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Fix blending of RGB32 on RGB32 with partial opacity

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The alpha channel of an RGB32 image was not properly ignored when doing
blending with partial opacity.

Now the alpha value is properly ignored, which is both more correct
and faster. This also makes SSE2 and AVX2 implementations match NEON
which was already doing the right thing (though had dead code for
doing it wrong).

Change-Id: I4613b8d70ed8c2e36ced10baaa7a4a55bd36a940
Reviewed-by: Eirik Aavitsland <eirik.aavitsland@qt.io>
This commit is contained in:
Allan Sandfeld Jensen 2016-11-18 16:33:12 +01:00
parent 5cc1265c34
commit e3b6f6d165
5 changed files with 45 additions and 26 deletions
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30
src/gui/painting/qblendfunctions.cpp
View File

@ -385,19 +385,25 @@ void qt_blend_rgb32_on_rgb32(uchar *destPixels, int dbpl,
destPixels, dbpl, srcPixels, sbpl, w, h, const_alpha);
fflush(stdout);
#endif
if (const_alpha != 256) {
qt_blend_argb32_on_argb32(destPixels, dbpl, srcPixels, sbpl, w, h, const_alpha);
return;
}
const uint *src = (const uint *) srcPixels;
uint *dst = (uint *) destPixels;
int len = w * 4;
for (int y=0; y<h; ++y) {
memcpy(dst, src, len);
dst = (quint32 *)(((uchar *) dst) + dbpl);
src = (const quint32 *)(((const uchar *) src) + sbpl);
if (const_alpha == 256) {
const int len = w * 4;
for (int y = 0; y < h; ++y) {
memcpy(dst, src, len);
dst = (quint32 *)(((uchar *) dst) + dbpl);
src = (const quint32 *)(((const uchar *) src) + sbpl);
}
return;
} else if (const_alpha != 0) {
const_alpha = (const_alpha * 255) >> 8;
int ialpha = 255 - const_alpha;
for (int y=0; y<h; ++y) {
for (int x=0; x<w; ++x)
dst[x] = INTERPOLATE_PIXEL_255(dst[x], ialpha, src[x], const_alpha);
dst = (quint32 *)(((uchar *) dst) + dbpl);
src = (const quint32 *)(((const uchar *) src) + sbpl);
}
}
}
@ -414,7 +420,7 @@ struct Blend_RGB32_on_RGB32_ConstAlpha {
}
inline void write(quint32 *dst, quint32 src) {
*dst = BYTE_MUL(src, m_alpha) + BYTE_MUL(*dst, m_ialpha);
*dst = INTERPOLATE_PIXEL_255(src, m_alpha, *dst, m_ialpha);
}
inline void flush(void *) {}

8
src/gui/painting/qdrawhelper_avx2.cpp
View File

@ -267,11 +267,9 @@ void qt_blend_rgb32_on_rgb32_avx2(uchar *destPixels, int dbpl,
// 2) interpolate pixels with AVX2
for (; x < (w - 7); x += 8) {
const __m256i srcVector = _mm256_lddqu_si256((const __m256i *)&src[x]);
if (!_mm256_testz_si256(srcVector, srcVector)) {
__m256i dstVector = _mm256_load_si256((__m256i *)&dst[x]);
INTERPOLATE_PIXEL_255_AVX2(srcVector, dstVector, constAlphaVector, oneMinusConstAlpha, colorMask, half);
_mm256_store_si256((__m256i *)&dst[x], dstVector);
}
__m256i dstVector = _mm256_load_si256((__m256i *)&dst[x]);
INTERPOLATE_PIXEL_255_AVX2(srcVector, dstVector, constAlphaVector, oneMinusConstAlpha, colorMask, half);
_mm256_store_si256((__m256i *)&dst[x], dstVector);
}
// 3) Epilogue

2
src/gui/painting/qdrawhelper_neon.cpp
View File

@ -523,8 +523,6 @@ void qt_blend_rgb32_on_rgb32_neon(uchar *destPixels, int dbpl,
vst1q_u32((uint32_t *)&dst[x], vcombine_u32(result32_low, result32_high));
}
for (; x<w; ++x) {
uint s = src[x];
s = BYTE_MUL(s, const_alpha);
dst[x] = INTERPOLATE_PIXEL_255(src[x], const_alpha, dst[x], one_minus_const_alpha);
}
dst = (quint32 *)(((uchar *) dst) + dbpl);

11
src/gui/painting/qdrawhelper_sse2.cpp
View File

@ -101,7 +101,6 @@ void qt_blend_rgb32_on_rgb32_sse2(uchar *destPixels, int dbpl,
quint32 *dst = (quint32 *) destPixels;
if (const_alpha != 256) {
if (const_alpha != 0) {
const __m128i nullVector = _mm_set1_epi32(0);
const __m128i half = _mm_set1_epi16(0x80);
const __m128i colorMask = _mm_set1_epi32(0x00ff00ff);
@ -119,12 +118,10 @@ void qt_blend_rgb32_on_rgb32_sse2(uchar *destPixels, int dbpl,
for (; x < w-3; x += 4) {
__m128i srcVector = _mm_loadu_si128((const __m128i *)&src[x]);
if (_mm_movemask_epi8(_mm_cmpeq_epi32(srcVector, nullVector)) != 0xffff) {
const __m128i dstVector = _mm_load_si128((__m128i *)&dst[x]);
__m128i result;
INTERPOLATE_PIXEL_255_SSE2(result, srcVector, dstVector, constAlphaVector, oneMinusConstAlpha, colorMask, half);
_mm_store_si128((__m128i *)&dst[x], result);
}
const __m128i dstVector = _mm_load_si128((__m128i *)&dst[x]);
__m128i result;
INTERPOLATE_PIXEL_255_SSE2(result, srcVector, dstVector, constAlphaVector, oneMinusConstAlpha, colorMask, half);
_mm_store_si128((__m128i *)&dst[x], result);
}
SIMD_EPILOGUE(x, w, 3)
dst[x] = INTERPOLATE_PIXEL_255(src[x], const_alpha, dst[x], one_minus_const_alpha);

20
tests/auto/gui/painting/qpainter/tst_qpainter.cpp
View File

@ -300,6 +300,8 @@ private slots:
void QTBUG56252();
void blendNullRGB32();
private:
void fillData();
void setPenColor(QPainter& p);
@ -5139,6 +5141,24 @@ void tst_QPainter::QTBUG56252()
// If no crash or illegal memory read, all is fine
}
void tst_QPainter::blendNullRGB32()
{
quint32 data[16] = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
QImage nullImage((const uchar*)data, 16, 1, QImage::Format_RGB32);
QImage image(16, 1, QImage::Format_RGB32);
image.fill(Qt::white);
QPainter paint(&image);
paint.setCompositionMode(QPainter::CompositionMode_Source);
paint.setOpacity(0.5);
paint.drawImage(0, 0, nullImage);
paint.end();
for (int i=0; i < image.width(); ++i)
QVERIFY(image.pixel(i,0) != 0xffffffff);
}
QTEST_MAIN(tst_QPainter)
#include "tst_qpainter.moc"