 
 		if (w->blur_background &&
 		    (ps->o.force_win_blend || real_win_mode == WMODE_TRANS ||
@@ -390,7 +443,7 @@ bool paint_all_new(session_t *ps, struct managed_win *const t) {
 			}
 			ps->backend_data->ops->compose(
 			    ps->backend_data, w->shadow_image, shadow_coord,
-			    inverted_mask, window_coord, &reg_shadow, &reg_visible);
+			    inverted_mask, window_coord, &reg_shadow, &reg_visible, false);
 			if (inverted_mask) {
 				ps->backend_data->ops->set_image_property(
 				    ps->backend_data, IMAGE_PROPERTY_INVERTED,
@@ -434,6 +487,17 @@ bool paint_all_new(session_t *ps, struct managed_win *const t) {
 				ps->backend_data->ops->set_image_property(
 				    ps->backend_data, IMAGE_PROPERTY_BORDER_WIDTH,
 				    w->win_image, &border_width);
+				if (w->old_win_image) {
+					// TODO(dccsillag): explain why the following is
+					// "necessary"
+					double zero = 0.0;
+					ps->backend_data->ops->set_image_property(
+					    ps->backend_data, IMAGE_PROPERTY_BORDER_WIDTH,
+					    w->old_win_image, &zero);
+					ps->backend_data->ops->set_image_property(
+					    ps->backend_data, IMAGE_PROPERTY_CORNER_RADIUS,
+					    w->old_win_image, &zero);
+				}
 			}
 
 			ps->backend_data->ops->set_image_property(
@@ -456,53 +520,43 @@ bool paint_all_new(session_t *ps, struct managed_win *const t) {
 		}
 
 		// Draw window on target
-		if (w->frame_opacity == 1) {
+		bool is_animating = 0 <= w->animation_progress && w->animation_progress < 1.0;
+		if (w->frame_opacity == 1 && !is_animating) {
 			ps->backend_data->ops->compose(ps->backend_data, w->win_image,
-			                               window_coord, NULL, window_coord,
-			                               &reg_paint_in_bound, &reg_visible);
+			                               window_coord, NULL, dest_coord,
+			                               &reg_paint_in_bound, &reg_visible, true);
 		} else {
-			// For window image processing, we don't have to limit the process
-			// region to damage for correctness. (see <damager-note> for
-			// details)
+			if (is_animating && w->old_win_image) {
+				bool is_focused = win_is_focused_raw(w);
+				if (!is_focused && w->focused && w->opacity_is_set)
+					is_focused = true;
+				assert(w->old_win_image);
 
-			// The visible region, in window local coordinates Although we
-			// don't limit process region to damage, we provide that info in
-			// reg_visible as a hint. Since window image data outside of the
-			// damage region won't be painted onto target
-			region_t reg_visible_local;
-			region_t reg_bound_local;
-			{
-				// The bounding shape, in window local coordinates
-				pixman_region32_init(&reg_bound_local);
-				pixman_region32_copy(&reg_bound_local, &reg_bound);
-				pixman_region32_translate(&reg_bound_local, -w->g.x, -w->g.y);
+				bool resizing =
+					w->g.width != w->pending_g.width ||
+					w->g.height != w->pending_g.height;
 
-				pixman_region32_init(&reg_visible_local);
-				pixman_region32_intersect(&reg_visible_local,
-				                          &reg_visible, &reg_paint);
-				pixman_region32_translate(&reg_visible_local, -w->g.x,
-				                          -w->g.y);
-				// Data outside of the bounding shape won't be visible,
-				// but it is not necessary to limit the image operations
-				// to the bounding shape yet. So pass that as the visible
-				// region, not the clip region.
-				pixman_region32_intersect(
-				    &reg_visible_local, &reg_visible_local, &reg_bound_local);
+				// Only animate opacity here if we are resizing
+				// a transparent window
+				process_window_for_painting(ps, w, w->win_image,
+								is_focused ? 1.0 : w->opacity >= 1 ? 1.0 : w->animation_progress,
+								&reg_bound, &reg_visible,
+								&reg_paint, &reg_paint_in_bound);
+
+				// Only do this if size changes as otherwise moving
+				// transparent windows will flicker and if you just
+				// move so slightly they will keep flickering
+				if (resizing && (!is_focused || !w->opacity_is_set)) {
+					process_window_for_painting(ps, w, w->old_win_image,
+									1.0 - w->animation_progress,
+									&reg_bound, &reg_visible,
+									&reg_paint, &reg_paint_in_bound);
+				}
+			} else {
+				process_window_for_painting(
+				    ps, w, w->win_image, 1.0, &reg_bound, &reg_visible,
+				    &reg_paint, &reg_paint_in_bound);
 			}
-
-			auto new_img = ps->backend_data->ops->clone_image(
-			    ps->backend_data, w->win_image, &reg_visible_local);
-			auto reg_frame = win_get_region_frame_local_by_val(w);
-			ps->backend_data->ops->image_op(
-			    ps->backend_data, IMAGE_OP_APPLY_ALPHA, new_img, &reg_frame,
-			    &reg_visible_local, (double[]){w->frame_opacity});
-			pixman_region32_fini(&reg_frame);
-			ps->backend_data->ops->compose(ps->backend_data, new_img,
-			                               window_coord, NULL, window_coord,
-			                               &reg_paint_in_bound, &reg_visible);
-			ps->backend_data->ops->release_image(ps->backend_data, new_img);
-			pixman_region32_fini(&reg_visible_local);
-			pixman_region32_fini(&reg_bound_local);
 		}
 	skip:
 		pixman_region32_fini(&reg_bound);

src/backend/backend.h

@@ -181,7 +181,7 @@ struct backend_operations {
 	 */
 	void (*compose)(backend_t *backend_data, image_handle image, coord_t image_dst,
 	                image_handle mask, coord_t mask_dst, const region_t *reg_paint,
-	                const region_t *reg_visible) attr_nonnull(1, 2, 6, 7);
+	                const region_t *reg_visible, bool lerp) attr_nonnull(1, 2, 6, 7);
 
 	/// Fill rectangle of the rendering buffer, mostly for debug purposes, optional.
 	void (*fill)(backend_t *backend_data, struct color, const region_t *clip);

src/backend/dummy/dummy.c

@@ -68,7 +68,7 @@ static void dummy_check_image(struct backend_base *base, image_handle image) {
 void dummy_compose(struct backend_base *base, image_handle image, coord_t dst attr_unused,
                    image_handle mask attr_unused, coord_t mask_dst attr_unused,
                    const region_t *reg_paint attr_unused,
-                   const region_t *reg_visible attr_unused) {
+                   const region_t *reg_visible attr_unused, bool lerp attr_unused) {
 	auto dummy attr_unused = (struct dummy_data *)base;
 	dummy_check_image(base, image);
 	assert(mask == NULL || (struct backend_image *)mask == &dummy->mask);

src/backend/gl/gl_common.c

@@ -420,7 +420,7 @@ static void _gl_compose(backend_t *base, struct backend_image *img, GLuint targe
 	}
 
 	glUniform1i(win_shader->uniform_mask_tex, 2);
-	glUniform2f(win_shader->uniform_mask_offset, (float)mask_offset.x,
+	glUniform2f(win_shader->uniform_mask_offset, (float)mask_offset.x ,
 	            (float)mask_offset.y);
 	if (mask != NULL) {
 		glUniform1i(win_shader->uniform_mask_inverted, mask->color_inverted);
@@ -502,6 +502,7 @@ void x_rect_to_coords(int nrects, const rect_t *rects, coord_t image_dst,
 	image_dst.y = root_height - image_dst.y;
 	image_dst.y -= extent_height;
 
+
 	for (int i = 0; i < nrects; i++) {
 		// Y-flip. Note after this, crect.y1 > crect.y2
 		rect_t crect = rects[i];
@@ -551,11 +552,11 @@ void x_rect_to_coords(int nrects, const rect_t *rects, coord_t image_dst,
 }
 
 // TODO(yshui) make use of reg_visible
-void gl_compose(backend_t *base, image_handle image, coord_t image_dst,
-                image_handle mask_, coord_t mask_dst, const region_t *reg_tgt,
-                const region_t *reg_visible attr_unused) {
+void gl_compose(backend_t *base, image_handle image_data, coord_t image_dst, image_handle mask_,
+                coord_t mask_dst, const region_t *reg_tgt,
+                const region_t *reg_visible attr_unused, bool lerp) {
 	auto gd = (struct gl_data *)base;
-	auto img = (struct backend_image *)image;
+	auto img = (struct backend_image *)image_data;
 	auto mask = (struct backend_image *)mask_;
 	auto inner = (struct gl_texture *)img->inner;
 
@@ -580,6 +581,14 @@ void gl_compose(backend_t *base, image_handle image, coord_t image_dst,
 	coord_t mask_offset = {.x = mask_dst.x - image_dst.x, .y = mask_dst.y - image_dst.y};
 	x_rect_to_coords(nrects, rects, image_dst, inner->height, inner->height,
 	                 gd->height, inner->y_inverted, coord, indices);
+
+	if (lerp) {
+		for (unsigned int i = 2; i < 16; i+=4) {
+			coord[i+0] = lerp_range(0, mask_offset.x, 0, inner->width, coord[i+0]);
+			coord[i+1] = lerp_range(0, mask_offset.y, 0, inner->height, coord[i+1]);
+		}
+	}
+
 	_gl_compose(base, img, gd->back_fbo, mask, mask_offset, coord, indices, nrects);
 
 	free(indices);

src/backend/gl/gl_common.h

@@ -150,8 +150,8 @@ bool gl_last_render_time(backend_t *backend_data, struct timespec *time);
 /**
  * @brief Render a region with texture data.
  */
-void gl_compose(backend_t *, image_handle image, coord_t image_dst, image_handle mask,
-                coord_t mask_dst, const region_t *reg_tgt, const region_t *reg_visible);
+void gl_compose(backend_t *, image_handle image_data, coord_t image_dst, image_handle mask_,
+                coord_t mask_dst, const region_t *reg_tgt, const region_t *reg_visible, bool lerp);
 
 void gl_resize(struct gl_data *, int width, int height);
 

src/backend/xrender/xrender.c

@@ -14,6 +14,7 @@
 #include "backend/backend.h"
 #include "backend/backend_common.h"
 #include "common.h"
+#include "compiler.h"
 #include "config.h"
 #include "kernel.h"
 #include "log.h"
@@ -360,7 +361,7 @@ compose_impl(struct _xrender_data *xd, struct xrender_image *xrimg, coord_t dst,
 }
 
 static void compose(backend_t *base, image_handle image_, coord_t dst, image_handle mask_,
-                    coord_t mask_dst, const region_t *reg_paint, const region_t *reg_visible) {
+                    coord_t mask_dst, const region_t *reg_paint, const region_t *reg_visible, attr_unused bool lerp) {
 	struct _xrender_data *xd = (void *)base;
 	auto image = (struct xrender_image *)image_;
 	auto mask = (struct xrender_image *)mask_;

src/c2.c

@@ -1047,7 +1047,7 @@ static bool c2_l_postprocess(session_t *ps, c2_l_t *pleaf) {
 
