Make QWidget::render() work correctly with all paint devices

Make sure QWidget::render takes correct code paths with all
kinds of paint devices.

Correctly restore the inRenderWithPainter flag. The old code
would not correctly restore the flag, likely leading to
inconsistencies. Remove the unused last parameter in
QWidgetPrivate::render. Remove the special handling
for QPrinter in the same method.

Task-number: QTBUG-26564
Change-Id: Iba43269b090abd8dd88c5225b75e1ee9239d58f9
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@digia.com>
Reviewed-by: Morten Johan Sørvig <morten.sorvig@digia.com>
Reviewed-by: Paul Olav Tvete <paul.tvete@digia.com>

2 files changed, 8 insertions, 23 deletions

diff --git a/src/widgets/kernel/qwidget.cpp b/src/widgets/kernel/qwidget.cpp
index 102e659fbf..c2f7a9b184 100644
--- a/src/widgets/kernel/qwidget.cpp
+++ b/src/widgets/kernel/qwidget.cpp
@@ -4677,7 +4677,8 @@ void QWidget::unsetCursor()
 void QWidget::render(QPaintDevice *target, const QPoint &targetOffset,
                      const QRegion &sourceRegion, RenderFlags renderFlags)
 {
-    d_func()->render(target, targetOffset, sourceRegion, renderFlags, false);
+    QPainter p(target);
+    render(&p, targetOffset, sourceRegion, renderFlags);
 }
 
 /*!
@@ -4721,9 +4722,6 @@ void QWidget::render(QPainter *painter, const QPoint &targetOffset,
         d->createExtra();
     d->extra->inRenderWithPainter = true;
 
-#ifdef Q_WS_MAC
-    d->render_helper(painter, targetOffset, toBePainted, renderFlags);
-#else
     QPaintEngine *engine = painter->paintEngine();
     Q_ASSERT(engine);
     QPaintEnginePrivate *enginePriv = engine->d_func();
@@ -4734,7 +4732,7 @@ void QWidget::render(QPainter *painter, const QPoint &targetOffset,
     // Render via a pixmap when dealing with non-opaque painters or printers.
     if (!inRenderWithPainter && (opacity < 1.0 || (target->devType() == QInternal::Printer))) {
         d->render_helper(painter, targetOffset, toBePainted, renderFlags);
-        d->extra->inRenderWithPainter = false;
+        d->extra->inRenderWithPainter = inRenderWithPainter;
         return;
     }
 
@@ -4755,7 +4753,7 @@ void QWidget::render(QPainter *painter, const QPoint &targetOffset,
         enginePriv->setSystemViewport(oldSystemClip);
     }
 
-    render(target, targetOffset, toBePainted, renderFlags);
+    d->render(target, targetOffset, toBePainted, renderFlags);
 
     // Restore system clip, viewport and transform.
     enginePriv->systemClip = oldSystemClip;
@@ -4764,9 +4762,8 @@ void QWidget::render(QPainter *painter, const QPoint &targetOffset,
 
     // Restore shared painter.
     d->setSharedPainter(oldPainter);
-#endif
 
-    d->extra->inRenderWithPainter = false;
+    d->extra->inRenderWithPainter = inRenderWithPainter;
 }
 
 static void sendResizeEvents(QWidget *target)
@@ -5204,8 +5201,7 @@ void QWidgetPrivate::drawWidget(QPaintDevice *pdev, const QRegion &rgn, const QP
 }
 
 void QWidgetPrivate::render(QPaintDevice *target, const QPoint &targetOffset,
-                            const QRegion &sourceRegion, QWidget::RenderFlags renderFlags,
-                            bool readyToRender)
+                            const QRegion &sourceRegion, QWidget::RenderFlags renderFlags)
 {
     if (!target) {
         qWarning("QWidget::render: null pointer to paint device");
@@ -5213,7 +5209,7 @@ void QWidgetPrivate::render(QPaintDevice *target, const QPoint &targetOffset,
     }
 
     const bool inRenderWithPainter = extra && extra->inRenderWithPainter;
-    QRegion paintRegion = !inRenderWithPainter && !readyToRender
+    QRegion paintRegion = !inRenderWithPainter
                           ? prepareToRender(sourceRegion, renderFlags)
                           : sourceRegion;
     if (paintRegion.isEmpty())
@@ -5272,23 +5268,12 @@ void QWidgetPrivate::render(QPaintDevice *target, const QPoint &targetOffset,
 
     flags |= DontSetCompositionMode;
 
-    if (target->devType() == QInternal::Printer) {
-        QPainter p(target);
-        render_helper(&p, targetOffset, paintRegion, renderFlags);
-        return;
-    }
-
-#ifndef Q_WS_MAC
     // Render via backingstore.
     drawWidget(target, paintRegion, offset, flags, sharedPainter());
 
     // Restore shared painter.
     if (oldSharedPainter)
         setSharedPainter(oldSharedPainter);
-#else
-    // Render via backingstore (no shared painter).
-    drawWidget(target, paintRegion, offset, flags, 0);
-#endif
 }
 
 void QWidgetPrivate::paintSiblingsRecursive(QPaintDevice *pdev, const QObjectList& siblings, int index, const QRegion &rgn,
diff --git a/src/widgets/kernel/qwidget_p.h b/src/widgets/kernel/qwidget_p.h
index bdfc57f7c3..41e36ee6a5 100644
--- a/src/widgets/kernel/qwidget_p.h
+++ b/src/widgets/kernel/qwidget_p.h
@@ -389,7 +389,7 @@ public:
     void render_helper(QPainter *painter, const QPoint &targetOffset, const QRegion &sourceRegion,
                        QWidget::RenderFlags renderFlags);
     void render(QPaintDevice *target, const QPoint &targetOffset, const QRegion &sourceRegion,
-                QWidget::RenderFlags renderFlags, bool readyToRender);
+                QWidget::RenderFlags renderFlags);
     void drawWidget(QPaintDevice *pdev, const QRegion &rgn, const QPoint &offset, int flags,
                     QPainter *sharedPainter = 0, QWidgetBackingStore *backingStore = 0);