From d9c34e9cdd24937a3c487d0f525a8b8b38ee1ad5 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Morten=20Johan=20S=C3=B8rvig?= <morten.sorvig@digia.com>
Date: Mon, 26 Aug 2013 10:49:48 +0200
Subject: [PATCH] Repaint widgets on screen change.
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Add a screenChanged handler slot to QWidgetWindow,
which calls markDirty() on the backing store with
the BufferInvalid and UpdateNow flags set.

Update CocoaBackingStore to create a new buffer on
window devicePixelRatio change. Use the
QCocoaWindow::devicePixelRatio() implementation instead
of a duplicate implementation in the backing store.

The plan is to replace this implementation with one
based on QUpdateWindowRequestEvent for Qt 5.4

Change-Id: I8e521c53df4ac90815613e730fe821996334721f
Reviewed-by: Jørgen Lind <jorgen.lind@digia.com>
---
 .../platforms/cocoa/qcocoabackingstore.mm     | 23 ++++++++-----------
 src/widgets/kernel/qwidgetwindow.cpp          | 14 +++++++++++
 src/widgets/kernel/qwidgetwindow_qpa_p.h      |  1 +
 3 files changed, 24 insertions(+), 14 deletions(-)

diff --git a/src/plugins/platforms/cocoa/qcocoabackingstore.mm b/src/plugins/platforms/cocoa/qcocoabackingstore.mm
index 3ca611b537..2222b51a42 100644
--- a/src/plugins/platforms/cocoa/qcocoabackingstore.mm
+++ b/src/plugins/platforms/cocoa/qcocoabackingstore.mm
@@ -59,25 +59,20 @@ QCocoaBackingStore::~QCocoaBackingStore()
 
 QPaintDevice *QCocoaBackingStore::paintDevice()
 {
-    if (m_qImage.size() / m_qImage.devicePixelRatio() != m_requestedSize) {
+    QCocoaWindow *cocoaWindow = static_cast<QCocoaWindow *>(window()->handle());
+    int windowDevicePixelRatio = int(cocoaWindow->devicePixelRatio());
+
+    // Receate the backing store buffer if the effective buffer size has changed,
+    // either due to a window resize or devicePixelRatio change.
+    QSize effectiveBufferSize = m_requestedSize * windowDevicePixelRatio;
+    if (m_qImage.size() != effectiveBufferSize) {
         CGImageRelease(m_cgImage);
         m_cgImage = 0;
 
-        int scaleFactor = 1;
-#if MAC_OS_X_VERSION_MAX_ALLOWED >= MAC_OS_X_VERSION_10_7
-        if (QSysInfo::MacintoshVersion >= QSysInfo::MV_10_7) {
-            QCocoaWindow *cocoaWindow = static_cast<QCocoaWindow *>(window()->handle());
-            if (cocoaWindow && cocoaWindow->m_contentView && [cocoaWindow->m_contentView window]) {
-                scaleFactor = int([[cocoaWindow->m_contentView window] backingScaleFactor]);
-            }
-        }
-#endif
-
-        QCocoaWindow *cocoaWindow = static_cast<QCocoaWindow *>(window()->handle());
         QImage::Format format = (window()->format().hasAlpha() || cocoaWindow->m_drawContentBorderGradient)
                 ? QImage::Format_ARGB32_Premultiplied : QImage::Format_RGB32;
-        m_qImage = QImage(m_requestedSize * scaleFactor, format);
-        m_qImage.setDevicePixelRatio(scaleFactor);
+        m_qImage = QImage(effectiveBufferSize, format);
+        m_qImage.setDevicePixelRatio(windowDevicePixelRatio);
         if (format == QImage::Format_ARGB32_Premultiplied)
             m_qImage.fill(Qt::transparent);
     }
diff --git a/src/widgets/kernel/qwidgetwindow.cpp b/src/widgets/kernel/qwidgetwindow.cpp
index e50736d6b8..ef138267bb 100644
--- a/src/widgets/kernel/qwidgetwindow.cpp
+++ b/src/widgets/kernel/qwidgetwindow.cpp
@@ -100,6 +100,7 @@ QWidgetWindow::QWidgetWindow(QWidget *widget)
         setSurfaceType(QSurface::RasterGLSurface);
     }
     connect(m_widget, &QObject::objectNameChanged, this, &QWidgetWindow::updateObjectName);
+    connect(this, SIGNAL(screenChanged(QScreen*)), this, SLOT(repaintWindow()));
 }
 
 QWidgetWindow::~QWidgetWindow()
@@ -560,6 +561,19 @@ void QWidgetWindow::updateGeometry()
     m_widget->data->fstrut_dirty = false;
 }
 
+// Invalidates the backing store buffer and repaints immediately.
+// ### Qt 5.4: replace with QUpdateWindowRequestEvent.
+void QWidgetWindow::repaintWindow()
+{
+    if (!m_widget->isVisible() || !m_widget->updatesEnabled())
+        return;
+
+    QTLWExtra *tlwExtra = m_widget->window()->d_func()->maybeTopData();
+    if (tlwExtra && !tlwExtra->inTopLevelResize && tlwExtra->backingStore)
+        tlwExtra->backingStoreTracker->markDirty(m_widget->rect(), m_widget,
+                                                 QWidgetBackingStore::UpdateNow, QWidgetBackingStore::BufferInvalid);
+}
+
 Qt::WindowState effectiveState(Qt::WindowStates state);
 
 // Store normal geometry used for saving application settings.
diff --git a/src/widgets/kernel/qwidgetwindow_qpa_p.h b/src/widgets/kernel/qwidgetwindow_qpa_p.h
index 8d6f14a669..06ba8ea646 100644
--- a/src/widgets/kernel/qwidgetwindow_qpa_p.h
+++ b/src/widgets/kernel/qwidgetwindow_qpa_p.h
@@ -101,6 +101,7 @@ protected:
 
 private slots:
     void updateObjectName();
+    void repaintWindow();
 
 private:
     void updateGeometry();