 	// Get target atom if it's not a predefined one
 	if (pleaf->predef == C2_L_PUNDEFINED) {
-		pleaf->tgtatom = get_atom(ps->atoms, pleaf->tgt);
+		pleaf->tgtatom = get_atom(ps->atoms, pleaf->tgt, ps->c.c);
 		if (!pleaf->tgtatom) {
 			log_error("Failed to get atom for target \"%s\".", pleaf->tgt);
 			return false;
@@ -1509,7 +1509,8 @@ static inline void c2_match_once_leaf(session_t *ps, const struct managed_win *w
 		else {
 			char **strlst = NULL;
 			int nstr = 0;
-			if (wid_get_text_prop(ps, wid, pleaf->tgtatom, &strlst, &nstr)) {
+			if (wid_get_text_prop(&ps->c, ps->atoms, wid, pleaf->tgtatom,
+			                      &strlst, &nstr)) {
 				if (pleaf->index < 0 && nstr > 0 && strlen(strlst[0]) > 0) {
 					ntargets = to_u32_checked(nstr);
 					targets = (const char **)strlst;

src/cache.c

@@ -1,94 +1,43 @@
 #include <uthash.h>
 
-#include "compiler.h"
-#include "utils.h"
 #include "cache.h"
 
-struct cache_entry {
-	char *key;
-	void *value;
-	UT_hash_handle hh;
-};
-
-struct cache {
-	cache_getter_t getter;
-	cache_free_t free;
-	void *user_data;
-	struct cache_entry *entries;
-};
-
-static inline struct cache_entry *cache_get_entry(struct cache *c, const char *key) {
-	struct cache_entry *e;
+struct cache_handle *cache_get(struct cache *c, const char *key) {
+	struct cache_handle *e;
 	HASH_FIND_STR(c->entries, key, e);
 	return e;
 }
 
-void *cache_get(struct cache *c, const char *key) {
-	struct cache_entry *e = cache_get_entry(c, key);
-	return e ? e->value : NULL;
+int cache_get_or_fetch(struct cache *c, const char *key, struct cache_handle **value,
+                       void *user_data, cache_getter_t getter) {
+	*value = cache_get(c, key);
+	if (*value) {
+		return 0;
+	}
+
+	int err = getter(c, key, value, user_data);
+	assert(err <= 0);
+	if (err < 0) {
+		return err;
+	}
+	(*value)->key = strdup(key);
+
+	HASH_ADD_STR(c->entries, key, *value);
+	return 1;
 }
 
-void *cache_get_or_fetch(struct cache *c, const char *key, int *err) {
-	struct cache_entry *e = cache_get_entry(c, key);
-	if (e) {
-		return e->value;
-	}
-
-	int tmperr;
-	if (!err) {
-		err = &tmperr;
-	}
-
-	*err = 0;
-	e = ccalloc(1, struct cache_entry);
-	e->key = strdup(key);
-	e->value = c->getter(c->user_data, key, err);
-	if (*err) {
-		free(e->key);
-		free(e);
-		return NULL;
-	}
-
-	HASH_ADD_STR(c->entries, key, e);
-	return e->value;
-}
-
-static inline void cache_invalidate_impl(struct cache *c, struct cache_entry *e) {
-	if (c->free) {
-		c->free(c->user_data, e->value);
-	}
+static inline void
+cache_invalidate_impl(struct cache *c, struct cache_handle *e, cache_free_t free_fn) {
 	free(e->key);
 	HASH_DEL(c->entries, e);
-	free(e);
-}
-
-void cache_invalidate(struct cache *c, const char *key) {
-	struct cache_entry *e;
-	HASH_FIND_STR(c->entries, key, e);
-
-	if (e) {
-		cache_invalidate_impl(c, e);
+	if (free_fn) {
+		free_fn(c, e);
 	}
 }
 
-void cache_invalidate_all(struct cache *c) {
-	struct cache_entry *e, *tmpe;
+void cache_invalidate_all(struct cache *c, cache_free_t free_fn) {
+	struct cache_handle *e, *tmpe;
 	HASH_ITER(hh, c->entries, e, tmpe) {
-		cache_invalidate_impl(c, e);
+		cache_invalidate_impl(c, e, free_fn);
 	}
 }
-
-void *cache_free(struct cache *c) {
-	void *ret = c->user_data;
-	cache_invalidate_all(c);
-	free(c);
-	return ret;
-}
-
-struct cache *new_cache(void *ud, cache_getter_t getter, cache_free_t f) {
-	auto c = ccalloc(1, struct cache);
-	c->user_data = ud;
-	c->getter = getter;
-	c->free = f;
-	return c;
-}

src/cache.h

@@ -1,30 +1,43 @@
 #pragma once
 
+#include <uthash.h>
+#include "utils.h"
+
+#define cache_entry(ptr, type, member) container_of(ptr, type, member)
+
 struct cache;
+struct cache_handle;
 
-typedef void *(*cache_getter_t)(void *user_data, const char *key, int *err);
-typedef void (*cache_free_t)(void *user_data, void *data);
+/// User-provided function to fetch a value for the cache, when it's not present.
+/// Should return 0 if the value is fetched successfully, and a negative number if the
+/// value cannot be fetched. Getter doesn't need to initialize fields of `struct
+/// cache_handle`.
+typedef int (*cache_getter_t)(struct cache *, const char *key,
+                              struct cache_handle **value, void *user_data);
+typedef void (*cache_free_t)(struct cache *, struct cache_handle *value);
 
-/// Create a cache with `getter`, and a free function `f` which is used to free the cache
-/// value when they are invalidated.
-///
-/// `user_data` will be passed to `getter` and `f` when they are called.
-struct cache *new_cache(void *user_data, cache_getter_t getter, cache_free_t f);
+struct cache {
+	struct cache_handle *entries;
+};
+
+static const struct cache CACHE_INIT = {NULL};
+
+struct cache_handle {
+	char *key;
+	UT_hash_handle hh;
+};
 
 /// Get a value from the cache. If the value doesn't present in the cache yet, the
 /// getter will be called, and the returned value will be stored into the cache.
-void *cache_get_or_fetch(struct cache *, const char *key, int *err);
+/// Returns 0 if the value is already present in the cache, 1 if the value is fetched
+/// successfully, and a negative number if the value cannot be fetched.
+int cache_get_or_fetch(struct cache *, const char *key, struct cache_handle **value,
+                       void *user_data, cache_getter_t getter);
 
 /// Get a value from the cache. If the value doesn't present in the cache, NULL will be
 /// returned.
-void *cache_get(struct cache *, const char *key);
+struct cache_handle *cache_get(struct cache *, const char *key);
 
-/// Invalidate a value in the cache.
-void cache_invalidate(struct cache *, const char *key);
-
-/// Invalidate all values in the cache.
-void cache_invalidate_all(struct cache *);
-
-/// Invalidate all values in the cache and free it. Returns the user data passed to
-/// `new_cache`
-void *cache_free(struct cache *);
+/// Invalidate all values in the cache. After this call, `struct cache` holds no allocated
+/// memory, and can be discarded.
+void cache_invalidate_all(struct cache *, cache_free_t free_fn);

src/common.h

@@ -143,6 +143,11 @@ typedef struct session {
 	ev_timer unredir_timer;
 	/// Timer for fading
 	ev_timer fade_timer;
+	/// Timer for animations
+	ev_timer animation_timer;
+	/// Use an ev_idle callback for drawing
+	/// So we only start drawing when events are processed
+	ev_idle draw_idle;
 	/// Use an ev_timer callback for drawing
 	ev_timer draw_timer;
 	/// Called every time we have timeouts or new data on socket,
@@ -175,7 +180,6 @@ typedef struct session {
 	bool server_grabbed;
 	/// Width of root window.
 	int root_width;
-	/// Height of root window.
 	int root_height;
 	/// X Composite overlay window.
 	xcb_window_t overlay;
@@ -264,6 +268,13 @@ typedef struct session {
 	xcb_render_picture_t *alpha_picts;
 	/// Time of last fading. In milliseconds.
 	long long fade_time;
+	/// Time of last window animation step. In milliseconds.
+	long animation_time; // TODO(dccsillag) turn into `long long`, like fade_time
+	/// Head pointer of the error ignore linked list.
+	pending_reply_t *pending_reply_head;
+	/// Pointer to the <code>next</code> member of tail element of the error
+	/// ignore linked list.
+	pending_reply_t **pending_reply_tail;
 	// Cached blur convolution kernels.
 	struct x_convolution_kernel **blur_kerns_cache;
 	/// If we should quit

src/config.c

@@ -796,6 +796,10 @@ void set_default_winopts(options_t *opt, win_option_mask_t *mask, bool shadow_en
 			// opacity logic is complicated, and needs an "unset" state
 			opt->wintype_option[i].opacity = NAN;
 		}
+		if (!mask[i].animation) {
+			mask[i].animation = OPEN_WINDOW_ANIMATION_INVALID;
+			opt->wintype_option[i].animation = OPEN_WINDOW_ANIMATION_INVALID;
+		}
 		if (!mask[i].clip_shadow_above) {
 			mask[i].clip_shadow_above = true;
 			opt->wintype_option[i].clip_shadow_above = false;
@@ -803,6 +807,40 @@ void set_default_winopts(options_t *opt, win_option_mask_t *mask, bool shadow_en
 	}
 }
 
+enum open_window_animation parse_open_window_animation(const char *src) {
+	if (strcmp(src, "none") == 0) {
+		return OPEN_WINDOW_ANIMATION_NONE;
+	} else if (strcmp(src, "fly-in") == 0) {
+		return OPEN_WINDOW_ANIMATION_FLYIN;
+	} else if (strcmp(src, "zoom") == 0) {
+		return OPEN_WINDOW_ANIMATION_ZOOM;
+	} else if (strcmp(src, "slide-up") == 0) {
+		return OPEN_WINDOW_ANIMATION_SLIDE_UP;
+	} else if (strcmp(src, "slide-down") == 0) {
+		return OPEN_WINDOW_ANIMATION_SLIDE_DOWN;
+	} else if (strcmp(src, "slide-left") == 0) {
+		return OPEN_WINDOW_ANIMATION_SLIDE_LEFT;
+	} else if (strcmp(src, "slide-right") == 0) {
+		return OPEN_WINDOW_ANIMATION_SLIDE_RIGHT;
+	} else if (strcmp(src, "slide-out") == 0) {
+        return OPEN_WINDOW_ANIMATION_SLIDE_OUT;
+        } else if (strcmp(src, "slide-in") == 0) {
+        return OPEN_WINDOW_ANIMATION_SLIDE_IN;
+        } else if (strcmp(src, "slide-out-center") == 0) {
+            return OPEN_WINDOW_ANIMATION_SLIDE_OUT_CENTER;
+        } else if (strcmp(src, "slide-in-center") == 0) {
+            return OPEN_WINDOW_ANIMATION_SLIDE_IN_CENTER;
+        } else if (strcmp(src, "minimize") == 0 || strcmp(src, "maximize") == 0) {
+            return OPEN_WINDOW_ANIMATION_MINIMIZE;
+        } else if (strcmp(src, "squeeze") == 0) {
+            return OPEN_WINDOW_ANIMATION_SQUEEZE;
+        } else if (strcmp(src, "squeeze-bottom") == 0) {
+            return OPEN_WINDOW_ANIMATION_SQUEEZE_BOTTOM;
+        }
+
+	return OPEN_WINDOW_ANIMATION_INVALID;
+}
+
 char *parse_config(options_t *opt, const char *config_file, bool *shadow_enable,
                    bool *fading_enable, bool *hasneg, win_option_mask_t *winopt_mask) {
 	// clang-format off
@@ -848,6 +886,18 @@ char *parse_config(options_t *opt, const char *config_file, bool *shadow_enable,
 	    .no_fading_destroyed_argb = false,
 	    .fade_blacklist = NULL,
 
