Make the heart throb

src/calibre/gui2/main.ui

@@ -96,10 +96,7 @@
        </widget>
       </item>
       <item>
-       <widget class="QToolButton" name="donate_button">
-        <property name="cursor">
-         <cursorShape>PointingHandCursor</cursorShape>
-        </property>
+       <widget class="ThrobbingButton" name="donate_button">
         <property name="text">
          <string>...</string>
         </property>
@@ -107,12 +104,6 @@
          <iconset resource="../../../resources/images.qrc">
           <normaloff>:/images/donate.svg</normaloff>:/images/donate.svg</iconset>
         </property>
-        <property name="iconSize">
-         <size>
-          <width>64</width>
-          <height>64</height>
-         </size>
-        </property>
         <property name="autoRaise">
          <bool>true</bool>
         </property>
@@ -552,6 +543,11 @@
    <extends>QComboBox</extends>
    <header>calibre.gui2.search_box</header>
   </customwidget>
+  <customwidget>
+   <class>ThrobbingButton</class>
+   <extends>QToolButton</extends>
+   <header>calibre/gui2/throbber.h</header>
+  </customwidget>
  </customwidgets>
  <resources>
   <include location="../../../resources/images.qrc"/>

src/calibre/gui2/throbber.py

@@ -0,0 +1,70 @@
+#!/usr/bin/env python
+# vim:fileencoding=UTF-8:ts=4:sw=4:sta:et:sts=4:ai
+
+__license__   = 'GPL v3'
+__copyright__ = '2010, Kovid Goyal <kovid@kovidgoyal.net>'
+__docformat__ = 'restructuredtext en'
+
+
+from PyQt4.Qt import QToolButton, QSize, QPropertyAnimation, Qt, \
+        QMetaObject
+
+from calibre.gui2 import config
+
+class ThrobbingButton(QToolButton):
+
+    def __init__(self, *args):
+        QToolButton.__init__(self, *args)
+        self.animation = QPropertyAnimation(self, 'iconSize', self)
+        self.animation.setDuration(60/72.*1000)
+        self.animation.setLoopCount(4)
+        self.normal_icon_size = QSize(64, 64)
+        self.animation.valueChanged.connect(self.value_changed)
+        self.setCursor(Qt.PointingHandCursor)
+        self.animation.finished.connect(self.animation_finished)
+
+    def set_normal_icon_size(self, w, h):
+        self.normal_icon_size = QSize(w, h)
+        self.setIconSize(self.normal_icon_size)
+        self.setMinimumSize(self.sizeHint())
+
+    def animation_finished(self):
+        self.setIconSize(self.normal_icon_size)
+
+    def enterEvent(self, ev):
+        self.start_animation()
+
+    def leaveEvent(self, ev):
+        self.stop_animation()
+
+    def value_changed(self, val):
+        self.update()
+
+    def start_animation(self):
+        if config['disable_animations']: return
+        if self.animation.state() != self.animation.Stopped or not self.isVisible():
+            return
+        size = self.normal_icon_size.width()
+        smaller = int(0.7 * size)
+        self.animation.setStartValue(QSize(smaller, smaller))
+        self.animation.setEndValue(self.normal_icon_size)
+        QMetaObject.invokeMethod(self.animation, 'start', Qt.QueuedConnection)
+
+    def stop_animation(self):
+        self.animation.stop()
+        self.animation_finished()
+
+
+if __name__ == '__main__':
+    from PyQt4.Qt import QApplication, QWidget, QHBoxLayout, QIcon
+    app = QApplication([])
+    w = QWidget()
+    w.setLayout(QHBoxLayout())
+    b = ThrobbingButton()
+    b.setIcon(QIcon(I('donate.svg')))
+    w.layout().addWidget(b)
+    w.show()
+    b.set_normal_icon_size(64, 64)
+    b.start_animation()
+
+    app.exec_()

src/calibre/gui2/ui.py

@@ -281,6 +281,8 @@ class Main(MainWindow, Ui_MainWindow, DeviceMixin, ToolbarMixin, # {{{
 
         self.read_settings()
         self.finalize_layout()
+        self.donate_button.set_normal_icon_size(64, 64)
+        self.donate_button.start_animation()
 
     def resizeEvent(self, ev):
         MainWindow.resizeEvent(self, ev)