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Unified Diff: src/images/SkPNGImageEncoder.cpp

Issue 2325223002: Support RGBA/BGRA Premul/Unpremul from SkPNGImageEncoder (Closed)
Patch Set: Rebase Created 4 years, 3 months ago
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Index: src/images/SkPNGImageEncoder.cpp
diff --git a/src/images/SkPNGImageEncoder.cpp b/src/images/SkPNGImageEncoder.cpp
index a9c8b3d7857e2dd604fe9a531e3d676b04158c0e..b30cd2509a6b6aa0a856b1ea2e67f0e106e108fc 100644
--- a/src/images/SkPNGImageEncoder.cpp
+++ b/src/images/SkPNGImageEncoder.cpp
@@ -58,30 +58,30 @@ static void sk_write_fn(png_structp png_ptr, png_bytep data, png_size_t len) {
}
}
-static transform_scanline_proc choose_proc(SkColorType ct, bool hasAlpha) {
- // we don't care about search on alpha if we're kIndex8, since only the
- // colortable packing cares about that distinction, not the pixels
- if (kIndex_8_SkColorType == ct) {
- hasAlpha = false; // we store false in the table entries for kIndex8
- }
-
+static transform_scanline_proc choose_proc(SkColorType ct, SkAlphaType alphaType) {
static const struct {
SkColorType fColorType;
- bool fHasAlpha;
+ SkAlphaType fAlphaType;
transform_scanline_proc fProc;
} gMap[] = {
- { kRGB_565_SkColorType, false, transform_scanline_565 },
- { kN32_SkColorType, false, transform_scanline_888 },
- { kN32_SkColorType, true, transform_scanline_8888 },
- { kARGB_4444_SkColorType, false, transform_scanline_444 },
- { kARGB_4444_SkColorType, true, transform_scanline_4444 },
- { kIndex_8_SkColorType, false, transform_scanline_memcpy },
- { kGray_8_SkColorType, false, transform_scanline_memcpy },
+ { kRGB_565_SkColorType, kOpaque_SkAlphaType, transform_scanline_565 },
+ { kRGBA_8888_SkColorType, kOpaque_SkAlphaType, transform_scanline_RGBX },
+ { kBGRA_8888_SkColorType, kOpaque_SkAlphaType, transform_scanline_BGRX },
+ { kRGBA_8888_SkColorType, kPremul_SkAlphaType, transform_scanline_rgbA },
+ { kBGRA_8888_SkColorType, kPremul_SkAlphaType, transform_scanline_bgrA },
+ { kRGBA_8888_SkColorType, kUnpremul_SkAlphaType, transform_scanline_memcpy },
+ { kBGRA_8888_SkColorType, kUnpremul_SkAlphaType, transform_scanline_BGRA },
+ { kARGB_4444_SkColorType, kOpaque_SkAlphaType, transform_scanline_444 },
+ { kARGB_4444_SkColorType, kPremul_SkAlphaType, transform_scanline_4444 },
+ { kIndex_8_SkColorType, kOpaque_SkAlphaType, transform_scanline_memcpy },
+ { kIndex_8_SkColorType, kPremul_SkAlphaType, transform_scanline_memcpy },
+ { kIndex_8_SkColorType, kUnpremul_SkAlphaType, transform_scanline_memcpy },
+ { kGray_8_SkColorType, kOpaque_SkAlphaType, transform_scanline_memcpy },
};
- for (int i = SK_ARRAY_COUNT(gMap) - 1; i >= 0; --i) {
- if (gMap[i].fColorType == ct && gMap[i].fHasAlpha == hasAlpha) {
- return gMap[i].fProc;
+ for (auto entry : gMap) {
