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qpa: Fix rendering issue in blitter engine (negative scaling factors) 

A 180° rotation results in a TxScale QTransform with negative scaling
factors (x=-1.0 y=-1.0). This is not properly handled by blitter paint
engine yet, so use software rendering fallback in this case.

This rendering issue can be seen when using "-webkit-transform" CSS
property in WebKit with DirectFB QPA platform.

Change-Id: Iee496b6bf0c90ffe36c4235ceaa2c80f296b2ca4
Reviewed-by: Samuel Rødal <samuel.rodal@digia.com>
bb10
Julien Brianceau 2012-11-07 11:01:08 +01:00 committed by The Qt Project
parent 2027f204b5
commit 07ea3cf0b3
2 changed files with 40 additions and 1 deletions
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6
src/gui/painting/qpaintengine_blitter.cpp
View File

@ -330,7 +330,11 @@ void QBlitterPaintEnginePrivate::updateTransformState(QPainterState *s)
{
QTransform::TransformationType type = s->matrix.type();
caps.updateState(STATE_XFORM_COMPLEX, type > QTransform::TxScale);
// consider scaling operations with a negative factor as "complex" for now.
// as some blitters could handle axisymmetrical operations, we should improve blitter
// paint engine to handle them as a capability
caps.updateState(STATE_XFORM_COMPLEX, (type > QTransform::TxScale) ||
((type == QTransform::TxScale) && ((s->matrix.m11() < 0.0) || (s->matrix.m22() < 0.0))));
caps.updateState(STATE_XFORM_SCALE, type > QTransform::TxTranslate);
hasXForm = type >= QTransform::TxTranslate;

35
tests/auto/gui/painting/qpainter/tst_qpainter.cpp
View File

@ -113,6 +113,7 @@ private slots:
void drawBorderPixmap();
#endif
void drawPixmapFragments();
void drawPixmapNegativeScale();
void drawLine_data();
void drawLine();
@ -803,6 +804,40 @@ void tst_QPainter::drawPixmapFragments()
QVERIFY(fragment.opacity == 1);
}
void tst_QPainter::drawPixmapNegativeScale()
{
// basePixmap is a 16x16 opaque white square ...
QPixmap basePixmap(16, 16);
basePixmap.fill(QColor(255, 255, 255, 255));
// ... with an opaque black 8x16 left strip
QPainter p(&basePixmap);
p.setCompositionMode(QPainter::CompositionMode_Source);
p.fillRect(QRect(0, 0, 8, 16), QColor(0, 0, 0, 255));
p.end();
// verify one pixel value for each strip
QImage baseImage = basePixmap.toImage().convertToFormat(QImage::Format_ARGB32);
QVERIFY(baseImage.pixel(4, 8) == qRgba(0, 0, 0, 255));
QVERIFY(baseImage.pixel(12, 8) == qRgba(255, 255, 255, 255));
// resultPixmap is a 16x16 square
QPixmap resultPixmap(16, 16);
// draw basePixmap over resultPixmap using x=-1.0 y=-1.0
// scaling factors (i.e. 180° rotation)
QPainter p2(&resultPixmap);
p2.setCompositionMode(QPainter::CompositionMode_Source);
p2.scale(qreal(-1.0), qreal(-1.0));
p2.translate(-resultPixmap.width(), -resultPixmap.height());
p2.drawPixmap(resultPixmap.rect(), basePixmap);
p2.end();
// check result
QImage resultImage = resultPixmap.toImage().convertToFormat(QImage::Format_ARGB32);
QVERIFY(resultImage.pixel(4, 8) == qRgba(255, 255, 255, 255)); // left strip is now white
QVERIFY(resultImage.pixel(12, 8) == qRgba(0, 0, 0, 255)); // and right strip is now black
}
void tst_QPainter::drawLine_data()
{
QTest::addColumn<QLine>("line");