+	    .animations = false,
+	    .animation_for_open_window = OPEN_WINDOW_ANIMATION_NONE,
+	    .animation_for_transient_window = OPEN_WINDOW_ANIMATION_NONE,
+        .animation_for_unmap_window = OPEN_WINDOW_ANIMATION_NONE,
+        .animation_for_next_tag = OPEN_WINDOW_ANIMATION_NONE,
+        .animation_for_prev_tag = OPEN_WINDOW_ANIMATION_NONE,
+	    .animation_stiffness = 200.0,
+	    .animation_stiffness_tag_change = 200.0,
+	    .animation_window_mass = 1.0,
+	    .animation_dampening = 25,
+	    .animation_clamping = true,
+
 	    .inactive_opacity = 1.0,
 	    .inactive_opacity_override = false,
 	    .active_opacity = 1.0,
@@ -879,7 +929,8 @@ char *parse_config(options_t *opt, const char *config_file, bool *shadow_enable,
 
 	    .track_leader = false,
 
-	    .rounded_corners_blacklist = NULL
+	    .rounded_corners_blacklist = NULL,
+	    .animation_blacklist = NULL
 	};
 	// clang-format on
 

src/config.h

@@ -40,6 +40,24 @@ enum backend {
 	NUM_BKEND,
 };
 
+enum open_window_animation {
+	OPEN_WINDOW_ANIMATION_NONE = 0,
+	OPEN_WINDOW_ANIMATION_FLYIN,
+	OPEN_WINDOW_ANIMATION_SLIDE_UP,
+	OPEN_WINDOW_ANIMATION_SLIDE_DOWN,
+	OPEN_WINDOW_ANIMATION_SLIDE_LEFT,
+	OPEN_WINDOW_ANIMATION_SLIDE_RIGHT,
+	OPEN_WINDOW_ANIMATION_SLIDE_IN,
+	OPEN_WINDOW_ANIMATION_SLIDE_OUT,
+	OPEN_WINDOW_ANIMATION_SLIDE_IN_CENTER,
+	OPEN_WINDOW_ANIMATION_SLIDE_OUT_CENTER,
+	OPEN_WINDOW_ANIMATION_ZOOM,
+	OPEN_WINDOW_ANIMATION_MINIMIZE,
+	OPEN_WINDOW_ANIMATION_SQUEEZE,
+	OPEN_WINDOW_ANIMATION_SQUEEZE_BOTTOM,
+	OPEN_WINDOW_ANIMATION_INVALID,
+};
+
 typedef struct win_option_mask {
 	bool shadow : 1;
 	bool fade : 1;
@@ -49,6 +67,7 @@ typedef struct win_option_mask {
 	bool redir_ignore : 1;
 	bool opacity : 1;
 	bool clip_shadow_above : 1;
+	enum open_window_animation animation;
 } win_option_mask_t;
 
 typedef struct win_option {
@@ -60,6 +79,7 @@ typedef struct win_option {
 	bool redir_ignore;
 	double opacity;
 	bool clip_shadow_above;
+	enum open_window_animation animation;
 } win_option_t;
 
 enum blur_method {
@@ -195,6 +215,33 @@ typedef struct options {
 	/// Fading blacklist. A linked list of conditions.
 	c2_lptr_t *fade_blacklist;
 
+	// === Animations ===
+	/// Whether to do window animations
+	bool animations;
+	/// Which animation to run when opening a window
+	enum open_window_animation animation_for_open_window;
+	/// Which animation to run when opening a transient window
+	enum open_window_animation animation_for_transient_window;
+	/// Which animation to run when unmapping a window
+	enum open_window_animation animation_for_unmap_window;
+	/// Which animation to run when swapping to new tag
+	enum open_window_animation animation_for_next_tag;
+	/// Which animation to run for old tag
+	enum open_window_animation animation_for_prev_tag;
+	/// Spring stiffness for animation
+	double animation_stiffness;
+	/// Spring stiffness for current tag animation
+	double animation_stiffness_tag_change;
+	/// Window mass for animation
+	double animation_window_mass;
+	/// Animation dampening
+	double animation_dampening;
+	/// Whether to clamp animations
+	bool animation_clamping;
+	/// Animation blacklist. A linked list of conditions.
+	c2_lptr_t *animation_blacklist;
+	/// TODO: open/close animations
+
 	// === Opacity ===
 	/// Default opacity for inactive windows.
 	/// 32-bit integer with the format of _NET_WM_WINDOW_OPACITY.
@@ -278,6 +325,13 @@ typedef struct options {
 	// Make transparent windows clip other windows, instead of blending on top of
 	// them
 	bool transparent_clipping;
+
+	// Enable fading for next tag
+	bool enable_fading_next_tag;
+
+	// Enable fading for prev tag
+	bool enable_fading_prev_tag;
+
 	/// A list of conditions of windows to which transparent clipping
 	/// should not apply
 	c2_lptr_t *transparent_clipping_blacklist;
@@ -298,6 +352,7 @@ bool must_use parse_rule_window_shader(c2_lptr_t **, const char *, const char *)
 char *must_use locate_auxiliary_file(const char *scope, const char *path,
                                      const char *include_dir);
 enum blur_method must_use parse_blur_method(const char *src);
+enum open_window_animation must_use parse_open_window_animation(const char *src);
 
 /**
  * Add a pattern to a condition linked list.

src/config_libconfig.c

@@ -264,6 +264,15 @@ static inline void parse_wintype_config(const config_t *cfg, const char *member_
 			o->clip_shadow_above = ival;
 			mask->clip_shadow_above = true;
 		}
+        const char *sval = NULL;
+		if (config_setting_lookup_string(setting, "animation", &sval)) {
+			enum open_window_animation animation = parse_open_window_animation(sval);
+			if (animation >= OPEN_WINDOW_ANIMATION_INVALID)
+				animation = OPEN_WINDOW_ANIMATION_NONE;
+
+			o->animation = animation;
+			mask->animation = animation;
+		}
 
 		double fval;
 		if (config_setting_lookup_float(setting, "opacity", &fval)) {
@@ -514,6 +523,70 @@ char *parse_config_libconfig(options_t *opt, const char *config_file, bool *shad
 	parse_cfg_condlst(&cfg, &opt->shadow_clip_list, "clip-shadow-above");
 	// --fade-exclude
 	parse_cfg_condlst(&cfg, &opt->fade_blacklist, "fade-exclude");
+	// --animations
+	lcfg_lookup_bool(&cfg, "animations", &opt->animations);
+	// --animation-for-open-window
+	if (config_lookup_string(&cfg, "animation-for-open-window", &sval)) {
+		enum open_window_animation animation = parse_open_window_animation(sval);
+		if (animation >= OPEN_WINDOW_ANIMATION_INVALID) {
+			log_fatal("Invalid open-window animation %s", sval);
+			goto err;
+		}
+		opt->animation_for_open_window = animation;
+	}
+	// --animation-for-transient-window
+	if (config_lookup_string(&cfg, "animation-for-transient-window", &sval)) {
+		enum open_window_animation animation = parse_open_window_animation(sval);
+		if (animation >= OPEN_WINDOW_ANIMATION_INVALID) {
+			log_fatal("Invalid open-window animation %s", sval);
+			goto err;
+		}
+		opt->animation_for_transient_window = animation;
+	}
+	// --animation-for-unmap-window
+	if (config_lookup_string(&cfg, "animation-for-unmap-window", &sval)) {
+		enum open_window_animation animation = parse_open_window_animation(sval);
+		if (animation >= OPEN_WINDOW_ANIMATION_INVALID) {
+			log_fatal("Invalid unmap-window animation %s", sval);
+			goto err;
+		}
+		opt->animation_for_unmap_window = animation;
+	}
+	// --animation-for-next-tag
+	if (config_lookup_string(&cfg, "animation-for-next-tag", &sval)) {
+		enum open_window_animation animation = parse_open_window_animation(sval);
+		if (animation >= OPEN_WINDOW_ANIMATION_INVALID) {
+			log_fatal("Invalid next-tag animation %s", sval);
+			goto err;
+		}
+		opt->animation_for_next_tag = animation;
+	}
+	// --animation-for-prev-tag
+	if (config_lookup_string(&cfg, "animation-for-prev-tag", &sval)) {
+		enum open_window_animation animation = parse_open_window_animation(sval);
+		if (animation >= OPEN_WINDOW_ANIMATION_INVALID) {
+			log_fatal("Invalid prev-tag animation %s", sval);
+			goto err;
+		}
+		opt->animation_for_prev_tag = animation;
+	}
+	// --animations-exclude
+	parse_cfg_condlst(&cfg, &opt->animation_blacklist, "animation-exclude");
+
+	// --animation-stiffness
+	config_lookup_float(&cfg, "animation-stiffness-in-tag", &opt->animation_stiffness);
+	// --animation-stiffness-tag-change
+	config_lookup_float(&cfg, "animation-stiffness-tag-change", &opt->animation_stiffness_tag_change);
+	// --enable-fading-next-tag
+	lcfg_lookup_bool(&cfg, "enable-fading-next-tag", &opt->enable_fading_next_tag);
+	// --enable-fading-next-tag
+	lcfg_lookup_bool(&cfg, "enable-fading-prev-tag", &opt->enable_fading_prev_tag);
+	// --animation-window-mass
+	config_lookup_float(&cfg, "animation-window-mass", &opt->animation_window_mass);
+	// --animation-dampening
+	config_lookup_float(&cfg, "animation-dampening", &opt->animation_dampening);
+	// --animation-clamping
+	lcfg_lookup_bool(&cfg, "animation-clamping", &opt->animation_clamping);
 	// --focus-exclude
 	parse_cfg_condlst(&cfg, &opt->focus_blacklist, "focus-exclude");
 	// --invert-color-include

src/list.h

@@ -2,18 +2,7 @@
 #include <stdbool.h>
 #include <stddef.h>
 
-/**
- * container_of - cast a member of a structure out to the containing structure
- * @ptr:	the pointer to the member.
- * @type:	the type of the container struct this is embedded in.
- * @member:	the name of the member within the struct.
- *
- */
-#define container_of(ptr, type, member)                                                  \
-	({                                                                               \
-		const __typeof__(((type *)0)->member) *__mptr = (ptr);                   \
-		(type *)((char *)__mptr - offsetof(type, member));                       \
-	})
+#include "utils.h"
 
 struct list_node {
 	struct list_node *next, *prev;

src/options.c

@@ -184,6 +184,15 @@ static const struct picom_option picom_options[] = {
                                                                              "you want to attach a debugger to picom"},
     {"no-ewmh-fullscreen"          , no_argument      , 803, NULL          , "Do not use EWMH to detect fullscreen windows. Reverts to checking if a "
                                                                              "window is fullscreen based only on its size and coordinates."},
+    {"animations"                  ,no_argument       , 804, NULL          , "Enable/disable animations."},
+    {"animation-stiffness-in-tag"  , required_argument, 805, NULL          , "Animation speed in current tag (float)."},
+    {"animation-stiffness-tag-change", required_argument, 806, NULL        , "Animation speed when tag changes (change to a new desktop)."},
+    {"animation-dampening"         , required_argument, 807, NULL          , "Animation dampening ratio (spring dampening as an example)."},
+    {"animation-window-mass"       , required_argument, 808, NULL          , "Animation window mass (lower mass makes animations bumpy)."},
+    {"animation-clamping"          , no_argument      , 809, NULL          , "Enable/disable animation clamping. Disabling increases performance"},
+    {"animation-for-open-window"   , required_argument, 810, NULL          , "Set animation for opening window (Check sample.conf for options)."},
+    {"animation-for-transient-window", required_argument, 811, NULL        , "Set animation for transient (child) windows."},
+
 };
 // clang-format on
 
