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Fix: QPainter off-by-one clipping for some non-integer scalings

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For some scalings, setClipRect(QRect) would produce a clip one pixel
different from setClipRect(QRectF) because of different
rounding. Ditto for setClipRegion. Fix by making sure to transform
QRectFs instead of QRects.

Fixes: QTBUG-78962
Fixes: QTBUG-78963
Change-Id: I0be721133858c30769ec6d81e978962a3d6b70cf
Reviewed-by: Christoph Cullmann <cullmann@kde.org>
Reviewed-by: Allan Sandfeld Jensen <allan.jensen@qt.io>
This commit is contained in:
Eirik Aavitsland 2019-10-17 13:25:06 +02:00
parent 14b61d48e8
commit 19f29802bf
3 changed files with 51 additions and 4 deletions
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2
src/gui/painting/qpaintengine_raster.cpp
View File

@ -1319,7 +1319,7 @@ void QRasterPaintEngine::clip(const QRect &rect, Qt::ClipOperation op)
QPaintEngineEx::clip(rect, op);
return;
} else if (!setClipRectInDeviceCoords(s->matrix.mapRect(rect), op)) {
} else if (!setClipRectInDeviceCoords(s->matrix.mapRect(QRectF(rect)).toRect(), op)) {
QPaintEngineEx::clip(rect, op);
return;
}

4
src/gui/painting/qtransform.cpp
View File

@ -1529,12 +1529,12 @@ QRegion QTransform::map(const QRegion &r) const
QRegion res;
if (m11() < 0 || m22() < 0) {
for (const QRect &rect : r)
res += mapRect(rect);
res += mapRect(QRectF(rect)).toRect();
} else {
QVarLengthArray<QRect, 32> rects;
rects.reserve(r.rectCount());
for (const QRect &rect : r) {
QRect nr = mapRect(rect);
QRect nr = mapRect(QRectF(rect)).toRect();
if (!nr.isEmpty())
rects.append(nr);
}

49
tests/auto/gui/painting/qpainter/tst_qpainter.cpp
View File

@ -157,10 +157,10 @@ private slots:
void clippedLines();
void clippedPolygon_data();
void clippedPolygon();
void clippedText();
void clipBoundingRect();
void transformedClip();
void setOpacity_data();
void setOpacity();
@ -4589,6 +4589,53 @@ void tst_QPainter::clipBoundingRect()
}
void tst_QPainter::transformedClip()
{
QImage img(8, 4, QImage::Format_ARGB32_Premultiplied);
QImage img2(img.size(), img.format());
QRect clip(0, 0, 2, 1);
QTransform xf;
xf.translate(0.2, 0);
xf.scale(2.2, 1);
// setClipRect(QRectF)
{
img.fill(Qt::green);
QPainter p(&img);
p.setTransform(xf);
p.setClipRect(QRectF(clip));
p.fillRect(img.rect(), Qt::white);
}
// setClipRect(QRect)
{
img2.fill(Qt::green);
QPainter p(&img2);
p.setTransform(xf);
p.setClipRect(clip);
p.fillRect(img2.rect(), Qt::white);
QCOMPARE(img, img2);
}
// setClipRegion
{
img2.fill(Qt::green);
QPainter p(&img2);
p.setTransform(xf);
p.setClipRegion(QRegion(clip) + QRect(0, 3, 1, 1)); // dummy extra rect to avoid single-rect codepath
p.fillRect(img2.rect(), Qt::white);
QCOMPARE(img.copy(0, 0, 8, 2), img2.copy(0, 0, 8, 2));
}
// setClipPath
{
img2.fill(Qt::green);
QPainter p(&img2);
p.setTransform(xf);
QPainterPath path;
path.addRect(clip);
p.setClipPath(path);
p.fillRect(img2.rect(), Qt::white);
QCOMPARE(img, img2);
}
}
#if defined(Q_OS_MAC)
// Only Mac supports sub pixel positions in raster engine currently
void tst_QPainter::drawText_subPixelPositionsInRaster_qtbug5053()