+ if (entry.fColorType == ct && entry.fAlphaType == alphaType) {
+ return entry.fProc;
}
}
sk_throw();
@@ -112,12 +112,12 @@ static int computeBitDepth(int colorCount) {
*/
static inline int pack_palette(SkColorTable* ctable,
png_color* SK_RESTRICT palette,
- png_byte* SK_RESTRICT trans, bool hasAlpha) {
+ png_byte* SK_RESTRICT trans, SkAlphaType alphaType) {
const SkPMColor* SK_RESTRICT colors = ctable ? ctable->readColors() : nullptr;
const int ctCount = ctable->count();
int i, num_trans = 0;
- if (hasAlpha) {
+ if (kOpaque_SkAlphaType != alphaType) {
/* first see if we have some number of fully opaque at the end of the
ctable. PNG allows num_trans < num_palette, but all of the trans
entries must come first in the palette. If I was smarter, I'd
@@ -134,18 +134,27 @@ static inline int pack_palette(SkColorTable* ctable,
num_trans -= 1;
}
- const SkUnPreMultiply::Scale* SK_RESTRICT table =
- SkUnPreMultiply::GetScaleTable();
-
- for (i = 0; i < num_trans; i++) {
- const SkPMColor c = *colors++;
- const unsigned a = SkGetPackedA32(c);
- const SkUnPreMultiply::Scale s = table[a];
- trans[i] = a;
- palette[i].red = SkUnPreMultiply::ApplyScale(s, SkGetPackedR32(c));
- palette[i].green = SkUnPreMultiply::ApplyScale(s,SkGetPackedG32(c));
- palette[i].blue = SkUnPreMultiply::ApplyScale(s, SkGetPackedB32(c));
+ if (kPremul_SkAlphaType == alphaType) {
+ const SkUnPreMultiply::Scale* SK_RESTRICT table = SkUnPreMultiply::GetScaleTable();
+ for (i = 0; i < num_trans; i++) {
+ const SkPMColor c = *colors++;
+ const unsigned a = SkGetPackedA32(c);
+ const SkUnPreMultiply::Scale s = table[a];
+ trans[i] = a;
+ palette[i].red = SkUnPreMultiply::ApplyScale(s, SkGetPackedR32(c));
+ palette[i].green = SkUnPreMultiply::ApplyScale(s,SkGetPackedG32(c));
+ palette[i].blue = SkUnPreMultiply::ApplyScale(s, SkGetPackedB32(c));
+ }
+ } else {
+ for (i = 0; i < num_trans; i++) {
+ const SkPMColor c = *colors++;
+ trans[i] = SkGetPackedA32(c);
+ palette[i].red = SkGetPackedR32(c);
+ palette[i].green = SkGetPackedG32(c);
+ palette[i].blue = SkGetPackedB32(c);
+ }
}
+
// now fall out of this if-block to use common code for the trailing
// opaque entries
}
@@ -165,7 +174,7 @@ protected:
bool onEncode(SkWStream* stream, const SkBitmap& bm, int quality) override;
private:
bool doEncode(SkWStream* stream, const SkBitmap& bm,
- const bool& hasAlpha, int colorType,
+ SkAlphaType alphaType, int colorType,
int bitDepth, SkColorType ct,
png_color_8& sig_bit);
@@ -180,12 +189,12 @@ bool SkPNGImageEncoder::onEncode(SkWStream* stream,
switch (originalBitmap.colorType()) {
case kIndex_8_SkColorType:
case kGray_8_SkColorType:
- case kN32_SkColorType:
+ case kRGBA_8888_SkColorType:
+ case kBGRA_8888_SkColorType:
case kARGB_4444_SkColorType:
case kRGB_565_SkColorType:
break;
default:
- // TODO(scroggo): support 8888-but-not-N32 natively.
