Added some optimizations to the blur and drop shadow GL filters.

* Use ExpandToTransparentBorderPadMode since we can use GL_CLAMP_TO_EDGE
  to clamp to the texture.

* Shrink the bounding rects reported by the blur
  and drop shadow filters (expanding by 2 * radius isn't needed).

* Use a single-pass blur for radii <= 3 to avoid the overhead of
  rendering to an FBO.

* Made the fast blur setting generate filters for only a predefined set
  of radii, and then use the actual blur radius to spread the sample
  points outwards.

* Optimized the generated program to rely less on temporary variables,
  as those seemed to not be handled very well by certain GLSL compilers.

Reviewed-by: Gunnar Sletta

1 files changed, 2 insertions, 1 deletions

diff --git a/src/gui/graphicsview/qgraphicsitem.cpp b/src/gui/graphicsview/qgraphicsitem.cpp
index 7d9390c..738c6e3 100644
--- a/src/gui/graphicsview/qgraphicsitem.cpp
+++ b/src/gui/graphicsview/qgraphicsitem.cpp
@@ -10703,7 +10703,8 @@ QPixmap QGraphicsItemEffectSourcePrivate::pixmap(Qt::CoordinateSystem system, QP
     if (mode == QGraphicsEffectSource::ExpandToEffectRectPadMode) {
         effectRect = item->graphicsEffect()->boundingRectFor(sourceRect).toAlignedRect();
     } else if (mode == QGraphicsEffectSource::ExpandToTransparentBorderPadMode) {
-        effectRect = sourceRect.adjusted(-1, -1, 1, 1).toAlignedRect();
+        // adjust by 1.5 to account for cosmetic pens
+        effectRect = sourceRect.adjusted(-1.5, -1.5, 1.5, 1.5).toAlignedRect();
     } else {
         effectRect = sourceRect.toAlignedRect();
     }