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Avoid overflows in gradient calculations

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Avoid the optimized fixed-point function for vertical gradients if the
parameters are out of range for that. Fall back to the general
gradient function in that case.

Fixes: QTBUG-120331
Pick-to: 6.5 6.2
Change-Id: Idf116f0077403531d9ea414e3043fdc92b6fe4a9
Reviewed-by: Eskil Abrahamsen Blomfeldt <eskil.abrahamsen-blomfeldt@qt.io>
Reviewed-by: Allan Sandfeld Jensen <allan.jensen@qt.io>
(cherry picked from commit ade33a91442f8085a7ddeb8e6fdf33463103b119)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>
This commit is contained in:
Eirik Aavitsland 2024-02-27 15:45:39 +01:00 committed by Qt Cherry-pick Bot
parent d77e099200
commit f02ccd86c7
1 changed files with 44 additions and 25 deletions
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69
src/gui/painting/qdrawhelper.cpp
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@ -4973,16 +4973,11 @@ void qBlendTexture(int count, const QT_FT_Span *spans, void *userData)
proc(count, spans, userData);
}
static void blend_vertical_gradient_argb(int count, const QT_FT_Span *spans, void *userData)
static inline bool calculate_fixed_gradient_factors(int count, const QT_FT_Span *spans,
const QSpanData *data,
const LinearGradientValues &linear,
int *pyinc, int *poff)
{
QSpanData *data = reinterpret_cast<QSpanData *>(userData);
LinearGradientValues linear;
getLinearGradientValues(&linear, data);
CompositionFunctionSolid funcSolid =
functionForModeSolid[data->rasterBuffer->compositionMode];
/*
The logic for vertical gradient calculations is a mathematically
reduced copy of that in fetchLinearGradient() - which is basically:
@ -4997,8 +4992,32 @@ static void blend_vertical_gradient_argb(int count, const QT_FT_Span *spans, voi
This has then been converted to fixed point to improve performance.
*/
const int gss = GRADIENT_STOPTABLE_SIZE - 1;
int yinc = int((linear.dy * data->m22 * gss) * FIXPT_SIZE);
int off = int((((linear.dy * (data->m22 * qreal(0.5) + data->dy) + linear.off) * gss) * FIXPT_SIZE));
qreal ryinc = linear.dy * data->m22 * gss * FIXPT_SIZE;
qreal roff = (linear.dy * (data->m22 * qreal(0.5) + data->dy) + linear.off) * gss * FIXPT_SIZE;
const int limit = std::numeric_limits<int>::max() - FIXPT_SIZE;
if (count && (std::fabs(ryinc) < limit) && (std::fabs(roff) < limit)
&& (std::fabs(ryinc * spans->y + roff) < limit)
&& (std::fabs(ryinc * (spans + count - 1)->y + roff) < limit)) {
*pyinc = int(ryinc);
*poff = int(roff);
return true;
}
return false;
}
static bool blend_vertical_gradient_argb(int count, const QT_FT_Span *spans, void *userData)
{
QSpanData *data = reinterpret_cast<QSpanData *>(userData);
LinearGradientValues linear;
getLinearGradientValues(&linear, data);
CompositionFunctionSolid funcSolid =
functionForModeSolid[data->rasterBuffer->compositionMode];
int yinc(0), off(0);
if (!calculate_fixed_gradient_factors(count, spans, data, linear, &yinc, &off))
return false;
while (count--) {
int y = spans->y;
@ -5011,21 +5030,20 @@ static void blend_vertical_gradient_argb(int count, const QT_FT_Span *spans, voi
funcSolid(dst, spans->len, color, spans->coverage);
++spans;
}
return true;
}
template<ProcessSpans blend_color>
static void blend_vertical_gradient(int count, const QT_FT_Span *spans, void *userData)
static bool blend_vertical_gradient(int count, const QT_FT_Span *spans, void *userData)
{
QSpanData *data = reinterpret_cast<QSpanData *>(userData);
LinearGradientValues linear;
getLinearGradientValues(&linear, data);
// Based on the same logic as blend_vertical_gradient_argb.
const int gss = GRADIENT_STOPTABLE_SIZE - 1;
int yinc = int((linear.dy * data->m22 * gss) * FIXPT_SIZE);
int off = int((((linear.dy * (data->m22 * qreal(0.5) + data->dy) + linear.off) * gss) * FIXPT_SIZE));
int yinc(0), off(0);
if (!calculate_fixed_gradient_factors(count, spans, data, linear, &yinc, &off))
return false;
while (count--) {
int y = spans->y;
@ -5038,6 +5056,7 @@ static void blend_vertical_gradient(int count, const QT_FT_Span *spans, void *us
blend_color(1, spans, userData);
++spans;
}
return true;
}
void qBlendGradient(int count, const QT_FT_Span *spans, void *userData)
@ -5052,8 +5071,8 @@ void qBlendGradient(int count, const QT_FT_Span *spans, void *userData)
break;
case QImage::Format_RGB32:
case QImage::Format_ARGB32_Premultiplied:
if (isVerticalGradient)
return blend_vertical_gradient_argb(count, spans, userData);
if (isVerticalGradient && blend_vertical_gradient_argb(count, spans, userData))
return;
return blend_src_generic(count, spans, userData);
#if defined(__SSE2__) || defined(__ARM_NEON__) || (Q_PROCESSOR_WORDSIZE == 8)
case QImage::Format_ARGB32:
@ -5075,8 +5094,8 @@ void qBlendGradient(int count, const QT_FT_Span *spans, void *userData)
case QImage::Format_RGBA32FPx4_Premultiplied:
#endif
#if QT_CONFIG(raster_64bit)
if (isVerticalGradient)
return blend_vertical_gradient<blend_color_generic_rgb64>(count, spans, userData);
if (isVerticalGradient && blend_vertical_gradient<blend_color_generic_rgb64>(count, spans, userData))
return;
return blend_src_generic_rgb64(count, spans, userData);
#endif // QT_CONFIG(raster_64bit)
#if QT_CONFIG(raster_fp)
@ -5086,13 +5105,13 @@ void qBlendGradient(int count, const QT_FT_Span *spans, void *userData)
case QImage::Format_RGBX32FPx4:
case QImage::Format_RGBA32FPx4:
case QImage::Format_RGBA32FPx4_Premultiplied:
if (isVerticalGradient)
return blend_vertical_gradient<blend_color_generic_fp>(count, spans, userData);
if (isVerticalGradient && blend_vertical_gradient<blend_color_generic_fp>(count, spans, userData))
return;
return blend_src_generic_fp(count, spans, userData);
#endif
default:
if (isVerticalGradient)
return blend_vertical_gradient<blend_color_generic>(count, spans, userData);
if (isVerticalGradient && blend_vertical_gradient<blend_color_generic>(count, spans, userData))
return;
return blend_src_generic(count, spans, userData);
}
Q_UNREACHABLE();