Improve performance of VGPath creation by reusing the same path

The vgClearPath() function can be used to clear a path for reuse
more efficiently than destroying the path and creating a new one.

Task-number: QT-2974
Reviewed-by: Daniel Pope

1 files changed, 67 insertions, 57 deletions

diff --git a/src/openvg/qpaintengine_vg.cpp b/src/openvg/qpaintengine_vg.cpp
index da47f06..4192dbb 100644
--- a/src/openvg/qpaintengine_vg.cpp
+++ b/src/openvg/qpaintengine_vg.cpp
@@ -131,8 +131,9 @@ public:
     void draw(VGPath path, const QPen& pen, const QBrush& brush, VGint rule = VG_EVEN_ODD);
     void stroke(VGPath path, const QPen& pen);
     void fill(VGPath path, const QBrush& brush, VGint rule = VG_EVEN_ODD);
-    VGPath vectorPathToVGPath(const QVectorPath& path);
-    VGPath painterPathToVGPath(const QPainterPath& path);
+    inline void releasePath(VGPath path);
+    VGPath vectorPathToVGPath(const QVectorPath& path, bool forceNewPath = false);
+    VGPath painterPathToVGPath(const QPainterPath& path, bool forceNewPath = false);
     VGPath roundedRectPath(const QRectF &rect, qreal xRadius, qreal yRadius, Qt::SizeMode mode);
     VGPaintType setBrush
         (VGPaint paint, const QBrush& brush, VGMatrixMode mode,
@@ -178,6 +179,8 @@ public:
     VGPath roundRectPath;   // Cached path for quick drawing of rounded rects.
 #endif
 
+    VGPath reusablePath;    // Reusable path for vectorPathToVGPath(), etc.
+
     QTransform transform;   // Currently active transform.
     bool simpleTransform;   // True if the transform is simple (non-projective).
     qreal penScale;         // Pen scaling factor from "transform".
@@ -350,6 +353,8 @@ void QVGPaintEnginePrivate::init()
     roundRectPath = 0;
 #endif
 
+    reusablePath = 0;
+
     simpleTransform = true;
     pathTransformSet = false;
     penScale = 1.0;
@@ -446,6 +451,15 @@ void QVGPaintEnginePrivate::initObjects()
                             VG_PATH_CAPABILITY_ALL);
     vgAppendPathData(linePath, 2, segments, coords);
 #endif
+
+    // This path can be reused over and over by calling vgClearPath().
+    reusablePath = vgCreatePath(VG_PATH_FORMAT_STANDARD,
+                                VG_PATH_DATATYPE_F,
+                                1.0f,        // scale
+                                0.0f,        // bias
+                                32 + 1,      // segmentCapacityHint
+                                32 * 2,      // coordCapacityHint
+                                VG_PATH_CAPABILITY_ALL);
 }
 
 void QVGPaintEnginePrivate::destroy()
@@ -465,6 +479,8 @@ void QVGPaintEnginePrivate::destroy()
     if (roundRectPath)
         vgDestroyPath(roundRectPath);
 #endif
+    if (reusablePath)
+        vgDestroyPath(reusablePath);
 
 #if !defined(QVG_NO_DRAW_GLYPHS)
     QVGFontCache::Iterator it;
@@ -541,19 +557,32 @@ void QVGPaintEnginePrivate::updateTransform(QPaintDevice *pdev)
     qt_scaleForTransform(transform, &penScale);
 }
 
-VGPath QVGPaintEnginePrivate::vectorPathToVGPath(const QVectorPath& path)
+inline void QVGPaintEnginePrivate::releasePath(VGPath path)
+{
+    if (path == reusablePath)
+        vgClearPath(path, VG_PATH_CAPABILITY_ALL);
+    else
+        vgDestroyPath(path);
+}
+
+VGPath QVGPaintEnginePrivate::vectorPathToVGPath(const QVectorPath& path, bool forceNewPath)
 {
     int count = path.elementCount();
     const qreal *points = path.points();
     const QPainterPath::ElementType *elements = path.elements();
 
-    VGPath vgpath = vgCreatePath(VG_PATH_FORMAT_STANDARD,
-                                 VG_PATH_DATATYPE_F,
-                                 1.0f,        // scale
-                                 0.0f,        // bias
-                                 count + 1,   // segmentCapacityHint
-                                 count * 2,   // coordCapacityHint
-                                 VG_PATH_CAPABILITY_ALL);
+    VGPath vgpath;
+    if (forceNewPath) {
+        vgpath = vgCreatePath(VG_PATH_FORMAT_STANDARD,
+                              VG_PATH_DATATYPE_F,
+                              1.0f,        // scale
+                              0.0f,        // bias
+                              count + 1,   // segmentCapacityHint
+                              count * 2,   // coordCapacityHint
+                              VG_PATH_CAPABILITY_ALL);
+    } else {
+        vgpath = reusablePath;
+    }
 
