Add devicePixelRatio support to the Windows QPA plugin.

This adds support for the environment variable
QT_DEVICE_PIXEL_RATIO for the Windows platform plugin.

Task-number: QTBUG-38993
Task-number: QTBUG-38858
Change-Id: I6831eb6d3a09a80be7bbef46395e91531b61cc50
Reviewed-by: Alessandro Portale <alessandro.portale@digia.com>
Reviewed-by: Paul Olav Tvete <paul.tvete@digia.com>

1 files changed, 7 insertions, 1 deletions

diff --git a/src/plugins/platforms/windows/qwindowsbackingstore.h b/src/plugins/platforms/windows/qwindowsbackingstore.h
index e19b8a4db1..9c9500dabb 100644
--- a/src/plugins/platforms/windows/qwindowsbackingstore.h
+++ b/src/plugins/platforms/windows/qwindowsbackingstore.h
@@ -43,6 +43,7 @@
 #define QWINDOWSBACKINGSTORE_H
 
 #include "qtwindows_additional.h"
+#include "qwindowsscaling.h"
 
 #include <qpa/qplatformbackingstore.h>
 #include <QtCore/QScopedPointer>
@@ -60,7 +61,12 @@ public:
     ~QWindowsBackingStore();
 
     QPaintDevice *paintDevice() Q_DECL_OVERRIDE;
-    void flush(QWindow *window, const QRegion &region, const QPoint &offset) Q_DECL_OVERRIDE;
+    void flush(QWindow *window, const QRegion &region, const QPoint &offset) Q_DECL_OVERRIDE
+    {
+        flushDp(window, QWindowsScaling::mapToNative(region.boundingRect()),
+                offset * QWindowsScaling::factor());
+    }
+    void flushDp(QWindow *window, const QRect &boundingRect, const QPoint &offset);
     void resize(const QSize &size, const QRegion &r) Q_DECL_OVERRIDE;
     bool scroll(const QRegion &area, int dx, int dy) Q_DECL_OVERRIDE;
     void beginPaint(const QRegion &) Q_DECL_OVERRIDE;