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Be more precise in calculating start point of fast scaling 

We were using low precision dx/dy for calculating the starting point which
meant we could be off when clipping at high scale factors.

Fixes: QTBUG-60782
Change-Id: I883f9aed1346fdffae070b6316ea808b83519701
Reviewed-by: Eirik Aavitsland <eirik.aavitsland@qt.io>
bb10
Allan Sandfeld Jensen 2019-04-02 18:03:01 +02:00
parent ce7f14d2e0
commit 8374b4016e
1 changed files with 30 additions and 89 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

119
src/gui/painting/qblendfunctions_p.h
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@ -65,11 +65,11 @@ void qt_scale_image_16bit(uchar *destPixels, int dbpl,
const QRect &clip,
T blender)
{
qreal sx = targetRect.width() / (qreal) srcRect.width();
qreal sy = targetRect.height() / (qreal) srcRect.height();
qreal sx = srcRect.width() / (qreal) targetRect.width();
qreal sy = srcRect.height() / (qreal) targetRect.height();
int ix = 0x00010000 / sx;
int iy = 0x00010000 / sy;
const int ix = 0x00010000 * sx;
const int iy = 0x00010000 * sy;
// qDebug() << "scale:" << endl
// << " - target" << targetRect << endl
@ -77,59 +77,30 @@ void qt_scale_image_16bit(uchar *destPixels, int dbpl,
// << " - clip" << clip << endl
// << " - sx=" << sx << " sy=" << sy << " ix=" << ix << " iy=" << iy;
int cx1 = clip.x();
int cx2 = clip.x() + clip.width();
int cy1 = clip.top();
int cy2 = clip.y() + clip.height();
int tx1 = qRound(targetRect.left());
int tx2 = qRound(targetRect.right());
int ty1 = qRound(targetRect.top());
int ty2 = qRound(targetRect.bottom());
if (tx2 < tx1)
qSwap(tx2, tx1);
if (ty2 < ty1)
qSwap(ty2, ty1);
if (tx1 < cx1)
tx1 = cx1;
if (tx2 >= cx2)
tx2 = cx2;
if (tx1 >= tx2)
QRect tr = targetRect.normalized().toRect();
tr = tr.intersected(clip);
if (tr.isEmpty())
return;
if (ty1 < cy1)
ty1 = cy1;
if (ty2 >= cy2)
ty2 = cy2;
if (ty1 >= ty2)
return;
int h = ty2 - ty1;
int w = tx2 - tx1;
const int tx1 = tr.left();
const int ty1 = tr.top();
int h = tr.height();
int w = tr.width();
quint32 basex;
quint32 srcy;
if (sx < 0) {
int dstx = qFloor((tx1 + qreal(0.5) - targetRect.right()) * ix) + 1;
int dstx = qFloor((tx1 + qreal(0.5) - targetRect.right()) * sx * 65536) + 1;
basex = quint32(srcRect.right() * 65536) + dstx;
} else {
int dstx = qCeil((tx1 + qreal(0.5) - targetRect.left()) * ix) - 1;
int dstx = qCeil((tx1 + qreal(0.5) - targetRect.left()) * sx * 65536) - 1;
basex = quint32(srcRect.left() * 65536) + dstx;
}
if (sy < 0) {
int dsty = qFloor((ty1 + qreal(0.5) - targetRect.bottom()) * iy) + 1;
int dsty = qFloor((ty1 + qreal(0.5) - targetRect.bottom()) * sy * 65536) + 1;
srcy = quint32(srcRect.bottom() * 65536) + dsty;
} else {
int dsty = qCeil((ty1 + qreal(0.5) - targetRect.top()) * iy) - 1;
int dsty = qCeil((ty1 + qreal(0.5) - targetRect.top()) * sy * 65536) - 1;
srcy = quint32(srcRect.top() * 65536) + dsty;
}
@ -185,11 +156,11 @@ template <typename T> void qt_scale_image_32bit(uchar *destPixels, int dbpl,
const QRect &clip,
T blender)
{
qreal sx = targetRect.width() / (qreal) srcRect.width();
qreal sy = targetRect.height() / (qreal) srcRect.height();
qreal sx = srcRect.width() / (qreal) targetRect.width();
qreal sy = srcRect.height() / (qreal) targetRect.height();
int ix = 0x00010000 / sx;
int iy = 0x00010000 / sy;
const int ix = 0x00010000 * sx;
const int iy = 0x00010000 * sy;
// qDebug() << "scale:" << endl
// << " - target" << targetRect << endl
@ -197,60 +168,30 @@ template <typename T> void qt_scale_image_32bit(uchar *destPixels, int dbpl,
// << " - clip" << clip << endl
// << " - sx=" << sx << " sy=" << sy << " ix=" << ix << " iy=" << iy;
int cx1 = clip.x();
int cx2 = clip.x() + clip.width();
int cy1 = clip.top();
int cy2 = clip.y() + clip.height();
int tx1 = qRound(targetRect.left());
int tx2 = qRound(targetRect.right());
int ty1 = qRound(targetRect.top());
int ty2 = qRound(targetRect.bottom());
if (tx2 < tx1)
qSwap(tx2, tx1);
if (ty2 < ty1)
qSwap(ty2, ty1);
if (tx1 < cx1)
tx1 = cx1;
if (tx2 >= cx2)
tx2 = cx2;
if (tx1 >= tx2)
return;
if (ty1 < cy1)
ty1 = cy1;
if (ty2 >= cy2)
ty2 = cy2;
if (ty1 >= ty2)
return;
int h = ty2 - ty1;
int w = tx2 - tx1;
if (!w || !h)
QRect tr = targetRect.normalized().toRect();
tr = tr.intersected(clip);
if (tr.isEmpty())
return;
const int tx1 = tr.left();
const int ty1 = tr.top();
int h = tr.height();
int w = tr.width();
quint32 basex;
quint32 srcy;
if (sx < 0) {
int dstx = qFloor((tx1 + qreal(0.5) - targetRect.right()) * ix) + 1;
int dstx = qFloor((tx1 + qreal(0.5) - targetRect.right()) * sx * 65536) + 1;
basex = quint32(srcRect.right() * 65536) + dstx;
} else {
int dstx = qCeil((tx1 + qreal(0.5) - targetRect.left()) * ix) - 1;
int dstx = qCeil((tx1 + qreal(0.5) - targetRect.left()) * sx * 65536) - 1;
basex = quint32(srcRect.left() * 65536) + dstx;
}
if (sy < 0) {
int dsty = qFloor((ty1 + qreal(0.5) - targetRect.bottom()) * iy) + 1;
int dsty = qFloor((ty1 + qreal(0.5) - targetRect.bottom()) * sy * 65536) + 1;
srcy = quint32(srcRect.bottom() * 65536) + dsty;
} else {
int dsty = qCeil((ty1 + qreal(0.5) - targetRect.top()) * iy) - 1;
int dsty = qCeil((ty1 + qreal(0.5) - targetRect.top()) * sy * 65536) - 1;
srcy = quint32(srcRect.top() * 65536) + dsty;
}