Optimized the bezier flattening a bit

Testcase with rounded rects went from 55 -> 62 FPS for 1000 random rects

Reviewed-By: Tom Cooksey

2 files changed, 17 insertions, 40 deletions

diff --git a/src/opengl/gl2paintengineex/qgl2pexvertexarray.cpp b/src/opengl/gl2paintengineex/qgl2pexvertexarray.cpp
index 1fe3999..e70b75e 100644
--- a/src/opengl/gl2paintengineex/qgl2pexvertexarray.cpp
+++ b/src/opengl/gl2paintengineex/qgl2pexvertexarray.cpp
@@ -120,8 +120,7 @@ void QGL2PEXVertexArray::addPath(const QVectorPath &path, GLfloat curveInverseSc
 //         qDebug("QVectorPath has element types");
 
         for (int i=1; i<path.elementCount(); ++i) {
-            const QPainterPath::ElementType elementType = elements[i];
-            switch (elementType) {
+            switch (elements[i]) {
             case QPainterPath::MoveToElement:
                 if (!outline)
                     addClosingLine(lastMoveTo);
@@ -137,11 +136,22 @@ void QGL2PEXVertexArray::addPath(const QVectorPath &path, GLfloat curveInverseSc
 //                qDebug("element[%d] is a LineToElement", i);
                 lineToArray(points[i].x(), points[i].y());
                 break;
-            case QPainterPath::CurveToElement:
-//                qDebug("element[%d] is a CurveToElement", i);
-                curveToArray(points[i], points[i+1], points[i+2], curveInverseScale);
-                i+=2;
-                break;
+            case QPainterPath::CurveToElement: {
+                QBezier b = QBezier::fromPoints(*(((const QPointF *) points) + i - 1),
+                                                points[i],
+                                                points[i+1],
+                                                points[i+2]);
+                QRectF bounds = b.bounds();
+                // threshold based on same algorithm as in qtriangulatingstroker.cpp
+                int threshold = qMin<float>(64, qMax(bounds.width(), bounds.height()) * 3.14f / (curveInverseScale * 8));
+                if (threshold < 3) threshold = 3;
+                qreal one_over_threshold_minus_1 = 1.f / (threshold - 1);
+                for (int t=0; t<threshold; ++t) {
+                    QPointF pt = b.pointAt(t * one_over_threshold_minus_1);
+                    lineToArray(pt.x(), pt.y());
+                }
+                i += 2;
+                break; }
             default:
                 break;
             }
@@ -167,35 +177,4 @@ void QGL2PEXVertexArray::lineToArray(const GLfloat x, const GLfloat y)
         minY = y;
 }
 
-void QGL2PEXVertexArray::curveToArray(const QGLPoint &cp1, const QGLPoint &cp2, const QGLPoint &ep, GLfloat inverseScale)
-{
-    qreal inverseScaleHalf = inverseScale / 2;
-
-    QBezier beziers[32];
-    beziers[0] = QBezier::fromPoints(vertexArray.last(), cp1, cp2, ep);
-    QBezier *b = beziers;
-    while (b >= beziers) {
-        // check if we can pop the top bezier curve from the stack
-        qreal l = qAbs(b->x4 - b->x1) + qAbs(b->y4 - b->y1);
-        qreal d;
-        if (l > inverseScale) {
-            d = qAbs( (b->x4 - b->x1)*(b->y1 - b->y2) - (b->y4 - b->y1)*(b->x1 - b->x2) )
-                + qAbs( (b->x4 - b->x1)*(b->y1 - b->y3) - (b->y4 - b->y1)*(b->x1 - b->x3) );
-            d /= l;
-        } else {
-            d = qAbs(b->x1 - b->x2) + qAbs(b->y1 - b->y2) +
-                qAbs(b->x1 - b->x3) + qAbs(b->y1 - b->y3);
-        }
-        if (d < inverseScaleHalf || b == beziers + 31) {
-            // good enough, we pop it off and add the endpoint
-            lineToArray(b->x4, b->y4);
-            --b;
-        } else {
-            // split, second half of the polygon goes lower into the stack
-            b->split(b+1, b);
-           ++b;
-        }
-    }
-}
-
 QT_END_NAMESPACE
diff --git a/src/opengl/gl2paintengineex/qgl2pexvertexarray_p.h b/src/opengl/gl2paintengineex/qgl2pexvertexarray_p.h
index 719904f..c53ef11 100644
--- a/src/opengl/gl2paintengineex/qgl2pexvertexarray_p.h
+++ b/src/opengl/gl2paintengineex/qgl2pexvertexarray_p.h
@@ -123,8 +123,6 @@ private:
     GLfloat     minY;
     bool        boundingRectDirty;
 
-    inline void curveToArray(const QGLPoint &cp1, const QGLPoint &cp2, const QGLPoint &ep, GLfloat inverseScale);
-
     void addClosingLine(int index);
     void addCentroid(const QVectorPath &path, int subPathIndex);
 };