QPlatformWindow: change API for QPlatformWindow::setWindowState

The current implementation requests the platform window to set
the window state if it can, and return the actual window state
back.

The problem with this approach is that the platform window is created
as late as possible, so a call to QWindow::setWindowState would in
many (most?) cases never be forwarded to the platform window (instead,
the platform window is responsible to check the current window state
upon creation). As such, the window state might be left unsynched with
the platform window.

This patch suggests removing the return value from
QPlatformWindow::setWindowState. This will at least be consistent, so
that setting/getting state would produce the same result independent of
delayed window creation. If needed, we can later add new API to
QPlatformIntegration or QPlatformWindow for querying supported/actual
window state.

Change-Id: Ie43f56169656854a765ce88b47a808f8f3d51bb4
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@digia.com>
Reviewed-by: Thomas McGuire <thomas.mcguire@kdab.com>
Reviewed-by: Samuel Rødal <samuel.rodal@digia.com>
Reviewed-by: Morten Johan Sørvig <morten.sorvig@digia.com>

2 files changed, 3 insertions, 4 deletions

diff --git a/src/plugins/platforms/xcb/qxcbwindow.cpp b/src/plugins/platforms/xcb/qxcbwindow.cpp
index cefe1a7786..bab1884a9a 100644
--- a/src/plugins/platforms/xcb/qxcbwindow.cpp
+++ b/src/plugins/platforms/xcb/qxcbwindow.cpp
@@ -847,10 +847,10 @@ void QXcbWindow::changeNetWmState(bool set, xcb_atom_t one, xcb_atom_t two)
     Q_XCB_CALL(xcb_send_event(xcb_connection(), 0, m_screen->root(), XCB_EVENT_MASK_STRUCTURE_NOTIFY | XCB_EVENT_MASK_SUBSTRUCTURE_REDIRECT, (const char *)&event));
 }
 
-Qt::WindowState QXcbWindow::setWindowState(Qt::WindowState state)
+void QXcbWindow::setWindowState(Qt::WindowState state)
 {
     if (state == m_windowState)
-        return state;
+        return;
 
     // unset old state
     switch (m_windowState) {
@@ -905,7 +905,6 @@ Qt::WindowState QXcbWindow::setWindowState(Qt::WindowState state)
     connection()->sync();
 
     m_windowState = state;
-    return m_windowState;
 }
 
 void QXcbWindow::setNetWmWindowFlags(Qt::WindowFlags flags)
diff --git a/src/plugins/platforms/xcb/qxcbwindow.h b/src/plugins/platforms/xcb/qxcbwindow.h
index e2f62401dc..bd4d18a175 100644
--- a/src/plugins/platforms/xcb/qxcbwindow.h
+++ b/src/plugins/platforms/xcb/qxcbwindow.h
@@ -82,7 +82,7 @@ public:
 
     void setVisible(bool visible);
     void setWindowFlags(Qt::WindowFlags flags);
-    Qt::WindowState setWindowState(Qt::WindowState state);
+    void setWindowState(Qt::WindowState state);
     WId winId() const;
     void setParent(const QPlatformWindow *window);