The original commit message follows.
Fixes: Fix the windows PaintOnScreen issue once and for all
Details: To allow both the case where X11 people accidentally set
PaintOnScreen (which should not have any effect on windows)
and where people set it and subclass with paintEngine() {
return 0 } to use GDI / DirectX we do this rather nasty hack.
Original commit in Qt4:
07a2f68bd5869152471e4ffc4a63c683ef141ae8
Autotest: tst_QWidget::paintOnScreenPossible
Change-Id: Ifbb7dc4611959be3ecc362c29a1c3436b0e0fa82
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@nokia.com>
Reviewed-by: Gunnar Sletta <gunnar.sletta@nokia.com>
#ifndef QT_NO_IM
, inheritsInputMethodHints(0)
#endif
+#if defined(Q_OS_WIN)
+ , noPaintOnScreen(0)
+#endif
#if defined(Q_WS_X11)
, picture(0)
#elif defined(Q_WS_WIN)
- , noPaintOnScreen(0)
#ifndef QT_NO_GESTURES
, nativeGesturePanEnabled(0)
#endif
Q_ASSERT_X(sizeof(d->high_attributes)*8 >= (Qt::WA_AttributeCount - sizeof(uint)*8),
"QWidget::setAttribute(WidgetAttribute, bool)",
"QWidgetPrivate::high_attributes[] too small to contain all attributes in WidgetAttribute");
-#ifdef Q_WS_WIN
- // ### Don't use PaintOnScreen+paintEngine() to do native painting in 5.0
+#ifdef Q_OS_WIN
+ // ### Don't use PaintOnScreen+paintEngine() to do native painting in some future release
if (attribute == Qt::WA_PaintOnScreen && on && !inherits("QGLWidget")) {
- // see qwidget_win.cpp, ::paintEngine for details
+ // see qwidget_qpa.cpp, ::paintEngine for details
paintEngine();
if (d->noPaintOnScreen)
return;
#endif
// *************************** Platform specific ************************************
+#if defined(Q_OS_WIN)
+ uint noPaintOnScreen : 1; // see qwidget_qpa.cpp ::paintEngine()
+#endif
#if defined(Q_WS_X11) // <----------------------------------------------------------- X11
Qt::HANDLE picture;
static QWidget *mouseGrabber;
QPoint mapToGlobal(const QPoint &pos) const;
QPoint mapFromGlobal(const QPoint &pos) const;
#elif defined(Q_WS_WIN) // <--------------------------------------------------------- WIN
- uint noPaintOnScreen : 1; // see qwidget_win.cpp ::paintEngine()
#ifndef QT_NO_GESTURES
uint nativeGesturePanEnabled : 1;
#endif
QPaintEngine *QWidget::paintEngine() const
{
qWarning("QWidget::paintEngine: Should no longer be called");
+
+#ifdef Q_OS_WIN
+ // We set this bit which is checked in setAttribute for
+ // Qt::WA_PaintOnScreen. We do this to allow these two scenarios:
+ //
+ // 1. Users accidentally set Qt::WA_PaintOnScreen on X and port to
+ // Windows which would mean suddenly their widgets stop working.
+ //
+ // 2. Users set paint on screen and subclass paintEngine() to
+ // return 0, in which case we have a "hole" in the backingstore
+ // allowing use of GDI or DirectX directly.
+ //
+ // 1 is WRONG, but to minimize silent failures, we have set this
+ // bit to ignore the setAttribute call. 2. needs to be
+ // supported because its our only means of embedding native
+ // graphics stuff.
+ const_cast<QWidgetPrivate *>(d_func())->noPaintOnScreen = 1;
+#endif
+
return 0; //##### @@@
}