Selection refactor

New improved selection code:
- Selection decopuled into a new class
- When you drag the selection against the limits it won't become
permanently smaller, it will "bounce" trying to recover its size.
If you drop it again it will adapt its size to the borders of the
screen.
- Fixed bugs in the button position algorithm.
- Implemented selection animations for future implementations.

src/widgets/capture/selectionwidget.cpp

@@ -0,0 +1,128 @@
+// Copyright(c) 2017-2018 Alejandro Sirgo Rica & Contributors
+//
+// This file is part of Flameshot.
+//
+//     Flameshot is free software: you can redistribute it and/or modify
+//     it under the terms of the GNU General Public License as published by
+//     the Free Software Foundation, either version 3 of the License, or
+//     (at your option) any later version.
+//
+//     Flameshot is distributed in the hope that it will be useful,
+//     but WITHOUT ANY WARRANTY; without even the implied warranty of
+//     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+//     GNU General Public License for more details.
+//
+//     You should have received a copy of the GNU General Public License
+//     along with Flameshot.  If not, see <http://www.gnu.org/licenses/>.
+
+#include "selectionwidget.h"
+#include "src/utils/globalvalues.h"
+#include <QPainter>
+#include <QPropertyAnimation>
+
+SelectionWidget::SelectionWidget(const QColor &c, QWidget *parent) :
+    QWidget(parent), m_color(c)
+{
+    m_animation = new QPropertyAnimation(this, "geometry", this);
+    m_animation->setEasingCurve(QEasingCurve::InOutQuad);
+    m_animation->setDuration(200);
+    connect(m_animation, &QPropertyAnimation::finished,
+            this, &SelectionWidget::animationEnded);
+
+    setAttribute(Qt::WA_TransparentForMouseEvents);
+    int sideVal = GlobalValues::buttonBaseSize() * 0.6;
+    int handleSide = sideVal / 2;
+    const QRect areaRect(0, 0, sideVal, sideVal);
+    const QRect handleRect(0, 0, handleSide, handleSide);
+    m_TLHandle = m_TRHandle = m_BLHandle = m_BRHandle =
+            m_LHandle = m_THandle = m_RHandle = m_BHandle= handleRect;
+    m_TLArea = m_TRArea = m_BLArea = m_BRArea = areaRect;
+
+    m_areaOffset = QPoint(-sideVal/2, -sideVal/2);
+    m_handleOffset = QPoint(-handleSide/2, -handleSide/2);
+}
+
+SelectionWidget::SideType SelectionWidget::getMouseSide(const QPoint &point) const {
+    if (m_TLArea.contains(point)) {
+        return TOPLEFT_SIDE;
+    } else if (m_TRArea.contains(point)) {
+        return TOPRIGHT_SIDE;
+    } else if (m_BLArea.contains(point)) {
+        return BOTTONLEFT_SIDE;
+    } else if (m_BRArea.contains(point)) {
+        return BOTTONRIGHT_SIDE;
+    } else if (m_LArea.contains(point)) {
+        return LEFT_SIDE;
+    } else if (m_TArea.contains(point)) {
+        return TOP_SIDE;
+    } else if (m_RArea.contains(point)) {
+        return RIGHT_SIDE;
+    } else if (m_BArea.contains(point)) {
+        return  BOTTON_SIDE;
+    } else {
+        return NO_SIDE;
+    }
+}
+
+QVector<QRect> SelectionWidget::handlerAreas() {
+    QVector<QRect> areas;
+    areas << m_TLHandle << m_TRHandle << m_BLHandle << m_BRHandle
+      <<m_LHandle << m_THandle << m_RHandle << m_BHandle;
+    return areas;
+}
+
+void SelectionWidget::setGeometryAnimated(const QRect &r) {
+    if (isVisible()) {
+        m_animation->setStartValue(geometry());
+        m_animation->setEndValue(r);
+        m_animation->start();
+    }
+}
+
+void SelectionWidget::saveGeometry() {
+    m_geometryBackup = geometry();
+}
+
+QRect SelectionWidget::savedGeometry() {
+    return m_geometryBackup;
+}
+
+void SelectionWidget::paintEvent(QPaintEvent *) {
+    QPainter p(this);
+    p.setPen(m_color);
+    p.drawRect(rect() + QMargins(0, 0, -1, -1));
+}
+
+void SelectionWidget::resizeEvent(QResizeEvent *) {
+    updateAreas();
+}
+
+void SelectionWidget::moveEvent(QMoveEvent *) {
+    updateAreas();
+}
+
+void SelectionWidget::updateColor(const QColor &c) {
+    m_color = c;
+}
+
+void SelectionWidget::updateAreas() {
+    QRect r = rect();
+    m_TLArea.moveTo(m_areaOffset + pos());
+    m_TRArea.moveTo(r.topRight() + m_areaOffset + pos());
+    m_BLArea.moveTo(r.bottomLeft() + m_areaOffset + pos());
+    m_BRArea.moveTo(r.bottomRight() + m_areaOffset + pos());
+
+    m_LArea = QRect(m_TLArea.bottomLeft(), m_BLArea.topRight());
+    m_TArea = QRect(m_TLArea.topRight(), m_TRArea.bottomLeft());
+    m_RArea = QRect(m_TRArea.bottomLeft(), m_BRArea.topRight());
+    m_BArea = QRect(m_BLArea.topRight(), m_BRArea.bottomLeft());
+
+    m_TLHandle.moveTo(m_TLArea.center() + m_handleOffset);
+    m_BLHandle.moveTo(m_BLArea.center() + m_handleOffset);
+    m_TRHandle.moveTo(m_TRArea.center() + m_handleOffset);
+    m_BRHandle.moveTo(m_BRArea.center() + m_handleOffset);
+    m_LHandle.moveTo(m_LArea.center() + m_handleOffset);
+    m_THandle.moveTo(m_TArea.center() + m_handleOffset);
+    m_RHandle.moveTo(m_RArea.center() + m_handleOffset);
+    m_BHandle.moveTo(m_BArea.center() + m_handleOffset);
+}