@@ -751,6 +760,52 @@ bool get_cfg(options_t *opt, int argc, char *const *argv, bool shadow_enable,
 			break;
 		P_CASEBOOL(802, debug_mode);
 		P_CASEBOOL(803, no_ewmh_fullscreen);
+		P_CASEBOOL(804, animations);
+		case 805:
+			// --animation-stiffness
+			opt->animation_stiffness = atof(optarg);
+			break;
+		case 806:
+			// --animation-stiffness-for-tags
+			opt->animation_stiffness_tag_change = atof(optarg);
+			break;
+		case 807:
+			// --animation-dampening
+			opt->animation_dampening = atof(optarg);
+			break;
+		case 808:
+			// --animation-window-masss
+			opt->animation_window_mass = atof(optarg);
+			break;
+		case 809:
+			// --animation-clamping
+			opt->animation_clamping = true;
+			break;
+		case 810: {
+			// --animation-for-open-window
+			enum open_window_animation animation = parse_open_window_animation(optarg);
+			if (animation >= OPEN_WINDOW_ANIMATION_INVALID) {
+				log_warn("Invalid open-window animation %s, ignoring.", optarg);
+			} else {
+				opt->animation_for_open_window = animation;
+			}
+			break;
+		}
+		case 811: {
+			// --animation-for-transient-window
+			enum open_window_animation animation = parse_open_window_animation(optarg);
+			if (animation >= OPEN_WINDOW_ANIMATION_INVALID) {
+				log_warn("Invalid transient-window animation %s, ignoring.", optarg);
+			} else {
+				opt->animation_for_transient_window = animation;
+			}
+			break;
+		}
+		case 812: {
+			// --animation-exclude
+			condlst_add(&opt->animation_blacklist, optarg);
+			break;
+		}
 		default: usage(argv[0], 1); break;
 #undef P_CASEBOOL
 		}

src/picom.c

@@ -888,85 +888,260 @@ static void handle_root_flags(session_t *ps) {
 	}
 }
 
+static struct managed_win *
+paint_preprocess(session_t *ps, bool *fade_running, bool *animation_running) {
 /**
  * Go through the window stack and calculate some parameters for rendering.
  *
  * @return whether the operation succeeded
  */
-static bool paint_preprocess(session_t *ps, bool *fade_running, bool *animation,
-                             struct managed_win **out_bottom) {
 	// XXX need better, more general name for `fade_running`. It really
-	// means if fade is still ongoing after the current frame is rendered
+	// means if fade is still ongoing after the current frame is rendered.
+	// Same goes for `animation_running`.
 	struct managed_win *bottom = NULL;
 	*fade_running = false;
-	*animation = false;
-	*out_bottom = NULL;
+	*animation_running = false;
+	auto now = get_time_ms();
 
 	// Fading step calculation
 	long long steps = 0L;
-	auto now = get_time_ms();
 	if (ps->fade_time) {
 		assert(now >= ps->fade_time);
 		steps = (now - ps->fade_time) / ps->o.fade_delta;
 	} else {
 		// Reset fade_time if unset
-		ps->fade_time = get_time_ms();
+		ps->fade_time = now;
 		steps = 0L;
 	}
 	ps->fade_time += steps * ps->o.fade_delta;
 
-	// First, let's process fading, and animated shaders
-	// TODO(yshui) check if a window is fully obscured, and if we don't need to
-	//             process fading or animation for it.
+	if (ps->o.animations && !ps->animation_time)
+		ps->animation_time = now;
+
+	double delta_secs = (double)(now - ps->animation_time) / 1000;
+
+	// First, let's process fading
 	win_stack_foreach_managed_safe(w, &ps->window_stack) {
 		const winmode_t mode_old = w->mode;
 		const bool was_painted = w->to_paint;
 		const double opacity_old = w->opacity;
 
+		// IMPORTANT: These window animation steps must happen before any other
+		// [pre]processing. This is because it changes the window's geometry.
+		if (ps->o.animations &&
+			!isnan(w->animation_progress) && w->animation_progress != 1.0 &&
+			ps->o.wintype_option[w->window_type].animation != 0 &&
+			win_is_mapped_in_x(w))
+		{
+			double neg_displacement_x =
+				w->animation_dest_center_x - w->animation_center_x;
+			double neg_displacement_y =
+				w->animation_dest_center_y - w->animation_center_y;
+			double neg_displacement_w = w->animation_dest_w - w->animation_w;
+			double neg_displacement_h = w->animation_dest_h - w->animation_h;
+			double animation_stiffness = ps->o.animation_stiffness;
+			if (!(w->animation_is_tag & ANIM_IN_TAG)) {
+				if (w->animation_is_tag & ANIM_SLOW)
+				    animation_stiffness = ps->o.animation_stiffness_tag_change;
+				else if (w->animation_is_tag & ANIM_FAST)
+				    animation_stiffness = ps->o.animation_stiffness_tag_change * 1.5;
+			}
+			if (w->state == WSTATE_FADING && !(w->animation_is_tag & ANIM_FADE))
+				w->opacity_target = win_calc_opacity_target(ps, w);
+			double acceleration_x =
+				(animation_stiffness * neg_displacement_x -
+					ps->o.animation_dampening * w->animation_velocity_x) /
+				ps->o.animation_window_mass;
+			double acceleration_y =
+				(animation_stiffness * neg_displacement_y -
+					ps->o.animation_dampening * w->animation_velocity_y) /
+				ps->o.animation_window_mass;
+			double acceleration_w =
+				(animation_stiffness * neg_displacement_w -
+					ps->o.animation_dampening * w->animation_velocity_w) /
+				ps->o.animation_window_mass;
+			double acceleration_h =
+				(animation_stiffness * neg_displacement_h -
+					ps->o.animation_dampening * w->animation_velocity_h) /
+				ps->o.animation_window_mass;
+			w->animation_velocity_x += acceleration_x * delta_secs;
+			w->animation_velocity_y += acceleration_y * delta_secs;
+			w->animation_velocity_w += acceleration_w * delta_secs;
+			w->animation_velocity_h += acceleration_h * delta_secs;
+
+			// Animate window geometry
+			double new_animation_x =
+				w->animation_center_x + w->animation_velocity_x * delta_secs;
+			double new_animation_y =
+				w->animation_center_y + w->animation_velocity_y * delta_secs;
+			double new_animation_w =
+				w->animation_w + w->animation_velocity_w * delta_secs;
+			double new_animation_h =
+				w->animation_h + w->animation_velocity_h * delta_secs;
+
+			// Negative new width/height causes segfault and it can happen
+			// when clamping disabled and shading a window
+			if (new_animation_h < 0)
+				new_animation_h = 0;
+
+			if (new_animation_w < 0)
+				new_animation_w = 0;
+
+			if (ps->o.animation_clamping) {
+				w->animation_center_x = clamp(
+					new_animation_x,
+					min2(w->animation_center_x, w->animation_dest_center_x),
+					max2(w->animation_center_x, w->animation_dest_center_x));
+				w->animation_center_y = clamp(
+					new_animation_y,
+					min2(w->animation_center_y, w->animation_dest_center_y),
+					max2(w->animation_center_y, w->animation_dest_center_y));
+				w->animation_w =
+					clamp(new_animation_w,
+							min2(w->animation_w, w->animation_dest_w),
+							max2(w->animation_w, w->animation_dest_w));
+				w->animation_h =
+					clamp(new_animation_h,
+							min2(w->animation_h, w->animation_dest_h),
+				 			max2(w->animation_h, w->animation_dest_h));
+			} else {
+				w->animation_center_x = new_animation_x;
+				w->animation_center_y = new_animation_y;
+				w->animation_w = new_animation_w;
+				w->animation_h = new_animation_h;
+			}
+
+			// Now we are done doing the math; we just need to submit our
+			// changes (if there are any).
+
+			struct win_geometry old_g = w->g;
+			double old_animation_progress = w->animation_progress;
+			new_animation_x = round(w->animation_center_x - w->animation_w * 0.5);
+			new_animation_y = round(w->animation_center_y - w->animation_h * 0.5);
+			new_animation_w = round(w->animation_w);
+			new_animation_h = round(w->animation_h);
+
+			bool position_changed =
+				new_animation_x != old_g.x || new_animation_y != old_g.y;
+			bool size_changed =
+				new_animation_w != old_g.width || new_animation_h != old_g.height;
+			bool geometry_changed = position_changed || size_changed;
+
+			// Mark past window region with damage
+			if (was_painted && geometry_changed)
+				add_damage_from_win(ps, w);
+
+			double x_dist = w->animation_dest_center_x - w->animation_center_x;
+			double y_dist = w->animation_dest_center_y - w->animation_center_y;
+			double w_dist = w->animation_dest_w - w->animation_w;
+			double h_dist = w->animation_dest_h - w->animation_h;
+			w->animation_progress =
+				1.0 - w->animation_inv_og_distance *
+					sqrt(x_dist * x_dist + y_dist * y_dist +
+							w_dist * w_dist + h_dist * h_dist);
+
+			// When clamping disabled we don't want the overlayed image to
+			// fade in again because process is moving to negative value
+			if (w->animation_progress < old_animation_progress)
+				w->animation_progress = old_animation_progress;
+
+			w->g.x = (int16_t)new_animation_x;
+			w->g.y = (int16_t)new_animation_y;
+			w->g.width = (uint16_t)new_animation_w;
+			w->g.height = (uint16_t)new_animation_h;
+
+
+			if (w->animation_is_tag > ANIM_IN_TAG && (((w->animation_is_tag & ANIM_FADE) && w->opacity_target == w->opacity)  || ((w->g.width == 0 || w->g.height == 0) && (w->animation_dest_w == 0 || w->animation_dest_h == 0)))) {
+					w->g.x = w->pending_g.x;
+					w->g.y = w->pending_g.y;
+					if (ps->o.animation_for_next_tag < OPEN_WINDOW_ANIMATION_ZOOM) {
+						w->g.width = w->pending_g.width;
+						w->g.height = w->pending_g.height;
+					} else {
+						w->g.width = 0;
+						w->g.height = 0;
+					}
+				}
+
+			// Submit window size change
+			if (size_changed) {
+				win_on_win_size_change(ps, w);
+
+				pixman_region32_clear(&w->bounding_shape);
+				pixman_region32_fini(&w->bounding_shape);
+				pixman_region32_init_rect(&w->bounding_shape, 0, 0,
+				                          (uint)w->widthb, (uint)w->heightb);
+
+				if (w->state != WSTATE_UNMAPPED && w->state != WSTATE_DESTROYING && w->state != WSTATE_UNMAPPING) {
+					win_clear_flags(w, WIN_FLAGS_PIXMAP_STALE);
+					win_process_image_flags(ps, w);
+				}
+			}
+			// Mark new window region with damage
+			if (was_painted && geometry_changed) {
+				add_damage_from_win(ps, w);
+				w->reg_ignore_valid = false;
+			}
+
+			// We can't check for 1 here as sometimes 1 = 0.999999999999999
+			// in case of floating numbers
+			if (w->animation_progress >= 0.999999999) {
+				w->animation_progress = 1;
+				w->animation_velocity_x = 0.0;
+				w->animation_velocity_y = 0.0;
+				w->animation_velocity_w = 0.0;
+				w->animation_velocity_h = 0.0;
+				w->opacity = win_calc_opacity_target(ps, w);
+			}
+			*animation_running = true;
+		}
+
 		if (win_should_dim(ps, w) != w->dim) {
 			w->dim = win_should_dim(ps, w);
 			add_damage_from_win(ps, w);
 		}
 
