Move the 0.5 offset we add for aliased rendering to updateMatrix()

The old code set and unset a temporary matrix for every draw command
when doing aliased rendering. Instead, we just use a flag to indicate
that updateMatrix() should add the offset. This means the offset is
added only once. When doing lots of small rendering operations on a
(non-multisampled) QGLWidget, this gives up to 72% performance boost
on the SGX.

Reviewed-By: Kim

2 files changed, 47 insertions, 33 deletions

diff --git a/src/opengl/gl2paintengineex/qpaintengineex_opengl2.cpp b/src/opengl/gl2paintengineex/qpaintengineex_opengl2.cpp
index 32fa3dc..bfc640f 100644
--- a/src/opengl/gl2paintengineex/qpaintengineex_opengl2.cpp
+++ b/src/opengl/gl2paintengineex/qpaintengineex_opengl2.cpp
@@ -608,12 +608,18 @@ void QGL2PaintEngineExPrivate::updateMatrix()
     const GLfloat wfactor = 2.0f / width;
     const GLfloat hfactor = -2.0f / height;
 
+    if (addOffset) {
+        pmvMatrix[2][0] = (wfactor * (transform.dx() + 0.49f)) - transform.m33();
+        pmvMatrix[2][1] = (hfactor * (transform.dy() + 0.49f)) + transform.m33();
+    } else {
+        pmvMatrix[2][0] = (wfactor * transform.dx()) - transform.m33();
+        pmvMatrix[2][1] = (hfactor * transform.dy()) + transform.m33();
+    }
+
     pmvMatrix[0][0] = (wfactor * transform.m11())  - transform.m13();
     pmvMatrix[1][0] = (wfactor * transform.m21())  - transform.m23();
-    pmvMatrix[2][0] = (wfactor * transform.dx() )  - transform.m33();
     pmvMatrix[0][1] = (hfactor * transform.m12())  + transform.m13();
     pmvMatrix[1][1] = (hfactor * transform.m22())  + transform.m23();
-    pmvMatrix[2][1] = (hfactor * transform.dy() )  + transform.m33();
     pmvMatrix[0][2] = transform.m13();
     pmvMatrix[1][2] = transform.m23();
     pmvMatrix[2][2] = transform.m33();
@@ -705,6 +711,12 @@ void QGL2PaintEngineExPrivate::drawTexture(const QGLRect& dest, const QGLRect& s
     // Setup for texture drawing
     currentBrush = noBrush;
     shaderManager->setSrcPixelType(pattern ? QGLEngineShaderManager::PatternSrc : QGLEngineShaderManager::ImageSrc);
+
+    if (addOffset) {
+        addOffset = false;
+        matrixDirty = true;
+    }
+
     if (prepareForDraw(opaque))
         shaderManager->currentProgram()->setUniformValue(location(QGLEngineShaderManager::ImageTexture), QT_IMAGE_TEXTURE_UNIT);
 
@@ -867,6 +879,16 @@ void QGL2PaintEngineExPrivate::fill(const QVectorPath& path)
 {
     transferMode(BrushDrawingMode);
 
+    const QOpenGL2PaintEngineState *s = q->state();
+    const bool newAddOffset = !(s->renderHints & QPainter::Antialiasing) &&
+                              (qbrush_style(currentBrush) == Qt::SolidPattern) &&
+                              !multisamplingAlwaysEnabled;
+
+    if (addOffset != newAddOffset) {
+        addOffset = newAddOffset;
+        matrixDirty = true;
+    }
+
     // Might need to call updateMatrix to re-calculate inverseScale
     if (matrixDirty)
         updateMatrix();
@@ -1278,31 +1300,14 @@ void QGL2PaintEngineEx::fill(const QVectorPath &path, const QBrush &brush)
 {
     Q_D(QGL2PaintEngineEx);
 
-    Qt::BrushStyle style = qbrush_style(brush);
-    if (style == Qt::NoBrush)
+    if (qbrush_style(brush) == Qt::NoBrush)
         return;
+
     if (!d->inRenderText)
         ensureActive();
 
