iOS: Switch backingstore to use raster paint engine, not GL

Now that more of the raster operations are NEON-optimized this should
be acceptable. The switch enables antialiased drawing, and makes iOS
in line with other platforms in having QBackingStore backed by a QImage.

The use of QImage also allows us to remove code from the backingstore
implementation that was only needed to support the composeAndFlush
code path.

The common parts of a raster backingstore implementation have been
factored out into QRasterBackingStore in platformsupport, which can
be shared with more platforms in the future.

[ChangeLog][iOS] QBackingStore now uses the raster paint engine
instead of the OpenGL paint engine, enabling improved antialiased
drawing. In case of performance regressions, the old code path
can be enabled by setting the window's surface type to
QSurface::OpenGLSurface.

Task-number: QTBUG-35271
Change-Id: Ia300b9a5edf8dc0b4bfb99d84ed3c23a8523c267
Reviewed-by: Laszlo Agocs <laszlo.agocs@theqtcompany.com>

1 files changed, 9 insertions, 12 deletions

diff --git a/src/plugins/platforms/ios/qiosbackingstore.h b/src/plugins/platforms/ios/qiosbackingstore.h
index 5d2ae429f1..387a286447 100644
--- a/src/plugins/platforms/ios/qiosbackingstore.h
+++ b/src/plugins/platforms/ios/qiosbackingstore.h
@@ -36,34 +36,31 @@
 
 #include <qpa/qplatformbackingstore.h>
 
+#include <QtPlatformSupport/private/qrasterbackingstore_p.h>
+
 QT_BEGIN_NAMESPACE
 
 class QOpenGLPaintDevice;
-class QOpenGLFramebufferObject;
-class QOffscreenSurface;
 
-class QIOSBackingStore : public QPlatformBackingStore
+class QIOSBackingStore : public QRasterBackingStore
 {
 public:
     QIOSBackingStore(QWindow *window);
     ~QIOSBackingStore();
 
-    QPaintDevice *paintDevice();
+    QPaintDevice *paintDevice() Q_DECL_OVERRIDE;
 
-    void beginPaint(const QRegion &);
-    void endPaint();
+    void beginPaint(const QRegion &) Q_DECL_OVERRIDE;
+    void endPaint() Q_DECL_OVERRIDE;
 
-    void flush(QWindow *window, const QRegion &region, const QPoint &offset);
-    void resize(const QSize &size, const QRegion &staticContents);
-    GLuint toTexture(const QRegion &dirtyRegion, QSize *textureSize, TextureFlags *flags) const;
+    void flush(QWindow *window, const QRegion &region, const QPoint &offset) Q_DECL_OVERRIDE;
+    void resize(const QSize &size, const QRegion &staticContents) Q_DECL_OVERRIDE;
 
     void makeCurrent();
 
 private:
     QOpenGLContext *m_context;
-    QOpenGLPaintDevice *m_device;
-    QOpenGLFramebufferObject *m_fbo;
-    QOffscreenSurface *m_surface;
+    QOpenGLPaintDevice *m_glDevice;
 };
 
 QT_END_NAMESPACE