-		if (w->fg_shader && (w->fg_shader->attributes & SHADER_ATTRIBUTE_ANIMATED)) {
-			add_damage_from_win(ps, w);
-			*animation = true;
-		}
 
-		// Run fading
-		if (run_fade(ps, &w, steps)) {
-			*fade_running = true;
-		}
+		if (w->opacity != w->opacity_target) {
+			// Run fading
+			if (run_fade(ps, &w, steps)) {
+				*fade_running = true;
+			}
 
-		// Add window to damaged area if its opacity changes
-		// If was_painted == false, and to_paint is also false, we don't care
-		// If was_painted == false, but to_paint is true, damage will be added in
-		// the loop below
-		if (was_painted && w->opacity != opacity_old) {
-			add_damage_from_win(ps, w);
-		}
+			// Add window to damaged area if its opacity changes
+			// If was_painted == false, and to_paint is also false, we don't care
+			// If was_painted == false, but to_paint is true, damage will be added in
+			// the loop below
+			if (was_painted && w->opacity != opacity_old) {
+				add_damage_from_win(ps, w);
+			}
 
-		if (win_check_fade_finished(ps, w)) {
-			// the window has been destroyed because fading finished
-			continue;
-		}
 
-		if (win_has_frame(w)) {
-			w->frame_opacity = ps->o.frame_opacity;
-		} else {
-			w->frame_opacity = 1.0;
-		}
+			if (win_check_fade_finished(ps, w)) {
+				// the window has been destroyed because fading finished
+				continue;
+			}
 
-		// Update window mode
-		w->mode = win_calc_mode(w);
+			if (win_has_frame(w)) {
+				w->frame_opacity = ps->o.frame_opacity;
+			} else {
+				w->frame_opacity = 1.0;
+			}
 
-		// Destroy all reg_ignore above when frame opaque state changes on
-		// SOLID mode
-		if (was_painted && w->mode != mode_old) {
-			w->reg_ignore_valid = false;
+			// Update window mode
+			w->mode = win_calc_mode(w);
+
+			// Destroy all reg_ignore above when frame opaque state changes on
+			// SOLID mode
+			if (was_painted && w->mode != mode_old) {
+				w->reg_ignore_valid = false;
+			}
 		}
 	}
 
+	if (animation_running)
+		ps->animation_time = now;
+
 	// Opacity will not change, from now on.
 	rc_region_t *last_reg_ignore = rc_region_new();
 
@@ -1151,8 +1326,7 @@ static bool paint_preprocess(session_t *ps, bool *fade_running, bool *animation,
 		}
 	}
 
-	*out_bottom = bottom;
-	return true;
+	return bottom;
 }
 
 void root_damaged(session_t *ps) {
@@ -1346,7 +1520,7 @@ static int register_cm(session_t *ps) {
 			log_fatal("Failed to allocate memory");
 			return -1;
 		}
-		atom = get_atom(ps->atoms, buf);
+		atom = get_atom(ps->atoms, buf, ps->c.c);
 		free(buf);
 
 		xcb_get_selection_owner_reply_t *reply = xcb_get_selection_owner_reply(
@@ -1708,6 +1882,11 @@ static void fade_timer_callback(EV_P attr_unused, ev_timer *w, int revents attr_
 	queue_redraw(ps);
 }
 
+static void animation_timer_callback(EV_P attr_unused, ev_timer *w, int revents attr_unused) {
+	session_t *ps = session_ptr(w, animation_timer);
+	queue_redraw(ps);
+}
+
 static void handle_pending_updates(EV_P_ struct session *ps) {
 	if (ps->pending_updates) {
 		log_debug("Delayed handling of events, entering critical section");
@@ -1813,14 +1992,9 @@ static void draw_callback_impl(EV_P_ session_t *ps, int revents attr_unused) {
 	 * screen is not redirected. its sole purpose should be to decide whether the
 	 * screen should be redirected. */
 	bool fade_running = false;
-	bool animation = false;
+	bool animation_running = false;
 	bool was_redirected = ps->redirected;
-	struct managed_win *bottom = NULL;
-	if (!paint_preprocess(ps, &fade_running, &animation, &bottom)) {
-		log_fatal("Pre-render preparation has failed, exiting...");
-		exit(1);
-	}
-
+	auto bottom = paint_preprocess(ps, &fade_running, &animation_running);
 	ps->tmout_unredir_hit = false;
 
 	if (!was_redirected && ps->redirected) {
@@ -1842,6 +2016,13 @@ static void draw_callback_impl(EV_P_ session_t *ps, int revents attr_unused) {
 		ev_timer_set(&ps->fade_timer, fade_timeout(ps), 0);
 		ev_timer_start(EV_A_ & ps->fade_timer);
 	}
+	// Start/stop animation timer depends on whether windows are animating
+	if (!animation_running && ev_is_active(&ps->animation_timer)) {
+		ev_timer_stop(EV_A_ & ps->animation_timer);
+	} else if (animation_running && !ev_is_active(&ps->animation_timer)) {
+		ev_timer_set(&ps->animation_timer, 0, 0);
+		ev_timer_start(EV_A_ & ps->animation_timer);
+	}
 
 	int64_t after_preprocess_us;
 	clock_gettime(CLOCK_MONOTONIC, &now);
@@ -1882,23 +2063,15 @@ static void draw_callback_impl(EV_P_ session_t *ps, int revents attr_unused) {
 	if (!fade_running) {
 		ps->fade_time = 0L;
 	}
+	if (!animation_running) {
+		ps->animation_time = 0L;
+	}
 
 	ps->render_queued = false;
 
 	// TODO(yshui) Investigate how big the X critical section needs to be. There are
 	// suggestions that rendering should be in the critical section as well.
 
-	// Queue redraw if animation is running. This should be picked up by next present
-	// event.
-	if (animation) {
-		queue_redraw(ps);
-	}
-	if (ps->vblank_scheduler) {
-		// Even if we might not want to render during next vblank, we want to keep
-		// `backend_busy` up to date, so when the next render comes, we can
-		// immediately know if we can render.
-		vblank_scheduler_schedule(ps->vblank_scheduler, check_render_finish, ps);
-	}
 }
 
 static void draw_callback(EV_P_ ev_timer *w, int revents) {
@@ -2029,6 +2202,9 @@ static session_t *session_init(int argc, char **argv, Display *dpy,
 	    .redirected = false,
 	    .alpha_picts = NULL,
 	    .fade_time = 0L,
+	    .animation_time = 0L,
+	    .pending_reply_head = NULL,
+	    .pending_reply_tail = NULL,
 	    .quit = false,
 
 	    .expose_rects = NULL,
@@ -2277,8 +2453,9 @@ static session_t *session_init(int argc, char **argv, Display *dpy,
 	      c2_list_postprocess(ps, ps->o.window_shader_fg_rules) &&
 	      c2_list_postprocess(ps, ps->o.opacity_rules) &&
 	      c2_list_postprocess(ps, ps->o.rounded_corners_blacklist) &&
+	      c2_list_postprocess(ps, ps->o.focus_blacklist) &&
 	      c2_list_postprocess(ps, ps->o.corner_radius_rules) &&
-	      c2_list_postprocess(ps, ps->o.focus_blacklist))) {
+	      c2_list_postprocess(ps, ps->o.animation_blacklist))) {
 		log_error("Post-processing of conditionals failed, some of your rules "
 		          "might not work");
 	}
@@ -2474,7 +2651,7 @@ static session_t *session_init(int argc, char **argv, Display *dpy,
 
 	// Monitor screen changes if vsync_sw is enabled and we are using
 	// an auto-detected refresh rate, or when X RandR features are enabled
-	if (ps->randr_exists && ps->o.crop_shadow_to_monitor) {
+	if (ps->randr_exists) {
 		xcb_randr_select_input(ps->c.c, ps->c.screen_info->root,
 		                       XCB_RANDR_NOTIFY_MASK_SCREEN_CHANGE);
 		x_update_monitors(&ps->c, &ps->monitors);
@@ -2503,6 +2680,8 @@ static session_t *session_init(int argc, char **argv, Display *dpy,
 	ev_init(&ps->draw_timer, draw_callback);
 
 	ev_init(&ps->fade_timer, fade_timer_callback);
+	ev_init(&ps->animation_timer, animation_timer_callback);
+
 
 	// Set up SIGUSR1 signal handler to reset program
 	ev_signal_init(&ps->usr1_signal, reset_enable, SIGUSR1);
@@ -2808,6 +2987,7 @@ static void session_destroy(session_t *ps) {
 	// Stop libev event handlers
 	ev_timer_stop(ps->loop, &ps->unredir_timer);
 	ev_timer_stop(ps->loop, &ps->fade_timer);
+	ev_timer_stop(ps->loop, &ps->animation_timer);
 	ev_timer_stop(ps->loop, &ps->draw_timer);
 	ev_prepare_stop(ps->loop, &ps->event_check);
 	ev_signal_stop(ps->loop, &ps->usr1_signal);

src/utils.h

@@ -21,6 +21,7 @@
 #include "types.h"
 
 #define ARR_SIZE(arr) (sizeof(arr) / sizeof(arr[0]))
+#define CLEAR_MASK(x) x = 0;
 
