1 files changed, 83 insertions, 0 deletions
diff --git a/src/gui/painting/qrasterbackingstore.cpp b/src/gui/painting/qrasterbackingstore.cpp
new file mode 100644
index 0000000000..3b3ef2fd2e
--- /dev/null
+++ b/src/gui/painting/qrasterbackingstore.cpp
@@ -0,0 +1,83 @@
+// Copyright (C) 2016 The Qt Company Ltd.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
+
+#include "qrasterbackingstore_p.h"
+
+#include <QtGui/qbackingstore.h>
+#include <QtGui/qpainter.h>
+
+#include <private/qhighdpiscaling_p.h>
+#include <qpa/qplatformwindow.h>
+
+QT_BEGIN_NAMESPACE
+
+QRasterBackingStore::QRasterBackingStore(QWindow *window)
+    : QPlatformBackingStore(window)
+{
+}
+
+QRasterBackingStore::~QRasterBackingStore()
+{
+}
+
+void QRasterBackingStore::resize(const QSize &size, const QRegion &staticContents)
+{
+    Q_UNUSED(staticContents);
+    m_requestedSize = size;
+}
+
+QImage::Format QRasterBackingStore::format() const
+{
+    if (window()->format().hasAlpha())
+        return QImage::Format_ARGB32_Premultiplied;
+    else
+        return QImage::Format_RGB32;
+}
+
+QPaintDevice *QRasterBackingStore::paintDevice()
+{
+    return &m_image;
+}
+
+QImage QRasterBackingStore::toImage() const
+{
+    return m_image;
+}
+
+bool QRasterBackingStore::scroll(const QRegion &region, int dx, int dy)
+{
+    if (!QPlatformSurface::isRasterSurface(window()))
+        return false;
+
+    extern void qt_scrollRectInImage(QImage &, const QRect &, const QPoint &);
+
+    const qreal devicePixelRatio = m_image.devicePixelRatio();
+    const QPoint delta(dx * devicePixelRatio, dy * devicePixelRatio);
+
+    const QRect rect = region.boundingRect();
+    qt_scrollRectInImage(m_image, QRect(rect.topLeft() * devicePixelRatio, rect.size() * devicePixelRatio), delta);
+
+    return true;
+}
+
+void QRasterBackingStore::beginPaint(const QRegion &region)
+{
+    qreal nativeWindowDevicePixelRatio = window()->handle()->devicePixelRatio();
+    QSize effectiveBufferSize = m_requestedSize * nativeWindowDevicePixelRatio;
+    if (m_image.devicePixelRatio() != nativeWindowDevicePixelRatio || m_image.size() != effectiveBufferSize) {
+        m_image = QImage(effectiveBufferSize, format());
+        m_image.setDevicePixelRatio(nativeWindowDevicePixelRatio);
+        if (m_image.hasAlphaChannel())
+            m_image.fill(Qt::transparent);
+    }
+
+    if (!m_image.hasAlphaChannel())
+        return;
+
+    QPainter painter(&m_image);
+    painter.setCompositionMode(QPainter::CompositionMode_Source);
+    for (const QRect &rect : region)
+        painter.fillRect(rect, Qt::transparent);
+}
+
+QT_END_NAMESPACE