Optimize QGraphicsItemEffectSourcePrivate::pixmap() for QGraphicsPixmapItems.

Even for DeviceCoordinate mode we can return the raw pixmap if the
graphics item size is untransformed.

Reviewed-by: Bjørn Erik Nilsen

2 files changed, 60 insertions, 7 deletions

diff --git a/src/gui/graphicsview/qgraphicsitem.cpp b/src/gui/graphicsview/qgraphicsitem.cpp
index d955f16..b6820f7 100644
--- a/src/gui/graphicsview/qgraphicsitem.cpp
+++ b/src/gui/graphicsview/qgraphicsitem.cpp
@@ -10717,7 +10717,6 @@ QPixmap QGraphicsItemEffectSourcePrivate::pixmap(Qt::CoordinateSystem system, QP
         qWarning("QGraphicsEffectSource::pixmap: Not yet implemented, lacking device context");
         return QPixmap();
     }
-
     if (!item->d_ptr->scene)
         return QPixmap();
     QGraphicsScenePrivate *scened = item->d_ptr->scene->d_func();
@@ -10725,9 +10724,11 @@ QPixmap QGraphicsItemEffectSourcePrivate::pixmap(Qt::CoordinateSystem system, QP
     const QRectF sourceRect = boundingRect(system);
     QRectF effectRectF;
 
+    bool unpadded = false;
     if (mode == QGraphicsEffect::PadToEffectiveBoundingRect) {
         if (info) {
             effectRectF = item->graphicsEffect()->boundingRectFor(boundingRect(Qt::DeviceCoordinates));
+            unpadded = (effectRectF.size() == sourceRect.size());
             if (info && system == Qt::LogicalCoordinates)
                 effectRectF = info->painter->worldTransform().inverted().mapRect(effectRectF);
         } else {
@@ -10739,6 +10740,7 @@ QPixmap QGraphicsItemEffectSourcePrivate::pixmap(Qt::CoordinateSystem system, QP
         effectRectF = sourceRect.adjusted(-1.5, -1.5, 1.5, 1.5);
     } else {
         effectRectF = sourceRect;
+        unpadded = true;
     }
 
     QRect effectRect = effectRectF.toAlignedRect();
@@ -10746,6 +10748,14 @@ QPixmap QGraphicsItemEffectSourcePrivate::pixmap(Qt::CoordinateSystem system, QP
     if (offset)
         *offset = effectRect.topLeft();
 
+    bool untransformed = !deviceCoordinates
+            || info->painter->worldTransform().type() <= QTransform::TxTranslate;
+    if (untransformed && unpadded && isPixmap()) {
+        if (offset)
+            *offset = boundingRect(system).topLeft().toPoint();
+        return static_cast<QGraphicsPixmapItem *>(item)->pixmap();
+    }
+
     if (deviceCoordinates) {
         // Clip to viewport rect.
         int left, top, right, bottom;
@@ -10773,12 +10783,6 @@ QPixmap QGraphicsItemEffectSourcePrivate::pixmap(Qt::CoordinateSystem system, QP
     if (effectRect.isEmpty())
         return QPixmap();
 
-    if (system == Qt::LogicalCoordinates
-        && effectRect.size() == sourceRect.size()
-        && isPixmap()) {
-        return static_cast<QGraphicsPixmapItem *>(item)->pixmap();
-    }
-
     QPixmap pixmap(effectRect.size());
     pixmap.fill(Qt::transparent);
     QPainter pixmapPainter(&pixmap);
diff --git a/tests/auto/qgraphicseffect/tst_qgraphicseffect.cpp b/tests/auto/qgraphicseffect/tst_qgraphicseffect.cpp
index 259df4d..69fc118 100644
--- a/tests/auto/qgraphicseffect/tst_qgraphicseffect.cpp
+++ b/tests/auto/qgraphicseffect/tst_qgraphicseffect.cpp
@@ -69,6 +69,7 @@ private slots:
     void opacity();
     void grayscale();
     void colorize();
+    void drawPixmapItem();
 };
 
 void tst_QGraphicsEffect::initTestCase()
@@ -465,6 +466,54 @@ void tst_QGraphicsEffect::colorize()
     QCOMPARE(image.pixel(10, 10), qRgb(122, 193, 66));
 }
 
+class PixmapItemEffect : public QGraphicsEffect
+{
+public:
+    PixmapItemEffect(const QPixmap &source)
+        : QGraphicsEffect()
+        , pixmap(source)
+        , repaints(0)
+    {}
+
+    QRectF boundingRectFor(const QRectF &rect) const
+    { return rect; }
+
+    void draw(QPainter *painter)
+    {
+        QVERIFY(sourcePixmap(Qt::LogicalCoordinates).pixmapData() == pixmap.pixmapData());
+        QVERIFY((painter->worldTransform().type() <= QTransform::TxTranslate) == (sourcePixmap(Qt::DeviceCoordinates).pixmapData() == pixmap.pixmapData()));
+
+        ++repaints;
+    }
+    QPixmap pixmap;
+    int repaints;
+};
+
+void tst_QGraphicsEffect::drawPixmapItem()
+{
+    QImage image(32, 32, QImage::Format_RGB32);
+    QPainter p(&image);
+    p.fillRect(0, 0, 32, 16, Qt::blue);
+    p.fillRect(0, 16, 32, 16, Qt::red);
+    p.end();
+
+    QGraphicsScene scene;
+    QGraphicsPixmapItem *item = new QGraphicsPixmapItem(QPixmap::fromImage(image));
+    scene.addItem(item);
+
+    PixmapItemEffect *effect = new PixmapItemEffect(item->pixmap());
+    item->setGraphicsEffect(effect);
+
+    QGraphicsView view(&scene);
+    view.show();
+    QTest::qWaitForWindowShown(&view);
+
+    item->rotate(180);
+    QTest::qWait(50);
+
+    QTRY_VERIFY(effect->repaints >= 2);
+}
+
 QTEST_MAIN(tst_QGraphicsEffect)
 #include "tst_qgraphicseffect.moc"