 #ifdef __FAST_MATH__
 #warning Use of -ffast-math can cause rendering error or artifacts, \
@@ -58,11 +59,11 @@ safe_isnan(double a) {
 /// being always true or false.
 #define ASSERT_IN_RANGE(var, lower, upper)                                               \
 	do {                                                                             \
-		auto __tmp attr_unused = (var);                                          \
+		auto __assert_in_range_tmp attr_unused = (var);                          \
 		_Pragma("GCC diagnostic push");                                          \
 		_Pragma("GCC diagnostic ignored \"-Wtype-limits\"");                     \
-		assert(__tmp >= lower);                                                  \
-		assert(__tmp <= upper);                                                  \
+		assert(__assert_in_range_tmp >= lower);                                  \
+		assert(__assert_in_range_tmp <= upper);                                  \
 		_Pragma("GCC diagnostic pop");                                           \
 	} while (0)
 
@@ -112,11 +113,26 @@ safe_isnan(double a) {
 #define to_u32_checked(val)                                                              \
 	({                                                                               \
 		auto __to_tmp = (val);                                                   \
-		int64_t max attr_unused = UINT32_MAX; /* silence clang tautological      \
-		                                         comparison warning*/            \
-		ASSERT_IN_RANGE(__to_tmp, 0, max);                                       \
+		int64_t __to_u32_max attr_unused = UINT32_MAX; /* silence clang          \
+		                                                  tautological           \
+		                                                  comparison warning */  \
+		ASSERT_IN_RANGE(__to_tmp, 0, __to_u32_max);                              \
 		(uint32_t) __to_tmp;                                                     \
 	})
+
+/**
+ * container_of - cast a member of a structure out to the containing structure
+ * @ptr:	the pointer to the member.
+ * @type:	the type of the container struct this is embedded in.
+ * @member:	the name of the member within the struct.
+ *
+ */
+#define container_of(ptr, type, member)                                                  \
+	({                                                                               \
+		const __typeof__(((type *)0)->member) *__mptr = (ptr);                   \
+		(type *)((char *)__mptr - offsetof(type, member));                       \
+	})
+
 /**
  * Normalize an int value to a specific range.
  *
@@ -135,6 +151,19 @@ static inline int attr_const attr_unused normalize_i_range(int i, int min, int m
 	return i;
 }
 
+/**
+ * Linearly interpolate from a range into another.
+ *
+ * @param  a,b   first range
+ * @param  c,d   second range
+ * @param  value value to interpolate, should be in range [a,b]
+ * @return interpolated value in range [c,d]
+ */
+static inline int attr_const lerp_range(int a, int b, int c, int d, int value) {
+	ASSERT_IN_RANGE(value, a, b);
+	return (d-c)*(value-a)/(b-a) + c;
+}
+
 /// Generic integer abs()
 #define iabs(val)                                                                        \
 	({                                                                               \

src/win.c

@@ -307,6 +307,13 @@ static inline void win_release_pixmap(backend_t *base, struct managed_win *w) {
 		w->flags |= WIN_FLAGS_PIXMAP_NONE;
 	}
 }
+static inline void win_release_oldpixmap(backend_t *base, struct managed_win *w) {
+	log_debug("Releasing old_pixmap of window %#010x (%s)", w->base.id, w->name);
+	if (w->old_win_image) {
+		base->ops->release_image(base, w->old_win_image);
+		w->old_win_image = NULL;
+	}
+}
 static inline void win_release_shadow(backend_t *base, struct managed_win *w) {
 	log_debug("Releasing shadow of window %#010x (%s)", w->base.id, w->name);
 	assert(w->shadow_image);
@@ -403,6 +410,7 @@ void win_release_images(struct backend_base *backend, struct managed_win *w) {
 	if (!win_check_flags_all(w, WIN_FLAGS_PIXMAP_NONE)) {
 		assert(!win_check_flags_all(w, WIN_FLAGS_PIXMAP_STALE));
 		win_release_pixmap(backend, w);
+		win_release_oldpixmap(backend, w);
 	}
 
 	if (!win_check_flags_all(w, WIN_FLAGS_SHADOW_NONE)) {
@@ -476,6 +484,173 @@ static void win_update_properties(session_t *ps, struct managed_win *w) {
 	win_clear_all_properties_stale(w);
 }
 
+static void init_animation(session_t *ps, struct managed_win *w) {
+	CLEAR_MASK(w->animation_is_tag)
+	static int32_t randr_mon_center_x, randr_mon_center_y;
+	if (w->randr_monitor != -1) {
+		auto e = pixman_region32_extents(&ps->monitors.regions[w->randr_monitor]);
+		randr_mon_center_x = (e->x2 + e->x1) / 2, randr_mon_center_y = (e->y2 + e->y1) / 2;
+	} else {
+		randr_mon_center_x = ps->root_width / 2, randr_mon_center_y = ps->root_height / 2;
+	}
+	static double *anim_x, *anim_y, *anim_w, *anim_h;
+	enum open_window_animation animation;
+
+
+	animation = ps->o.animation_for_open_window;
+
+	if (w->window_type != WINTYPE_TOOLTIP &&
+		wid_has_prop(ps, w->client_win, ps->atoms->aWM_TRANSIENT_FOR)) {
+		animation = ps->o.animation_for_transient_window;
+	}
+
+	if (ps->o.wintype_option[w->window_type].animation != OPEN_WINDOW_ANIMATION_INVALID
+		&& !w->dwm_mask) {
+		animation = ps->o.wintype_option[w->window_type].animation;
+	}
+
+	anim_x = &w->animation_center_x, anim_y = &w->animation_center_y;
+	anim_w = &w->animation_w, anim_h = &w->animation_h;
+
+        if (w->dwm_mask & ANIM_PREV_TAG) {
+		animation = ps->o.animation_for_prev_tag;
+
+		if (ps->o.enable_fading_prev_tag) {
+		w->opacity_target_old = fmax(w->opacity_target, w->opacity_target_old);
+		w->state = WSTATE_FADING;
+		w->animation_is_tag |= ANIM_FADE;
+		}
+		if (ps->o.animation_for_prev_tag >= OPEN_WINDOW_ANIMATION_ZOOM) {
+		w->animation_is_tag |= ANIM_FAST;
+		w->dwm_mask |= ANIM_SPECIAL_MINIMIZE;
+		goto revert;
+		}
+		w->animation_is_tag |= ANIM_SLOW;
+        } else if (w->dwm_mask & ANIM_NEXT_TAG) {
+		animation = ps->o.animation_for_next_tag;
+		w->animation_is_tag |= animation >= OPEN_WINDOW_ANIMATION_ZOOM ? ANIM_FAST : ANIM_SLOW;
+		if (ps->o.enable_fading_next_tag) {
+		w->opacity = 0.0;
+		w->state = WSTATE_FADING;
+		}
+        } else if (w->dwm_mask & ANIM_UNMAP) {
+		animation = ps->o.animation_for_unmap_window;
+		revert:
+		anim_x = &w->animation_dest_center_x, anim_y = &w->animation_dest_center_y;
+		anim_w = &w->animation_dest_w, anim_h = &w->animation_dest_h;
+        }
+
+	double angle;
+	switch (animation) {
+	case OPEN_WINDOW_ANIMATION_NONE:  // No animation
+		w->animation_center_x = w->pending_g.x + w->pending_g.width * 0.5;
+		w->animation_center_y = w->pending_g.y + w->pending_g.height * 0.5;
+		w->animation_w = w->pending_g.width;
+		w->animation_h = w->pending_g.height;
+		break;
+	case OPEN_WINDOW_ANIMATION_FLYIN: // Fly-in from a random point outside the screen
+		// Compute random point off screen
+		angle = 2 * M_PI * ((double)rand() / RAND_MAX);
+		const double radius =
+		    sqrt(ps->root_width * ps->root_width + ps->root_height * ps->root_height);
+
+		// Set animation
+		*anim_x = randr_mon_center_x + radius * cos(angle);
+		*anim_y = randr_mon_center_y + radius * sin(angle);
+		*anim_w = 0;
+		*anim_h = 0;
+		break;
+	case OPEN_WINDOW_ANIMATION_SLIDE_UP: // Slide up the image, without changing its location
+		*anim_x = w->pending_g.x + w->pending_g.width * 0.5;
+		*anim_y = w->pending_g.y + w->pending_g.height;
+		*anim_w = w->pending_g.width;
+		*anim_h = 0;
+		break;
+	case OPEN_WINDOW_ANIMATION_SLIDE_DOWN:  // Slide down the image, without changing its location
+		*anim_x = w->pending_g.x + w->pending_g.width * 0.5;
+		*anim_y = w->pending_g.y;
+		*anim_w = w->pending_g.width;
+		*anim_h = 0;
+		break;
+	case OPEN_WINDOW_ANIMATION_SLIDE_LEFT:  // Slide left the image, without changing its location
+		*anim_x = w->pending_g.x + w->pending_g.width;
+		*anim_y = w->pending_g.y + w->pending_g.height * 0.5;
+		*anim_w = 0;
+		*anim_h = w->pending_g.height;
+		break;
+	case OPEN_WINDOW_ANIMATION_SLIDE_RIGHT: // Slide right the image, without changing its location
+		*anim_x = w->pending_g.x;
+		*anim_y = w->pending_g.y + w->pending_g.height * 0.5;
+		*anim_w = 0;
+		*anim_h = w->pending_g.height;
+		break;
+	case OPEN_WINDOW_ANIMATION_SLIDE_IN:
+		*anim_x = w->pending_g.x + w->pending_g.width * 0.5;
+		*anim_y = w->pending_g.y + w->pending_g.height * 0.5;
+		*anim_w = w->pending_g.width;
+		*anim_h = w->pending_g.height;
+		break;
+	case OPEN_WINDOW_ANIMATION_SLIDE_IN_CENTER:
+		*anim_x = randr_mon_center_x;
+		*anim_y = w->g.y + w->pending_g.height * 0.5;
+		*anim_w = w->pending_g.width;
+		*anim_h = w->pending_g.height;
+		break;
+	case OPEN_WINDOW_ANIMATION_SLIDE_OUT:
+		w->animation_dest_center_x = w->pending_g.x + w->pending_g.width * 0.5;
+		w->animation_dest_center_y = w->pending_g.y;
+		w->animation_dest_w = w->pending_g.width;
+		w->animation_dest_h = w->pending_g.height;
+		break;
+	case OPEN_WINDOW_ANIMATION_SLIDE_OUT_CENTER:
+		w->animation_dest_center_x = randr_mon_center_x;
+		w->animation_dest_center_y = w->pending_g.y;
+		w->animation_dest_w = w->pending_g.width;
+		w->animation_dest_h = w->pending_g.height;
+		break;
+	case OPEN_WINDOW_ANIMATION_ZOOM:  // Zoom-in the image, without changing its location
+		if (w->dwm_mask & ANIM_SPECIAL_MINIMIZE) {
+			*anim_x = w->g.x + w->g.width * 0.5;
+			*anim_y = w->g.y + w->g.height * 0.5;
+		} else {
+			*anim_x = w->pending_g.x + w->pending_g.width * 0.5;
+			*anim_y = w->pending_g.y + w->pending_g.height * 0.5;
+		}
+		*anim_w = 0;
+		*anim_h = 0;
+		break;
+	case OPEN_WINDOW_ANIMATION_MINIMIZE:
+		*anim_x = randr_mon_center_x;
+		*anim_y = randr_mon_center_y;
+		*anim_w = 0;
+		*anim_h = 0;
+		break;
+	case OPEN_WINDOW_ANIMATION_SQUEEZE:
+		if (w->dwm_mask & ANIM_PREV_TAG) {
+			*anim_h = 0;
+		} else {
+			*anim_x = w->pending_g.x + w->pending_g.width * 0.5;
+			*anim_y = w->pending_g.y + w->pending_g.height * 0.5;
+			*anim_w = w->pending_g.width;
+			*anim_h = 0;
+		}
+		break;
+	case OPEN_WINDOW_ANIMATION_SQUEEZE_BOTTOM:
+		if (w->dwm_mask & ANIM_PREV_TAG) {
+			*anim_y = w->g.y + w->g.height;
+			*anim_h = 0;
+		} else {
+			w->animation_center_x = w->pending_g.x + w->pending_g.width * 0.5;
+			w->animation_center_y = w->pending_g.y + w->pending_g.height;
+			w->animation_w = w->pending_g.width;
+			*anim_h = 0;
+			*anim_y = w->pending_g.y + w->pending_g.height;
+		}
+		break;
+	case OPEN_WINDOW_ANIMATION_INVALID: assert(false); break;
+	}
+}
+
 /// Handle non-image flags. This phase might set IMAGES_STALE flags
 void win_process_update_flags(session_t *ps, struct managed_win *w) {
 	// Whether the window was visible before we process the mapped flag. i.e.
@@ -517,8 +692,79 @@ void win_process_update_flags(session_t *ps, struct managed_win *w) {
 			add_damage_from_win(ps, w);
 		}
 