// TODO(scroggo): support Alpha_8 as Grayscale(black)+Alpha
if (originalBitmap.copyTo(&copy, kN32_SkColorType)) {
bitmap = &copy;
@@ -193,7 +202,22 @@ bool SkPNGImageEncoder::onEncode(SkWStream* stream,
}
SkColorType ct = bitmap->colorType();
- const bool hasAlpha = !bitmap->isOpaque();
+ const SkAlphaType alphaType = bitmap->alphaType();
+ switch (alphaType) {
+ case kUnpremul_SkAlphaType:
+ if (kARGB_4444_SkColorType == ct) {
+ return false;
+ }
+
+ break;
+ case kOpaque_SkAlphaType:
+ case kPremul_SkAlphaType:
+ break;
+ default:
+ return false;
+ }
+
+ const bool isOpaque = (kOpaque_SkAlphaType == alphaType);
int bitDepth = 8; // default for color
png_color_8 sig_bit;
sk_bzero(&sig_bit, sizeof(png_color_8));
@@ -210,28 +234,29 @@ bool SkPNGImageEncoder::onEncode(SkWStream* stream,
case kGray_8_SkColorType:
sig_bit.gray = 8;
colorType = PNG_COLOR_TYPE_GRAY;
- SkASSERT(!hasAlpha);
+ SkASSERT(isOpaque);
break;
- case kN32_SkColorType:
+ case kRGBA_8888_SkColorType:
+ case kBGRA_8888_SkColorType:
sig_bit.red = 8;
sig_bit.green = 8;
sig_bit.blue = 8;
sig_bit.alpha = 8;
- colorType = hasAlpha ? PNG_COLOR_TYPE_RGB_ALPHA : PNG_COLOR_TYPE_RGB;
+ colorType = isOpaque ? PNG_COLOR_TYPE_RGB : PNG_COLOR_TYPE_RGB_ALPHA;
break;
case kARGB_4444_SkColorType:
sig_bit.red = 4;
sig_bit.green = 4;
sig_bit.blue = 4;
sig_bit.alpha = 4;
- colorType = hasAlpha ? PNG_COLOR_TYPE_RGB_ALPHA : PNG_COLOR_TYPE_RGB;
+ colorType = isOpaque ? PNG_COLOR_TYPE_RGB : PNG_COLOR_TYPE_RGB_ALPHA;
break;
case kRGB_565_SkColorType:
sig_bit.red = 5;
sig_bit.green = 6;
sig_bit.blue = 5;
colorType = PNG_COLOR_TYPE_RGB;
- SkASSERT(!hasAlpha);
+ SkASSERT(isOpaque);
break;
default:
return false;
@@ -253,11 +278,11 @@ bool SkPNGImageEncoder::onEncode(SkWStream* stream,
bitDepth = computeBitDepth(ctable->count());
}
- return doEncode(stream, *bitmap, hasAlpha, colorType, bitDepth, ct, sig_bit);
+ return doEncode(stream, *bitmap, alphaType, colorType, bitDepth, ct, sig_bit);
}
bool SkPNGImageEncoder::doEncode(SkWStream* stream, const SkBitmap& bitmap,
- const bool& hasAlpha, int colorType,
+ SkAlphaType alphaType, int colorType,
int bitDepth, SkColorType ct,
png_color_8& sig_bit) {
@@ -304,9 +329,9 @@ bool SkPNGImageEncoder::doEncode(SkWStream* stream, const SkBitmap& bitmap,
png_color paletteColors[256];
png_byte trans[256];
if (kIndex_8_SkColorType == ct) {
- SkColorTable* ct = bitmap.getColorTable();
- int numTrans = pack_palette(ct, paletteColors, trans, hasAlpha);
- png_set_PLTE(png_ptr, info_ptr, paletteColors, ct->count());
+ SkColorTable* colorTable = bitmap.getColorTable();
+ int numTrans = pack_palette(colorTable, paletteColors, trans, alphaType);
+ png_set_PLTE(png_ptr, info_ptr, paletteColors, colorTable->count());
if (numTrans > 0) {
png_set_tRNS(png_ptr, info_ptr, trans, numTrans, nullptr);
}
@@ -318,11 +343,11 @@ bool SkPNGImageEncoder::doEncode(SkWStream* stream, const SkBitmap& bitmap,
const char* srcImage = (const char*)bitmap.getPixels();
SkAutoSTMalloc<1024, char> rowStorage(bitmap.width() << 2);
char* storage = rowStorage.get();
- transform_scanline_proc proc = choose_proc(ct, hasAlpha);
+ transform_scanline_proc proc = choose_proc(ct, alphaType);
for (int y = 0; y < bitmap.height(); y++) {
png_bytep row_ptr = (png_bytep)storage;
- proc(srcImage, bitmap.width(), storage);
+ proc(storage, srcImage, bitmap.width(), SkColorTypeBytesPerPixel(ct));
png_write_rows(png_ptr, &row_ptr, 1);
srcImage += bitmap.rowBytes();
}
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