AuroraMiddleware/qt5base-lts
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Fix scaling precision with large zooms

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Avoid using the two fast-scaling paths, while they might not overflow
in this case, they do not have enough precision in their fixed point
math to render accurately.

Task-number: QTBUG-53582
Change-Id: I2e063ee90defbecd79a12a6ce02a74c60d1805df
Reviewed-by: Eirik Aavitsland <eirik.aavitsland@qt.io>
This commit is contained in:
Allan Sandfeld Jensen 2017-12-12 12:07:38 +01:00
parent 951e204b29
commit 5473535344
1 changed files with 12 additions and 4 deletions
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16
src/gui/painting/qpaintengine_raster.cpp
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@ -2341,8 +2341,12 @@ void QRasterPaintEngine::drawImage(const QRectF &r, const QImage &img, const QRe
if (s->matrix.type() > QTransform::TxTranslate || stretch_sr) {
QRectF targetBounds = s->matrix.mapRect(r);
bool exceedsPrecision = targetBounds.width() > 0x7fff
|| targetBounds.height() > 0x7fff;
bool exceedsPrecision = r.width() > 0x7fff
|| r.height() > 0x7fff
|| targetBounds.width() > 0x7fff
|| targetBounds.height() > 0x7fff
|| s->matrix.m11() >= 512
|| s->matrix.m22() >= 512;
if (!exceedsPrecision && d->canUseFastImageBlending(d->rasterBuffer->compositionMode, img)) {
if (s->matrix.type() > QTransform::TxScale) {
@ -4639,9 +4643,13 @@ void QSpanData::setupMatrix(const QTransform &matrix, int bilin)
bilinear = bilin;
const bool affine = inv.isAffine();
const qreal f1 = m11 * m11 + m21 * m21;
const qreal f2 = m12 * m12 + m22 * m22;
fast_matrix = affine
&& m11 * m11 + m21 * m21 < 1e4
&& m12 * m12 + m22 * m22 < 1e4
&& f1 < 1e4
&& f2 < 1e4
&& f1 > (1.0 / 65536)
&& f2 > (1.0 / 65536)
&& qAbs(dx) < 1e4
&& qAbs(dy) < 1e4;