-		// Update window geometry
-		w->g = w->pending_g;
+
+
+        // Determine if a window should animate
+		if (win_should_animate(ps, w)) {
+			if (w->pending_g.y < 0 && w->g.y > 0 && abs(w->pending_g.y - w->g.y) >= w->pending_g.height)
+				w->dwm_mask = ANIM_PREV_TAG;
+			else if (w->pending_g.y > 0 && w->g.y < 0 && abs(w->pending_g.y - w->g.y) >= w->pending_g.height)
+				w->dwm_mask = ANIM_NEXT_TAG;
+
+			if (!was_visible || w->dwm_mask) {
+
+				// Set window-open animation
+				init_animation(ps, w);
+				if (!(w->dwm_mask & ANIM_SPECIAL_MINIMIZE)) {
+					w->animation_dest_center_x = w->pending_g.x + w->pending_g.width * 0.5;
+					w->animation_dest_center_y = w->pending_g.y + w->pending_g.height * 0.5;
+					w->animation_dest_w = w->pending_g.width;
+					w->animation_dest_h = w->pending_g.height;
+					w->g.x = (int16_t)round(w->animation_center_x -
+							    w->animation_w * 0.5);
+					w->g.y = (int16_t)round(w->animation_center_y -
+							    w->animation_h * 0.5);
+					w->g.width = (uint16_t)round(w->animation_w);
+					w->g.height = (uint16_t)round(w->animation_h);
+				}
+
+			} else {
+				w->animation_is_tag = ANIM_IN_TAG;
+				w->animation_dest_center_x =
+				    w->pending_g.x + w->pending_g.width * 0.5;
+				w->animation_dest_center_y =
+				    w->pending_g.y + w->pending_g.height * 0.5;
+				w->animation_dest_w = w->pending_g.width;
+				w->animation_dest_h = w->pending_g.height;
+			}
+
+			CLEAR_MASK(w->dwm_mask)
+			w->g.border_width = w->pending_g.border_width;
+			double x_dist = w->animation_dest_center_x - w->animation_center_x;
+			double y_dist = w->animation_dest_center_y - w->animation_center_y;
+			double w_dist = w->animation_dest_w - w->animation_w;
+			double h_dist = w->animation_dest_h - w->animation_h;
+			w->animation_inv_og_distance =
+				1.0 / sqrt(x_dist * x_dist + y_dist * y_dist +
+							w_dist * w_dist + h_dist * h_dist);
+
+			if (isinf(w->animation_inv_og_distance))
+				w->animation_inv_og_distance = 0;
+
+			// We only grab images if w->reg_ignore_valid is true as
+			// there's an ev_shape_notify() event fired quickly on new windows
+			// for e.g. in case of Firefox main menu and ev_shape_notify()
+			// sets the win_set_flags(w, WIN_FLAGS_SIZE_STALE); which
+			// brakes the new image captured and because this same event
+			// also sets w->reg_ignore_valid = false; too we check for it
+			if (w->reg_ignore_valid) {
+				if (w->old_win_image) {
+					ps->backend_data->ops->release_image(ps->backend_data,
+														w->old_win_image);
+					w->old_win_image = NULL;
+				}
+
+				// We only grab
+				if (w->win_image) {
+					w->old_win_image = ps->backend_data->ops->clone_image(
+						ps->backend_data, w->win_image, &w->bounding_shape);
+				}
+			}
+
+		w->animation_progress = 0.0;
+		} else {
+			w->g = w->pending_g;
+		}
 
 		// Whether a window is fullscreen changes based on its geometry
 		win_update_is_fullscreen(ps, w);
@@ -658,12 +904,14 @@ int win_update_name(session_t *ps, struct managed_win *w) {
 		return 0;
 	}
 
-	if (!(wid_get_text_prop(ps, w->client_win, ps->atoms->a_NET_WM_NAME, &strlst, &nstr))) {
+	if (!(wid_get_text_prop(&ps->c, ps->atoms, w->client_win,
+	                        ps->atoms->a_NET_WM_NAME, &strlst, &nstr))) {
 		log_debug("(%#010x): _NET_WM_NAME unset, falling back to "
 		          "WM_NAME.",
 		          w->client_win);
 
-		if (!wid_get_text_prop(ps, w->client_win, ps->atoms->aWM_NAME, &strlst, &nstr)) {
+		if (!wid_get_text_prop(&ps->c, ps->atoms, w->client_win,
+		                       ps->atoms->aWM_NAME, &strlst, &nstr)) {
 			log_debug("Unsetting window name for %#010x", w->client_win);
 			free(w->name);
 			w->name = NULL;
@@ -690,7 +938,8 @@ static int win_update_role(session_t *ps, struct managed_win *w) {
 	char **strlst = NULL;
 	int nstr = 0;
 
-	if (!wid_get_text_prop(ps, w->client_win, ps->atoms->aWM_WINDOW_ROLE, &strlst, &nstr)) {
+	if (!wid_get_text_prop(&ps->c, ps->atoms, w->client_win,
+	                       ps->atoms->aWM_WINDOW_ROLE, &strlst, &nstr)) {
 		return -1;
 	}
 
@@ -833,6 +1082,10 @@ double win_calc_opacity_target(session_t *ps, const struct managed_win *w) {
 	if (w->state == WSTATE_UNMAPPING || w->state == WSTATE_DESTROYING) {
 		return 0;
 	}
+    if ((w->state == WSTATE_FADING && (w->animation_is_tag & ANIM_FADE))) {
+        return 0;
+    }
+
 	// Try obeying opacity property and window type opacity firstly
 	if (w->has_opacity_prop) {
 		opacity = ((double)w->opacity_prop) / OPAQUE;
@@ -897,6 +1150,24 @@ bool win_should_fade(session_t *ps, const struct managed_win *w) {
 	return ps->o.wintype_option[w->window_type].fade;
 }
 
+/**
+ * Determine if a window should animate.
+ */
+bool win_should_animate(session_t *ps, const struct managed_win *w) {
+    if (!ps->o.animations) {
+        return false;
+    }
+    if (ps->o.wintype_option[w->window_type].animation == 0) {
+        log_debug("Animation disabled by window_type");
+        return false;
+    }
+    if (c2_match(ps, w, ps->o.animation_blacklist, NULL)) {
+        log_debug("Animation disabled by animation_exclude");
+        return false;
+    }
+    return true;
+}
+
 /**
  * Reread _COMPTON_SHADOW property from a window.
  *
@@ -1310,8 +1581,12 @@ void win_on_win_size_change(session_t *ps, struct managed_win *w) {
 	       w->state != WSTATE_UNMAPPING);
 
 	// Invalidate the shadow we built
-	win_set_flags(w, WIN_FLAGS_IMAGES_STALE);
-	win_release_mask(ps->backend_data, w);
+	// Do not set flags if window is unmapping and animation is running
+	if (w->state != WSTATE_UNMAPPED && w->state != WSTATE_DESTROYING &&
+	       w->state != WSTATE_UNMAPPING) {
+		win_set_flags(w, WIN_FLAGS_IMAGES_STALE);
+		win_release_mask(ps->backend_data, w);
+	}
 	ps->pending_updates = true;
 	free_paint(ps, &w->shadow_paint);
 }
@@ -1570,14 +1845,19 @@ struct win *fill_win(session_t *ps, struct win *w) {
 	    .blur_background = false,
 	    .reg_ignore = NULL,
 	    // The following ones are updated for other reasons
-	    .pixmap_damaged = false,          // updated by damage events
-	    .state = WSTATE_UNMAPPED,         // updated by window state changes
-	    .in_openclose = true,             // set to false after first map is done,
-	                                      // true here because window is just created
-	    .reg_ignore_valid = false,        // set to true when damaged
-	    .flags = WIN_FLAGS_IMAGES_NONE,        // updated by
-	                                           // property/attributes/etc
-	                                           // change
+	    .pixmap_damaged = false,         // updated by damage events
+	    .state = WSTATE_UNMAPPED,        // updated by window state changes
+	    .in_openclose = true,            // set to false after first map is done,
+	                                     // true here because window is just created
+	    .animation_velocity_x = 0.0,             // updated by window geometry changes
+	    .animation_velocity_y = 0.0,             // updated by window geometry changes
+	    .animation_velocity_w = 0.0,             // updated by window geometry changes
+	    .animation_velocity_h = 0.0,             // updated by window geometry changes
+	    .animation_progress = 1.0,               // updated by window geometry changes
+	    .animation_inv_og_distance = NAN,        // updated by window geometry changes
+	    .reg_ignore_valid = false,               // set to true when damaged
+	    .flags = WIN_FLAGS_IMAGES_NONE,          // updated by property/attributes/etc
+	                                             // change
 	    .stale_props = NULL,
 	    .stale_props_capacity = 0,
 
@@ -1603,6 +1883,7 @@ struct win *fill_win(session_t *ps, struct win *w) {
 	    // have no meaning or have no use until the window
 	    // is mapped
 	    .win_image = NULL,
+	    .old_win_image = NULL,
 	    .shadow_image = NULL,
 	    .mask_image = NULL,
 	    .prev_trans = NULL,
@@ -1876,7 +2157,8 @@ bool win_update_class(session_t *ps, struct managed_win *w) {
 	w->class_general = NULL;
 
 	// Retrieve the property string list
-	if (!wid_get_text_prop(ps, w->client_win, ps->atoms->aWM_CLASS, &strlst, &nstr)) {
+	if (!wid_get_text_prop(&ps->c, ps->atoms, w->client_win, ps->atoms->aWM_CLASS,
+	                       &strlst, &nstr)) {
 		return false;
 	}
 
