Music player: Fix progress and thumb nail toolbar

A valid window handle must be set for this to work. Delay this
until QWidget::show() and add documentation.

Fixes: QTBUG-79348
Change-Id: Ib7db9568e0d70cb6194176f2da95a3b2087e403f
Reviewed-by: Leena Miettinen <riitta-leena.miettinen@qt.io>
Reviewed-by: Oliver Wolff <oliver.wolff@qt.io>

3 files changed, 26 insertions, 5 deletions

diff --git a/examples/winextras/musicplayer/doc/src/qtwinextras-musicplayer.qdoc b/examples/winextras/musicplayer/doc/src/qtwinextras-musicplayer.qdoc
index 8908699..8b8fd57 100644
--- a/examples/winextras/musicplayer/doc/src/qtwinextras-musicplayer.qdoc
+++ b/examples/winextras/musicplayer/doc/src/qtwinextras-musicplayer.qdoc
@@ -100,9 +100,19 @@
 
     \image qtwinextras-musicplayer-taskbar.png Screenshot of the Music Player taskbar
 
-    The following snippet shows how the taskbar button is prepared. The playback
-    progress is wired directly to the taskbar progress indicator by using signals
-    and slots.
+    The following snippets show how the taskbar button is prepared.
+
+    For the taskbar and the thumbnail toolbar to work, a native window handle
+    must be set by passing an instance of \c QWindow to
+    \c QWinTaskbarButton::setWindow() or \c QWinThumbnailToolBar::setWindow(),
+    respectively. This instance is created in the process of \c QWidget::show()
+    and can be retrieved by calling \c QWidget::windowHandle() afterwards.
+    We override \c QWidget::showEvent() for this purpose:
+
+    \snippet musicplayer/musicplayer.cpp 7
+
+    The playback progress is wired directly to the taskbar progress indicator
+    by using signals and slots.
 
     \snippet musicplayer/musicplayer.cpp 5
 
diff --git a/examples/winextras/musicplayer/musicplayer.cpp b/examples/winextras/musicplayer/musicplayer.cpp
index 12c6854..2ecff56 100644
--- a/examples/winextras/musicplayer/musicplayer.cpp
+++ b/examples/winextras/musicplayer/musicplayer.cpp
@@ -140,6 +140,18 @@ bool MusicPlayer::event(QEvent *event)
 }
 //! [0]
 
+//! [7]
+void MusicPlayer::showEvent(QShowEvent *event)
+{
+    QWidget::showEvent(event);
+    if (!taskbarButton->window()) {
+        auto window = windowHandle();
+        taskbarButton->setWindow(window);
+        thumbnailToolBar->setWindow(window);
+    }
+}
+//! [7]
+
 static bool canHandleDrop(const QDropEvent *event)
 {
     const QList<QUrl> urls = event->mimeData()->urls();
@@ -383,7 +395,6 @@ void MusicPlayer::createJumpList()
 void MusicPlayer::createTaskbar()
 {
     taskbarButton = new QWinTaskbarButton(this);
-    taskbarButton->setWindow(windowHandle());
 
     taskbarProgress = taskbarButton->progress();
     connect(positionSlider, &QAbstractSlider::valueChanged, taskbarProgress, &QWinTaskbarProgress::setValue);
@@ -397,7 +408,6 @@ void MusicPlayer::createTaskbar()
 void MusicPlayer::createThumbnailToolBar()
 {
     thumbnailToolBar = new QWinThumbnailToolBar(this);
-    thumbnailToolBar->setWindow(windowHandle());
 
     playToolButton = new QWinThumbnailToolButton(thumbnailToolBar);
     playToolButton->setEnabled(false);
diff --git a/examples/winextras/musicplayer/musicplayer.h b/examples/winextras/musicplayer/musicplayer.h
index 56f4c67..49dd25b 100644
--- a/examples/winextras/musicplayer/musicplayer.h
+++ b/examples/winextras/musicplayer/musicplayer.h
@@ -82,6 +82,7 @@ public slots:
 
 protected:
     bool event(QEvent *event) override;
+    void showEvent(QShowEvent *event) override;
     void dragEnterEvent(QDragEnterEvent *event) override;
     void dropEvent(QDropEvent *event) override;
     void mousePressEvent(QMouseEvent *event) override;