Code refactor

More flexible tool API
Minor code format fixes
Clipboard freeze fixed(?)
Arrow correcly growing close to the start point
Improve maintainability
Add undo/redo stack

src/widgets/capture/modificationcommand.cpp

@@ -0,0 +1,38 @@
+// 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 "modificationcommand.h"
+#include <QPainter>
+
+ModificationCommand::ModificationCommand(QPixmap *p, CaptureTool *t) :
+    m_pixmap(p), m_tool(t)
+{
+}
+
+void ModificationCommand::undo() {
+    m_tool->undo(*m_pixmap);
+}
+
+QString ModificationCommand::text() const {
+    return m_tool->name();
+}
+
+void ModificationCommand::redo() {
+    QPainter p(m_pixmap);
+    p.setRenderHint(QPainter::Antialiasing);
+    m_tool->process(p, *m_pixmap, true);
+}