[blitter] Work on tst_QPixmap::clear()

By default QPixmap may not hasAlphaChannel(), only if setMask()
or fill() with a transparent color is called a QPixmap will
hasAlphaChannel().

Make the QBlittablePlatformPixmap remember if there is an alpha
channel, pass this as parameter in createBlittable to make it
clear that this is required and not optional.

Update the DirectFB plugin to handle this parameter to create a
RGB32 or ARGB Surface depending on the alpha value, also only use
PreMultiplied alpha when using ARGB. Separate the two constructors
for the QDirectFbBlitter to either adopt a DirectFB Surface or to
create one.

Cherry-picked-from: qtbase:ab50b60f5cc237d5620f3ff3b2eb44c857f8f60b

Change-Id: I8abf82408ecd2d075fc6f241ace8be2a34ac56e7
Reviewed-by: Jørgen Lind <jorgen.lind@nokia.com>

Merge-request: 1492
Reviewed-by: Jørgen Lind <jorgen.lind@nokia.com>

1 files changed, 2 insertions, 1 deletions

diff --git a/src/gui/image/qpixmap_blitter_p.h b/src/gui/image/qpixmap_blitter_p.h
index 9b809caeb4..4742a83e13 100644
--- a/src/gui/image/qpixmap_blitter_p.h
+++ b/src/gui/image/qpixmap_blitter_p.h
@@ -55,7 +55,7 @@ public:
     QBlittablePixmapData();
     ~QBlittablePixmapData();
 
-    virtual QBlittable *createBlittable(const QSize &size) const = 0;
+    virtual QBlittable *createBlittable(const QSize &size, bool alpha) const = 0;
     QBlittable *blittable() const;
     void setBlittable(QBlittable *blittable);
 
@@ -85,6 +85,7 @@ public:
 protected:
     QScopedPointer<QBlitterPaintEngine> m_engine;
     QScopedPointer<QBlittable> m_blittable;
+    bool m_alpha;
 
 #ifdef QT_BLITTER_RASTEROVERLAY
     QImage *m_rasterOverlay;