     // Size is sufficient segments for drawRoundedRect() paths.
     QVarLengthArray<VGubyte, 20> segments;
@@ -725,17 +754,22 @@ VGPath QVGPaintEnginePrivate::vectorPathToVGPath(const QVectorPath& path)
     return vgpath;
 }
 
-VGPath QVGPaintEnginePrivate::painterPathToVGPath(const QPainterPath& path)
+VGPath QVGPaintEnginePrivate::painterPathToVGPath(const QPainterPath& path, bool forceNewPath)
 {
     int count = path.elementCount();
 
-    VGPath vgpath = vgCreatePath(VG_PATH_FORMAT_STANDARD,
-                                 VG_PATH_DATATYPE_F,
-                                 1.0f,        // scale
-                                 0.0f,        // bias
-                                 count + 1,   // segmentCapacityHint
-                                 count * 2,   // coordCapacityHint
-                                 VG_PATH_CAPABILITY_ALL);
+    VGPath vgpath;
+    if (forceNewPath) {
+        vgpath = vgCreatePath(VG_PATH_FORMAT_STANDARD,
+                              VG_PATH_DATATYPE_F,
+                              1.0f,        // scale
+                              0.0f,        // bias
+                              count + 1,   // segmentCapacityHint
+                              count * 2,   // coordCapacityHint
+                              VG_PATH_CAPABILITY_ALL);
+    } else {
+        vgpath = reusablePath;
+    }
 
     if (count == 0)
         return vgpath;
@@ -954,13 +988,7 @@ VGPath QVGPaintEnginePrivate::roundedRectPath(const QRectF &rect, qreal xRadius,
         vgModifyPathCoords(vgpath, 0, 9, pts);
     }
 #else
-    VGPath vgpath = vgCreatePath(VG_PATH_FORMAT_STANDARD,
-                                 VG_PATH_DATATYPE_F,
-                                 1.0f,        // scale
-                                 0.0f,        // bias
-                                 10,          // segmentCapacityHint
-                                 17 * 2,      // coordCapacityHint
-                                 VG_PATH_CAPABILITY_ALL);
+    VGPath vgpath = reusablePath;
     vgAppendPathData(vgpath, 10, roundedrect_types, pts);
 #endif
 
@@ -1516,7 +1544,7 @@ void QVGPaintEngine::draw(const QVectorPath &path)
         d->draw(vgpath, s->pen, s->brush, VG_EVEN_ODD);
     else
         d->draw(vgpath, s->pen, s->brush, VG_NON_ZERO);
-    vgDestroyPath(vgpath);
+    d->releasePath(vgpath);
 }
 
 void QVGPaintEngine::fill(const QVectorPath &path, const QBrush &brush)
@@ -1527,7 +1555,7 @@ void QVGPaintEngine::fill(const QVectorPath &path, const QBrush &brush)
         d->fill(vgpath, brush, VG_EVEN_ODD);
     else
         d->fill(vgpath, brush, VG_NON_ZERO);
-    vgDestroyPath(vgpath);
+    d->releasePath(vgpath);
 }
 
 void QVGPaintEngine::stroke(const QVectorPath &path, const QPen &pen)
@@ -1535,7 +1563,7 @@ void QVGPaintEngine::stroke(const QVectorPath &path, const QPen &pen)
     Q_D(QVGPaintEngine);
     VGPath vgpath = d->vectorPathToVGPath(path);
     d->stroke(vgpath, pen);
-    vgDestroyPath(vgpath);
+    d->releasePath(vgpath);
 }
 
 // Determine if a co-ordinate transform is simple enough to allow
@@ -1731,7 +1759,7 @@ void QVGPaintEngine::clip(const QVectorPath &path, Qt::ClipOperation op)
 
         default: break;
     }
-    vgDestroyPath(vgpath);
+    d->releasePath(vgpath);
 
     vgSeti(VG_MASKING, VG_TRUE);
     d->maskValid = true;
@@ -2048,7 +2076,7 @@ void QVGPaintEngine::clip(const QPainterPath &path, Qt::ClipOperation op)
 
         default: break;
     }
-    vgDestroyPath(vgpath);
+    d->releasePath(vgpath);
 
