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

3 files changed, 15 insertions, 11 deletions

diff --git a/src/opengl/gl2paintengineex/qglengineshadermanager.cpp b/src/opengl/gl2paintengineex/qglengineshadermanager.cpp
index e22303d..af9306f 100644
--- a/src/opengl/gl2paintengineex/qglengineshadermanager.cpp
+++ b/src/opengl/gl2paintengineex/qglengineshadermanager.cpp
@@ -476,7 +476,7 @@ bool QGLEngineShaderManager::useCorrectShaderProg()
         return false;
 
     bool useCustomSrc = customSrcStage != 0;
-    if (useCustomSrc && srcPixelType != QGLEngineShaderManager::ImageSrc) {
+    if (useCustomSrc && srcPixelType != QGLEngineShaderManager::ImageSrc && srcPixelType != Qt::TexturePattern) {
         useCustomSrc = false;
         qWarning("QGLEngineShaderManager - Ignoring custom shader stage for non image src");
     }
diff --git a/src/opengl/gl2paintengineex/qglengineshadersource_p.h b/src/opengl/gl2paintengineex/qglengineshadersource_p.h
index 3eef808..2407979 100644
--- a/src/opengl/gl2paintengineex/qglengineshadersource_p.h
+++ b/src/opengl/gl2paintengineex/qglengineshadersource_p.h
@@ -258,7 +258,7 @@ static const char* const qglslPositionWithTextureBrushVertexShader = "\
     uniform   mediump vec2  halfViewportSize; \
     uniform   highp   vec2  invertedTextureSize; \
     uniform   highp   mat3  brushTransform; \
-    varying   highp   vec2  brushTextureCoords; \
+    varying   highp   vec2  textureCoords; \
     void setPosition(void) { \
             gl_Position = pmvMatrix * vertexCoordsArray;\
             gl_Position.xy = gl_Position.xy / gl_Position.w; \
@@ -267,7 +267,7 @@ static const char* const qglslPositionWithTextureBrushVertexShader = "\
             mediump float invertedHTexCoordsZ = 1.0 / hTexCoords.z; \
             gl_Position.xy = gl_Position.xy * invertedHTexCoordsZ; \
             gl_Position.w = invertedHTexCoordsZ; \
-            brushTextureCoords.xy = (hTexCoords.xy * invertedTextureSize) * gl_Position.w; \
+            textureCoords.xy = (hTexCoords.xy * invertedTextureSize) * gl_Position.w; \
     }";
 
 static const char* const qglslAffinePositionWithTextureBrushVertexShader
@@ -278,26 +278,26 @@ static const char* const qglslAffinePositionWithTextureBrushVertexShader
 // we emulate GL_REPEAT by only taking the fractional part of the texture coords.
 // TODO: Special case POT textures which don't need this emulation
 static const char* const qglslTextureBrushSrcFragmentShader = "\
-    varying highp   vec2      brushTextureCoords; \
+    varying highp   vec2      textureCoords; \
     uniform lowp    sampler2D brushTexture; \
     lowp vec4 srcPixel() { \
-        return texture2D(brushTexture, fract(brushTextureCoords)); \
+        return texture2D(brushTexture, fract(textureCoords)); \
     }";
 #else
 static const char* const qglslTextureBrushSrcFragmentShader = "\
-    varying highp   vec2      brushTextureCoords; \
+    varying highp   vec2      textureCoords; \
     uniform lowp    sampler2D brushTexture; \
     lowp vec4 srcPixel() { \
-        return texture2D(brushTexture, brushTextureCoords); \
+        return texture2D(brushTexture, textureCoords); \
     }";
 #endif
 
 static const char* const qglslTextureBrushSrcWithPatternFragmentShader = "\
-    varying highp   vec2      brushTextureCoords; \
+    varying highp   vec2      textureCoords; \
     uniform lowp    vec4      patternColor; \
     uniform lowp    sampler2D brushTexture; \
     lowp vec4 srcPixel() { \
-        return patternColor * (1.0 - texture2D(brushTexture, brushTextureCoords).r); \
+        return patternColor * (1.0 - texture2D(brushTexture, textureCoords).r); \
     }";
 
 // Solid Fill Brush
diff --git a/src/opengl/gl2paintengineex/qpaintengineex_opengl2.cpp b/src/opengl/gl2paintengineex/qpaintengineex_opengl2.cpp
index b70810d..a9744b3 100644
--- a/src/opengl/gl2paintengineex/qpaintengineex_opengl2.cpp
+++ b/src/opengl/gl2paintengineex/qpaintengineex_opengl2.cpp
@@ -535,7 +535,7 @@ void QGL2PaintEngineExPrivate::updateBrushUniforms()
                 shaderManager->currentProgram()->setUniformValue(location(QGLEngineShaderManager::PatternColor), col);
             }
 
-            QSizeF invertedTextureSize(1.0 / texPixmap.width(), 1.0 * textureInvertedY / texPixmap.height());
+            QSizeF invertedTextureSize(1.0 / texPixmap.width(), 1.0 / texPixmap.height());
             shaderManager->currentProgram()->setUniformValue(location(QGLEngineShaderManager::InvertedTextureSize), invertedTextureSize);
 
             QVector2D halfViewportSize(width*0.5, height*0.5);
@@ -550,7 +550,11 @@ void QGL2PaintEngineExPrivate::updateBrushUniforms()
 
         QTransform translate(1, 0, 0, 1, -translationPoint.x(), -translationPoint.y());
         QTransform gl_to_qt(1, 0, 0, -1, 0, height);
-        QTransform inv_matrix = gl_to_qt * (brushQTransform * matrix).inverted() * translate;
+        QTransform inv_matrix;
+        if (style == Qt::TexturePattern && textureInvertedY == -1)
+            inv_matrix = gl_to_qt * (QTransform(1, 0, 0, -1, 0, currentBrush->texture().height()) * brushQTransform * matrix).inverted() * translate;
+        else
+            inv_matrix = gl_to_qt * (brushQTransform * matrix).inverted() * translate;
 
         shaderManager->currentProgram()->setUniformValue(location(QGLEngineShaderManager::BrushTransform), inv_matrix);
         shaderManager->currentProgram()->setUniformValue(location(QGLEngineShaderManager::BrushTexture), QT_BRUSH_TEXTURE_UNIT);