Support transparency in qt5 system tray icons, regardless of tray visual

This ports the Qt4 method of supporting the system tray
window visual that has an alpha channel as well as ones
that do not. We detect whether or not we have a 32-bit
format and either use a Qt::transparent background, or
call xcb_clear_region before painting the icon.

[ChangeLog][Linux/XCB] Fix transparency of tray icons in cases where
there is no alpha channel or system tray visual.

Task-number: QTBUG-35832
Change-Id: I43d500c39846d2916dd39f8c47c8d85e59b49cae
Reviewed-by: Uli Schlachter <psychon@znc.in>
Reviewed-by: Allan Sandfeld Jensen <allan.jensen@digia.com>

1 files changed, 7 insertions, 0 deletions

diff --git a/src/plugins/platforms/xcb/qxcbnativeinterface.h b/src/plugins/platforms/xcb/qxcbnativeinterface.h
index f860e0d267..ff5f358298 100644
--- a/src/plugins/platforms/xcb/qxcbnativeinterface.h
+++ b/src/plugins/platforms/xcb/qxcbnativeinterface.h
@@ -107,6 +107,8 @@ public:
 
     Q_INVOKABLE void beep();
     Q_INVOKABLE bool systemTrayAvailable(const QScreen *screen) const;
+    Q_INVOKABLE void clearRegion(const QWindow *qwindow, const QRect& rect);
+    Q_INVOKABLE bool systrayVisualHasAlphaChannel();
     Q_INVOKABLE bool requestSystemTrayWindowDock(const QWindow *window);
     Q_INVOKABLE QRect systemTrayWindowGlobalGeometry(const QWindow *window);
 
@@ -114,8 +116,13 @@ signals:
     void systemTrayWindowChanged(QScreen *screen);
 
 private:
+    xcb_window_t locateSystemTray(xcb_connection_t *conn, const QXcbScreen *screen);
+
     const QByteArray m_genericEventFilterType;
 
+    xcb_atom_t m_sysTraySelectionAtom;
+    xcb_visualid_t m_systrayVisualId;
+
     static QXcbScreen *qPlatformScreenForWindow(QWindow *window);
 };