1 files changed, 68 insertions, 0 deletions
diff --git a/src/gui/painting/qrhibackingstore.cpp b/src/gui/painting/qrhibackingstore.cpp
new file mode 100644
index 0000000000..586dfb44a4
--- /dev/null
+++ b/src/gui/painting/qrhibackingstore.cpp
@@ -0,0 +1,68 @@
+// Copyright (C) 2022 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 "qrhibackingstore_p.h"
+#include <private/qimage_p.h>
+
+QT_BEGIN_NAMESPACE
+
+QRhiBackingStore::QRhiBackingStore(QWindow *window)
+    : QRasterBackingStore(window)
+{
+}
+
+QRhiBackingStore::~QRhiBackingStore()
+{
+}
+
+void QRhiBackingStore::flush(QWindow *flushedWindow, const QRegion &region, const QPoint &offset)
+{
+    Q_UNUSED(region);
+    Q_UNUSED(offset);
+
+    if (flushedWindow->surfaceType() != window()->surfaceType()) {
+        qWarning() << "Cannot flush child window" << flushedWindow
+            << "with surface type" << flushedWindow->surfaceType() << ";"
+            << "Must match" << window()->surfaceType() << "of" << window();
+
+        // FIXME: Support different surface types by not tying the
+        // RHI config to the backing store itself (per window config).
+        return;
+    }
+
+    if (!rhi()) {
+        QPlatformBackingStoreRhiConfig rhiConfig;
+        switch (window()->surfaceType()) {
+        case QSurface::OpenGLSurface:
+            rhiConfig.setApi(QPlatformBackingStoreRhiConfig::OpenGL);
+            break;
+        case QSurface::MetalSurface:
+            rhiConfig.setApi(QPlatformBackingStoreRhiConfig::Metal);
+            break;
+        default:
+            Q_UNREACHABLE();
+        }
+        rhiConfig.setEnabled(true);
+        setRhiConfig(rhiConfig);
+    }
+
+    static QPlatformTextureList emptyTextureList;
+    bool translucentBackground = m_image.hasAlphaChannel();
+    rhiFlush(flushedWindow, flushedWindow->devicePixelRatio(),
+        region, offset, &emptyTextureList, translucentBackground);
+}
+
+QImage::Format QRhiBackingStore::format() const
+{
+    QImage::Format fmt = QRasterBackingStore::format();
+
+    // With render-to-texture widgets and QRhi-based flushing the backingstore
+    // image must have an alpha channel. Hence upgrading the format. Matches
+    // what other platforms (Windows, xcb) do.
+    if (QImage::toPixelFormat(fmt).alphaUsage() != QPixelFormat::UsesAlpha)
+        fmt = qt_maybeDataCompatibleAlphaVersion(fmt);
+
+    return fmt;
+}
+
+QT_END_NAMESPACE