From cfc1658c68ee3b7227277a4549b60de545ec5f6f Mon Sep 17 00:00:00 2001
From: Gunnar Sletta <gunnar.sletta@nokia.com>
Date: Mon, 9 Aug 2010 14:03:45 +0200
Subject: Added QPainter::clipBoundingRect() which is significantly faster than
 QPainter::clipRegion().boundingRect().

Task: http://bugreports.qt.nokia.com/browse/QTBUG-12618
Reviewed-by: Kim
---
 src/gui/painting/qpainter.cpp        | 55 ++++++++++++++++++++++++++++++++++++
 src/gui/painting/qpainter.h          |  2 ++
 tests/auto/qpainter/tst_qpainter.cpp | 37 ++++++++++++++++++++++++
 3 files changed, 94 insertions(+)

diff --git a/src/gui/painting/qpainter.cpp b/src/gui/painting/qpainter.cpp
index f24eafd..c4de7f0 100644
--- a/src/gui/painting/qpainter.cpp
+++ b/src/gui/painting/qpainter.cpp
@@ -2702,6 +2702,61 @@ QPainterPath QPainter::clipPath() const
 }
 
 /*!
+    Returns the bounding rectangle of the current clip if there is a clip;
+    otherwise returns an empty rectangle. Note that the clip region is
+    given in logical coordinates.
+
+    The bounding rectangle is not guaranteed to be tight.
+
+    \sa setClipRect(), setClipPath(), setClipRegion()
+
+    \since 4.8
+ */
+
+QRectF QPainter::clipBoundingRect() const
+{
+    Q_D(const QPainter);
+
+    if (!d->engine) {
+        qWarning("QPainter::clipBoundingRect: Painter not active");
+        return QRectF();
+    }
+
+    // Accumulate the bounding box in device space. This is not 100%
+    // precise, but it fits within the guarantee and it is resonably
+    // fast.
+    QRectF bounds;
+    for (int i=0; i<d->state->clipInfo.size(); ++i) {
+         QRectF r;
+         const QPainterClipInfo &info = d->state->clipInfo.at(i);
+
+         if (info.clipType == QPainterClipInfo::RectClip)
+             r = info.rect;
+         else if (info.clipType == QPainterClipInfo::RegionClip)
+             r = info.region.boundingRect();
+         else
+             r = info.path.boundingRect();
+
+         r = info.matrix.mapRect(r);
+
+         if (i == 0)
+             bounds = r;
+         else if (info.operation == Qt::IntersectClip)
+             bounds &= r;
+         else if (info.operation == Qt::UniteClip)
+             bounds |= r;
+    }
+
+
+    // Map the rectangle back into logical space using the inverse
+    // matrix.
+    if (!d->txinv)
+        const_cast<QPainter *>(this)->d_ptr->updateInvMatrix();
+
+    return d->invMatrix.mapRect(bounds);
+}
+
+/*!
     \fn void QPainter::setClipRect(const QRectF &rectangle, Qt::ClipOperation operation)
 
     Enables clipping, and sets the clip region to the given \a
diff --git a/src/gui/painting/qpainter.h b/src/gui/painting/qpainter.h
index 85751a9..96305e3 100644
--- a/src/gui/painting/qpainter.h
+++ b/src/gui/painting/qpainter.h
@@ -222,6 +222,8 @@ public:
     void setClipping(bool enable);
     bool hasClipping() const;
 
+    QRectF clipBoundingRect() const;
+
     void save();
     void restore();
 
diff --git a/tests/auto/qpainter/tst_qpainter.cpp b/tests/auto/qpainter/tst_qpainter.cpp
index f358681..9ed212f 100644
--- a/tests/auto/qpainter/tst_qpainter.cpp
+++ b/tests/auto/qpainter/tst_qpainter.cpp
@@ -168,6 +168,8 @@ private slots:
 
     void clippedText();
 
+    void clipBoundingRect();
+
     void setOpacity_data();
     void setOpacity();
 
@@ -4522,6 +4524,41 @@ void tst_QPainter::QTBUG5939_attachPainterPrivate()
     QCOMPARE(widget->deviceTransform, proxy->deviceTransform);
 }
 
+void tst_QPainter::clipBoundingRect()
+{
+    QPixmap pix(500, 500);
+
+    QPainter p(&pix);
+
+    // Test a basic rectangle
+    p.setClipRect(100, 100, 200, 100);
+    QVERIFY(p.clipBoundingRect().contains(QRectF(100, 100, 200, 100)));
+    QVERIFY(!p.clipBoundingRect().contains(QRectF(50, 50, 300, 200)));
+    p.setClipRect(120, 120, 20, 20, Qt::IntersectClip);
+    QVERIFY(p.clipBoundingRect().contains(QRect(120, 120, 20, 20)));
+    QVERIFY(!p.clipBoundingRect().contains(QRectF(100, 100, 200, 100)));
+
+    // Test a basic path + region
+    QPainterPath path;
+    path.addRect(100, 100, 200, 100);
+    p.setClipPath(path);
+    QVERIFY(p.clipBoundingRect().contains(QRectF(100, 100, 200, 100)));
+    QVERIFY(!p.clipBoundingRect().contains(QRectF(50, 50, 300, 200)));
+    p.setClipRegion(QRegion(120, 120, 20, 20), Qt::IntersectClip);
+    QVERIFY(p.clipBoundingRect().contains(QRect(120, 120, 20, 20)));
+    QVERIFY(!p.clipBoundingRect().contains(QRectF(100, 100, 200, 100)));
+
+    p.setClipRect(0, 0, 500, 500);
+    p.translate(250, 250);
+    for (int i=0; i<360; ++i) {
+        p.rotate(1);
+        p.setClipRect(-100, -100, 200, 200, Qt::IntersectClip);
+    }
+    QVERIFY(p.clipBoundingRect().contains(QRectF(-100, -100, 200, 200)));
+    QVERIFY(!p.clipBoundingRect().contains(QRectF(-250, -250, 500, 500)));
+
+}
+
 QTEST_MAIN(tst_QPainter)
 
 #include "tst_qpainter.moc"
-- 
cgit v0.12