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handle interlacing

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git-svn-id: http://skia.googlecode.com/svn/trunk@161 2bbb7eff-a529-9590-31e7-b0007b416f81
This commit is contained in:
reed@android.com 2009-04-28 15:27:07 +00:00
parent af459795e3
commit 862e91be02
1 changed files with 24 additions and 14 deletions
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38
src/images/SkImageDecoder_libpng.cpp
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@ -387,15 +387,32 @@ bool SkPNGImageDecoder::onDecode(SkStream* sk_stream, SkBitmap* decodedBitmap,
} else {
sc = SkScaledBitmapSampler::kRGBX;
}
SkAutoMalloc storage(origWidth * srcBytesPerPixel);
if (!sampler.begin(decodedBitmap, sc, doDither)) {
return false;
}
const int height = decodedBitmap->height();
for (int i = 0; i < number_passes; i++) {
if (!sampler.begin(decodedBitmap, sc, doDither)) {
return false;
if (number_passes > 1) {
SkAutoMalloc storage(origWidth * origHeight * srcBytesPerPixel);
uint8_t* base = (uint8_t*)storage.get();
size_t rb = origWidth * srcBytesPerPixel;
for (int i = 0; i < number_passes; i++) {
uint8_t* row = base;
for (png_uint_32 y = 0; y < origHeight; y++) {
uint8_t* bmRow = row;
png_read_rows(png_ptr, &bmRow, png_bytepp_NULL, 1);
row += rb;
}
}
// now sample it
base += sampler.srcY0() * rb;
for (int y = 0; y < height; y++) {
reallyHasAlpha |= sampler.next(base);
base += sampler.srcDY() * rb;
}
} else {
SkAutoMalloc storage(origWidth * srcBytesPerPixel);
uint8_t* srcRow = (uint8_t*)storage.get();
skip_src_rows(png_ptr, srcRow, sampler.srcY0());
@ -407,20 +424,13 @@ bool SkPNGImageDecoder::onDecode(SkStream* sk_stream, SkBitmap* decodedBitmap,
skip_src_rows(png_ptr, srcRow, sampler.srcDY() - 1);
}
}
// skip the rest of the rows (if any)
png_uint_32 read = (height - 1) * sampler.srcDY() +
sampler.srcY0() + 1;
SkASSERT(read <= origHeight);
skip_src_rows(png_ptr, srcRow, origHeight - read);
}
if (hasAlpha && !reallyHasAlpha) {
#if 0
SkDEBUGF(("Image doesn't really have alpha [%d %d]\n",
origWidth, origHeight));
#endif
}
}
/* read rest of file, and get additional chunks in info_ptr - REQUIRED */