@@ -2167,17 +2449,31 @@ static void unmap_win_finish(session_t *ps, struct managed_win *w) {
 		// Shadow image can be preserved.
 		if (!win_check_flags_all(w, WIN_FLAGS_PIXMAP_NONE)) {
 			win_release_pixmap(ps->backend_data, w);
+			win_release_oldpixmap(ps->backend_data, w);
 		}
 	} else {
 		assert(!w->win_image);
+		assert(!w->old_win_image);
 		assert(!w->shadow_image);
 	}
 
+	// Force animation to completed position
+	w->animation_velocity_x = 0;
+	w->animation_velocity_y = 0;
+	w->animation_velocity_w = 0;
+	w->animation_velocity_h = 0;
+	w->animation_progress = 1.0;
+
 	free_paint(ps, &w->paint);
 	free_paint(ps, &w->shadow_paint);
 
 	// Try again at binding images when the window is mapped next time
 	win_clear_flags(w, WIN_FLAGS_IMAGE_ERROR);
+
+	// Flag window so that it gets animated when it reapears
+	// in case it wasn't destroyed
+	win_set_flags(w, WIN_FLAGS_POSITION_STALE);
+	win_set_flags(w, WIN_FLAGS_SIZE_STALE);
 }
 
 /// Finish the destruction of a window (e.g. after fading has finished).
@@ -2453,6 +2749,30 @@ void unmap_win_start(session_t *ps, struct managed_win *w) {
 	w->opacity_target_old = fmax(w->opacity_target, w->opacity_target_old);
 	w->opacity_target = win_calc_opacity_target(ps, w);
 
+    if (ps->o.animations && ps->o.animation_for_unmap_window != OPEN_WINDOW_ANIMATION_NONE && ps->o.wintype_option[w->window_type].animation) {
+		w->dwm_mask = ANIM_UNMAP;
+		init_animation(ps, w);
+
+		double x_dist = w->animation_dest_center_x - w->animation_center_x;
+		double y_dist = w->animation_dest_center_y - w->animation_center_y;
+		double w_dist = w->animation_dest_w - w->animation_w;
+		double h_dist = w->animation_dest_h - w->animation_h;
+		w->animation_inv_og_distance =
+			1.0 / sqrt(x_dist * x_dist + y_dist * y_dist +
+						w_dist * w_dist + h_dist * h_dist);
+
+		if (isinf(w->animation_inv_og_distance))
+			w->animation_inv_og_distance = 0;
+
+		w->animation_progress = 0.0;
+
+		if (w->old_win_image) {
+			ps->backend_data->ops->release_image(ps->backend_data,
+												w->old_win_image);
+			w->old_win_image = NULL;
+		}
+    }
+
 #ifdef CONFIG_DBUS
 	// Send D-Bus signal
 	if (ps->o.dbus) {
@@ -2498,7 +2818,7 @@ bool win_check_fade_finished(session_t *ps, struct managed_win *w) {
 ///
 /// @return whether the window is destroyed and freed
 bool win_skip_fading(session_t *ps, struct managed_win *w) {
-	if (w->state == WSTATE_MAPPED || w->state == WSTATE_UNMAPPED) {
+	if ((w->state == WSTATE_MAPPED || w->state == WSTATE_UNMAPPED)) {
 		assert(w->opacity_target == w->opacity);
 		return false;
 	}
@@ -2510,11 +2830,12 @@ bool win_skip_fading(session_t *ps, struct managed_win *w) {
 // TODO(absolutelynothelix): rename to x_update_win_(randr_?)monitor and move to
 // the x.c.
 void win_update_monitor(struct x_monitors *monitors, struct managed_win *mw) {
-	mw->randr_monitor = -1;
 	for (int i = 0; i < monitors->count; i++) {
 		auto e = pixman_region32_extents(&monitors->regions[i]);
-		if (e->x1 <= mw->g.x && e->y1 <= mw->g.y &&
-		    e->x2 >= mw->g.x + mw->widthb && e->y2 >= mw->g.y + mw->heightb) {
+		if (((e->x1 <= mw->g.x || e->x1 <= mw->pending_g.x) &&
+		    (e->x2 >= mw->g.x + mw->widthb || e->x2 >= mw->pending_g.x + mw->widthb)) &&
+		    (e->y1 <= mw->g.y || e->y1 <= mw->pending_g.y) &&
+		    (e->y2 >= mw->g.y + mw->heightb || e->y2 >= mw->pending_g.y + mw->heightb)) {
 			mw->randr_monitor = i;
 			log_debug("Window %#010x (%s), %dx%d+%dx%d, is entirely on the "
 			          "monitor %d (%dx%d+%dx%d)",
@@ -2523,6 +2844,7 @@ void win_update_monitor(struct x_monitors *monitors, struct managed_win *mw) {
 			return;
 		}
 	}
+	mw->randr_monitor = -1;
 	log_debug("Window %#010x (%s), %dx%d+%dx%d, is not entirely on any monitor",
 	          mw->base.id, mw->name, mw->g.x, mw->g.y, mw->widthb, mw->heightb);
 }
@@ -2889,5 +3211,5 @@ win_stack_find_next_managed(const session_t *ps, const struct list_node *w) {
 /// Return whether this window is mapped on the X server side
 bool win_is_mapped_in_x(const struct managed_win *w) {
 	return w->state == WSTATE_MAPPING || w->state == WSTATE_FADING ||
-	       w->state == WSTATE_MAPPED || (w->flags & WIN_FLAGS_MAPPED);
+	       w->state == WSTATE_MAPPED || w->state == WSTATE_DESTROYING || (w->flags & WIN_FLAGS_MAPPED);
 }

src/win.h

@@ -96,11 +96,25 @@ struct win_geometry {
 	uint16_t border_width;
 };
 
+enum {
+    // dwm_mask
+    ANIM_PREV_TAG = 1,
+    ANIM_NEXT_TAG = (1 << 1),
+    ANIM_UNMAP = (1 << 2),
+    ANIM_SPECIAL_MINIMIZE = (1 << 3),
+    // animation_is_tag
+    ANIM_IN_TAG = 1,
+    ANIM_SLOW = (1 << 1),
+    ANIM_FAST = (1 << 2),
+    ANIM_FADE = (1 << 3),
+};
+
 struct managed_win {
 	struct win base;
 	/// backend data attached to this window. Only available when
 	/// `state` is not UNMAPPED
 	image_handle win_image;
+	image_handle old_win_image; // Old window image for interpolating window contents during animations
 	image_handle shadow_image;
 	image_handle mask_image;
 	/// Pointer to the next higher window to paint.
@@ -152,6 +166,8 @@ struct managed_win {
 	/// opacity state, window geometry, window mapped/unmapped state,
 	/// window mode of the windows above. DOES NOT INCLUDE the body of THIS WINDOW.
 	/// NULL means reg_ignore has not been calculated for this window.
+        /// 1 = tag prev  , 2 = tag next, 4 = unmap
+	uint32_t dwm_mask;
 	rc_region_t *reg_ignore;
 	/// Whether the reg_ignore of all windows beneath this window are valid
 	bool reg_ignore_valid;
@@ -169,6 +185,24 @@ struct managed_win {
 	bool unredir_if_possible_excluded;
 	/// Whether this window is in open/close state.
 	bool in_openclose;
+	/// Current position and destination, for animation
+	double animation_center_x,      animation_center_y;
+	double animation_dest_center_x, animation_dest_center_y;
+	double animation_w,      animation_h;
+	double animation_dest_w, animation_dest_h;
+	/// Spring animation velocity
+	double animation_velocity_x, animation_velocity_y;
+	double animation_velocity_w, animation_velocity_h;
+	/// Track animation progress; goes from 0 to 1
+	double animation_progress;
+	/// Inverse of the window distance at the start of animation, for
+	/// tracking animation progress
+	double animation_inv_og_distance;
+	/// Animation info if it is a tag change & check if its changing window sizes
+    	/// 0: no tag change
+    	/// 1: normal tag change animation
+    	/// 2: tag change animation that effects window size
+    	uint16_t animation_is_tag;
 
 	// Client window related members
 	/// ID of the top-level client window of the window.
@@ -462,6 +496,9 @@ bool win_check_flags_all(struct managed_win *w, uint64_t flags);
 /// Mark properties as stale for a window
 void win_set_properties_stale(struct managed_win *w, const xcb_atom_t *prop, int nprops);
 
+/// Determine if a window should animate
+bool attr_pure win_should_animate(session_t *ps, const struct managed_win *w);
+
 static inline attr_unused void win_set_property_stale(struct managed_win *w, xcb_atom_t prop) {
 	return win_set_properties_stale(w, (xcb_atom_t[]){prop}, 1);
 }

src/x.c

@@ -182,10 +182,9 @@ xcb_window_t wid_get_prop_window(struct x_connection *c, xcb_window_t wid, xcb_a
 /**
  * Get the value of a text property of a window.
  */
-bool wid_get_text_prop(session_t *ps, xcb_window_t wid, xcb_atom_t prop, char ***pstrlst,
-                       int *pnstr) {
-	assert(ps->server_grabbed);
-	auto prop_info = x_get_prop_info(&ps->c, wid, prop);
+bool wid_get_text_prop(struct x_connection *c, struct atom *atoms, xcb_window_t wid,
+                       xcb_atom_t prop, char ***pstrlst, int *pnstr) {
+	auto prop_info = x_get_prop_info(c, wid, prop);
 	auto type = prop_info.type;
 	auto format = prop_info.format;
 	auto length = prop_info.length;
@@ -194,8 +193,7 @@ bool wid_get_text_prop(session_t *ps, xcb_window_t wid, xcb_atom_t prop, char **
 		return false;
 	}
 
-	if (type != XCB_ATOM_STRING && type != ps->atoms->aUTF8_STRING &&
-	    type != ps->atoms->aC_STRING) {
+	if (type != XCB_ATOM_STRING && type != atoms->aUTF8_STRING && type != atoms->aC_STRING) {
 		log_warn("Text property %d of window %#010x has unsupported type: %d",
 		         prop, wid, type);
 		return false;
@@ -210,7 +208,7 @@ bool wid_get_text_prop(session_t *ps, xcb_window_t wid, xcb_atom_t prop, char **
 	xcb_generic_error_t *e = NULL;
 	auto word_count = (length + 4 - 1) / 4;
 	auto r = xcb_get_property_reply(
-	    ps->c.c, xcb_get_property(ps->c.c, 0, wid, prop, type, 0, word_count), &e);
+	    c->c, xcb_get_property(c->c, 0, wid, prop, type, 0, word_count), &e);
 	if (!r) {
 		log_debug_x_error(e, "Failed to get window property for %#010x", wid);
 		free(e);

src/x.h

@@ -261,8 +261,8 @@ xcb_window_t wid_get_prop_window(struct x_connection *c, xcb_window_t wid, xcb_a
  *                     array
  * @param[out] pnstr   Number of strings in the array
  */
-bool wid_get_text_prop(session_t *ps, xcb_window_t wid, xcb_atom_t prop, char ***pstrlst,
-                       int *pnstr);
+bool wid_get_text_prop(struct x_connection *c, struct atom *atoms, xcb_window_t wid,
+                       xcb_atom_t prop, char ***pstrlst, int *pnstr);
 
 const xcb_render_pictforminfo_t *
 x_get_pictform_for_visual(struct x_connection *, xcb_visualid_t);