-    QOpenGL2PaintEngineState *s = state();
-    bool doOffset = !(s->renderHints & QPainter::Antialiasing) &&
-                    (style == Qt::SolidPattern) &&
-                    !d->multisamplingAlwaysEnabled;
-
-    if (doOffset) {
-        d->temporaryTransform = s->matrix;
-        QTransform tx = QTransform::fromTranslate(.49, .49);
-        s->matrix = s->matrix * tx;
-        d->matrixDirty = true;
-    }
-
     d->setBrush(brush);
     d->fill(path);
-
-    if (doOffset) {
-        s->matrix = d->temporaryTransform;
-        d->matrixDirty = true;
-    }
 }
 
 extern bool qt_scaleForTransform(const QTransform &transform, qreal *scale); // qtransform.cpp
@@ -1326,11 +1331,9 @@ void QGL2PaintEngineEx::stroke(const QVectorPath &path, const QPen &pen)
 
     ensureActive();
 
-    bool doOffset = !(s->renderHints & QPainter::Antialiasing) && !d->multisamplingAlwaysEnabled;
-    if (doOffset) {
-        d->temporaryTransform = s->matrix;
-        QTransform tx = QTransform::fromTranslate(0.49, .49);
-        s->matrix = s->matrix * tx;
+    const bool newAddOffset = !(s->renderHints & QPainter::Antialiasing) && !d->multisamplingAlwaysEnabled;
+    if (d->addOffset != newAddOffset) {
+        d->addOffset = newAddOffset;
         d->matrixDirty = true;
     }
 
@@ -1401,11 +1404,6 @@ void QGL2PaintEngineEx::stroke(const QVectorPath &path, const QPen &pen)
 
         d->updateClipScissorTest();
     }
-
-    if (doOffset) {
-        s->matrix = d->temporaryTransform;
-        d->matrixDirty = true;
-    }
 }
 
 void QGL2PaintEngineEx::penChanged() { }
@@ -1613,6 +1611,11 @@ void QGL2PaintEngineExPrivate::drawCachedGlyphs(const QPointF &p, QFontEngineGly
     if (textureCoordinateArray.data() != oldTextureCoordinateDataPtr)
         glVertexAttribPointer(QT_TEXTURE_COORDS_ATTR, 2, GL_FLOAT, GL_FALSE, 0, textureCoordinateArray.data());
 
+    if (addOffset) {
+        addOffset = false;
+        matrixDirty = true;
+    }
+
     QBrush pensBrush = q->state()->pen.brush();
     setBrush(pensBrush);
 
@@ -1725,6 +1728,11 @@ void QGL2PaintEngineEx::drawPixmaps(const QDrawPixmaps::Data *drawingData, int d
     d->textureCoordinateArray.clear();
     d->opacityArray.reset();
 
+    if (d->addOffset) {
+        d->addOffset = false;
+        d->matrixDirty = true;
+    }
+
     bool allOpaque = true;
 
     for (int i = 0; i < dataCount; ++i) {
@@ -2006,6 +2014,11 @@ void QGL2PaintEngineExPrivate::writeClip(const QVectorPath &path, uint value)
 {
     transferMode(BrushDrawingMode);
 
+    if (addOffset) {
+        addOffset = false;
+        matrixDirty = true;
+    }
+
     if (matrixDirty)
         updateMatrix();
 
diff --git a/src/opengl/gl2paintengineex/qpaintengineex_opengl2_p.h b/src/opengl/gl2paintengineex/qpaintengineex_opengl2_p.h
index 8de4a82..4ace030 100644
--- a/src/opengl/gl2paintengineex/qpaintengineex_opengl2_p.h
+++ b/src/opengl/gl2paintengineex/qpaintengineex_opengl2_p.h
@@ -171,6 +171,7 @@ public:
             q(q_ptr),
             width(0), height(0),
             ctx(0),
+            addOffset(false),
             inverseScale(1),
             shaderManager(0),
             inRenderText(false)
@@ -246,8 +247,6 @@ public:
     QBrush currentBrush; // May not be the state's brush!
     const QBrush noBrush;
 
-    GLfloat     inverseScale;
-
     QGL2PEXVertexArray vertexCoordinateArray;
     QGL2PEXVertexArray textureCoordinateArray;
     QDataBuffer<GLfloat> opacityArray;
@@ -255,7 +254,9 @@ public:
     GLfloat staticVertexCoordinateArray[8];
     GLfloat staticTextureCoordinateArray[8];
 
+    bool addOffset; // When enabled, adds a 0.49,0.49 offset to matrix in updateMatrix
     GLfloat pmvMatrix[3][3];
+    GLfloat inverseScale;
 
     QGLEngineShaderManager* shaderManager;