     vgSeti(VG_MASKING, VG_TRUE);
     d->maskValid = true;
@@ -2487,7 +2515,7 @@ void QVGPaintEngine::drawRoundedRect(const QRectF &rect, qreal xrad, qreal yrad,
         VGPath vgpath = d->roundedRectPath(rect, xrad, yrad, mode);
         d->draw(vgpath, s->pen, s->brush);
 #if defined(QVG_NO_MODIFY_PATH)
-        vgDestroyPath(vgpath);
+        d->releasePath(vgpath);
 #endif
     } else {
         QPaintEngineEx::drawRoundedRect(rect, xrad, yrad, mode);
@@ -2636,13 +2664,7 @@ void QVGPaintEngine::drawEllipse(const QRectF &r)
     Q_D(QVGPaintEngine);
     if (d->simpleTransform) {
         QVGPainterState *s = state();
-        VGPath path = vgCreatePath(VG_PATH_FORMAT_STANDARD,
-                                   VG_PATH_DATATYPE_F,
-                                   1.0f, // scale
-                                   0.0f, // bias
-                                   4,    // segmentCapacityHint
-                                   12,   // coordCapacityHint
-                                   VG_PATH_CAPABILITY_ALL);
+        VGPath path = d->reusablePath;
         static VGubyte segments[4] = {
             VG_MOVE_TO_ABS,
             VG_SCCWARC_TO_REL,
@@ -2666,7 +2688,7 @@ void QVGPaintEngine::drawEllipse(const QRectF &r)
         coords[11] = 0.0f;
         vgAppendPathData(path, 4, segments, coords);
         d->draw(path, s->pen, s->brush);
-        vgDestroyPath(path);
+        d->releasePath(path);
     } else {
         // The projective transform version of an ellipse is difficult.
         // Generate a QVectorPath containing cubic curves and transform that.
@@ -2690,7 +2712,7 @@ void QVGPaintEngine::drawPath(const QPainterPath &path)
         d->draw(vgpath, s->pen, s->brush, VG_EVEN_ODD);
     else
         d->draw(vgpath, s->pen, s->brush, VG_NON_ZERO);
-    vgDestroyPath(vgpath);
+    d->releasePath(vgpath);
 }
 
 void QVGPaintEngine::drawPoints(const QPointF *points, int pointCount)
@@ -2765,13 +2787,7 @@ void QVGPaintEngine::drawPolygon(const QPointF *points, int pointCount, PolygonD
 {
     Q_D(QVGPaintEngine);
     QVGPainterState *s = state();
-    VGPath path = vgCreatePath(VG_PATH_FORMAT_STANDARD,
-                               VG_PATH_DATATYPE_F,
-                               1.0f,             // scale
-                               0.0f,             // bias
-                               pointCount + 1,   // segmentCapacityHint
-                               pointCount * 2,   // coordCapacityHint
-                               VG_PATH_CAPABILITY_ALL);
+    VGPath path = d->reusablePath;
     QVarLengthArray<VGfloat, 16> coords;
     QVarLengthArray<VGubyte, 10> segments;
     for (int i = 0; i < pointCount; ++i, ++points) {
@@ -2805,20 +2821,14 @@ void QVGPaintEngine::drawPolygon(const QPointF *points, int pointCount, PolygonD
             d->draw(path, s->pen, s->brush, VG_EVEN_ODD);
             break;
     }
-    vgDestroyPath(path);
+    d->releasePath(path);
 }
 
 void QVGPaintEngine::drawPolygon(const QPoint *points, int pointCount, PolygonDrawMode mode)
 {
     Q_D(QVGPaintEngine);
     QVGPainterState *s = state();
-    VGPath path = vgCreatePath(VG_PATH_FORMAT_STANDARD,
-                               VG_PATH_DATATYPE_F,
-                               1.0f,             // scale
-                               0.0f,             // bias
-                               pointCount + 1,   // segmentCapacityHint
-                               pointCount * 2,   // coordCapacityHint
-                               VG_PATH_CAPABILITY_ALL);
+    VGPath path = d->reusablePath;
     QVarLengthArray<VGfloat, 16> coords;
     QVarLengthArray<VGubyte, 10> segments;
     for (int i = 0; i < pointCount; ++i, ++points) {
@@ -2852,7 +2862,7 @@ void QVGPaintEngine::drawPolygon(const QPoint *points, int pointCount, PolygonDr
             d->draw(path, s->pen, s->brush, VG_EVEN_ODD);
             break;
     }
-    vgDestroyPath(path);
+    d->releasePath(path);
 }
 
 void QVGPaintEnginePrivate::setImageOptions()
@@ -3251,7 +3261,7 @@ void QVGFontGlyphCache::cacheGlyphs
         ti.fontEngine->getUnscaledGlyph(glyph, &path, &metrics);
         VGPath vgPath;
         if (!path.isEmpty()) {
-            vgPath = d->painterPathToVGPath(path);
+            vgPath = d->painterPathToVGPath(path, true);
         } else {
             // Probably a "space" character with no visible outline.
             vgPath = VG_INVALID_HANDLE;