Direct2D QPA: Optimize Clipping

Use axis aligned clips when possible instead of layer-clipping. This can
be much faster when a lot of clipping operations take place.

Change-Id: I6865d69fc917a7da858033b4c362b307724d9006
Reviewed-by: Risto Avila <risto.avila@digia.com>
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@digia.com>
Reviewed-by: Andrew Knight <andrew.knight@digia.com>

2 files changed, 32 insertions, 29 deletions

diff --git a/src/gui/painting/qpaintengine_raster.cpp b/src/gui/painting/qpaintengine_raster.cpp
index bfcb24ae3a..ce8c1d1ca7 100644
--- a/src/gui/painting/qpaintengine_raster.cpp
+++ b/src/gui/painting/qpaintengine_raster.cpp
@@ -1,6 +1,6 @@
 /****************************************************************************
 **
-** Copyright (C) 2013 Digia Plc and/or its subsidiary(-ies).
+** Copyright (C) 2014 Digia Plc and/or its subsidiary(-ies).
 ** Contact: http://www.qt-project.org/legal
 **
 ** This file is part of the QtGui module of the Qt Toolkit.
@@ -235,21 +235,6 @@ static const QRectF boundingRect(const QPointF *points, int pointCount)
 }
 #endif
 
-template <typename T> static inline bool isRect(const T *pts, int elementCount) {
-    return (elementCount == 5 // 5-point polygon, check for closed rect
-            && pts[0] == pts[8] && pts[1] == pts[9] // last point == first point
-            && pts[0] == pts[6] && pts[2] == pts[4] // x values equal
-            && pts[1] == pts[3] && pts[5] == pts[7] // y values equal...
-            && pts[0] < pts[4] && pts[1] < pts[5]
-            ) ||
-           (elementCount == 4 // 4-point polygon, check for unclosed rect
-            && pts[0] == pts[6] && pts[2] == pts[4] // x values equal
-            && pts[1] == pts[3] && pts[5] == pts[7] // y values equal...
-            && pts[0] < pts[4] && pts[1] < pts[5]
-            );
-}
-
-
 static void qt_ft_outline_move_to(qfixed x, qfixed y, void *data)
 {
     ((QOutlineMapper *) data)->moveTo(QPointF(qt_fixed_to_real(x), qt_fixed_to_real(y)));
@@ -1193,22 +1178,14 @@ void QRasterPaintEngine::clip(const QVectorPath &path, Qt::ClipOperation op)
     Q_D(QRasterPaintEngine);
     QRasterPaintEngineState *s = state();
 
-    const qreal *points = path.points();
-    const QPainterPath::ElementType *types = path.elements();
-
     // There are some cases that are not supported by clip(QRect)
     if (op != Qt::IntersectClip || !s->clip || s->clip->hasRectClip || s->clip->hasRegionClip) {
         if (s->matrix.type() <= QTransform::TxScale
-            && ((path.shape() == QVectorPath::RectangleHint)
-                || (isRect(points, path.elementCount())
-                    && (!types || (types[0] == QPainterPath::MoveToElement
-                                   && types[1] == QPainterPath::LineToElement
-                                   && types[2] == QPainterPath::LineToElement
-                                   && types[3] == QPainterPath::LineToElement))))) {
+            && path.isRect()) {
 #ifdef QT_DEBUG_DRAW
             qDebug() << " --- optimizing vector clip to rect clip...";
 #endif
-
+            const qreal *points = path.points();
             QRectF r(points[0], points[1], points[4]-points[0], points[5]-points[1]);
             if (setClipRectInDeviceCoords(s->matrix.mapRect(r).toRect(), op))
                 return;
@@ -1939,7 +1916,7 @@ void QRasterPaintEngine::drawPolygon(const QPointF *points, int pointCount, Poly
 #endif
     Q_ASSERT(pointCount >= 2);
 
-    if (mode != PolylineMode && isRect((qreal *) points, pointCount)) {
+    if (mode != PolylineMode && QVectorPath::isRect((qreal *) points, pointCount)) {
         QRectF r(points[0], points[2]);
         drawRects(&r, 1);
         return;
@@ -1980,7 +1957,7 @@ void QRasterPaintEngine::drawPolygon(const QPoint *points, int pointCount, Polyg
         qDebug() << "   - " << points[i];
 #endif
     Q_ASSERT(pointCount >= 2);
-    if (mode != PolylineMode && isRect((int *) points, pointCount)) {
+    if (mode != PolylineMode && QVectorPath::isRect((int *) points, pointCount)) {
         QRect r(points[0].x(),
                 points[0].y(),
                 points[2].x() - points[0].x(),
diff --git a/src/gui/painting/qvectorpath_p.h b/src/gui/painting/qvectorpath_p.h
index e97d6e1dce..ca95c32597 100644
--- a/src/gui/painting/qvectorpath_p.h
+++ b/src/gui/painting/qvectorpath_p.h
@@ -1,6 +1,6 @@
 /****************************************************************************
 **
-** Copyright (C) 2013 Digia Plc and/or its subsidiary(-ies).
+** Copyright (C) 2014 Digia Plc and/or its subsidiary(-ies).
 ** Contact: http://www.qt-project.org/legal
 **
 ** This file is part of the QtGui module of the Qt Toolkit.
@@ -167,6 +167,32 @@ public:
         return 0;
     }
 
+    template <typename T> static inline bool isRect(const T *pts, int elementCount) {
+        return (elementCount == 5 // 5-point polygon, check for closed rect
+                && pts[0] == pts[8] && pts[1] == pts[9] // last point == first point
+                && pts[0] == pts[6] && pts[2] == pts[4] // x values equal
+                && pts[1] == pts[3] && pts[5] == pts[7] // y values equal...
+                && pts[0] < pts[4] && pts[1] < pts[5]
+                ) ||
+               (elementCount == 4 // 4-point polygon, check for unclosed rect
+                && pts[0] == pts[6] && pts[2] == pts[4] // x values equal
+                && pts[1] == pts[3] && pts[5] == pts[7] // y values equal...
+                && pts[0] < pts[4] && pts[1] < pts[5]
+                );
+    }
+
+    inline bool isRect() const
+    {
+        const QPainterPath::ElementType * const types = elements();
+
+        return (shape() == QVectorPath::RectangleHint)
+                || (isRect(points(), elementCount())
+                    && (!types || (types[0] == QPainterPath::MoveToElement
+                                   && types[1] == QPainterPath::LineToElement
+                                   && types[2] == QPainterPath::LineToElement
+                                   && types[3] == QPainterPath::LineToElement)));
+    }
+
 
 private:
     Q_DISABLE_COPY(QVectorPath)