Unpremultiply SkBitmaps for PDF output
BUG=skia:236, chromium:175548 R=vandebo@chromium.org, edisonn@google.com, reed@google.com Author: richardlin@chromium.org Review URL: https://chromiumcodereview.appspot.com/22329003 git-svn-id: http://skia.googlecode.com/svn/trunk@10725 2bbb7eff-a529-9590-31e7-b0007b416f81
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gm/bitmappremul.cpp
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131
gm/bitmappremul.cpp
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/*
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* Copyright 2013 Google Inc.
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*
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* Use of this source code is governed by a BSD-style license that can be
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* found in the LICENSE file.
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*/
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#include "gm.h"
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#include "SkBitmap.h"
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#include "SkCanvas.h"
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#include "SkColorPriv.h"
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/**
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* This GM checks that bitmap pixels are unpremultiplied before being exported
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* to other formats. If unpremultiplication is implemented properly, this
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* GM should come out completely white. If not, this GM looks like a row of two
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* greyscale gradients above a row of grey lines.
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* This tests both the ARGB4444 and ARGB8888 bitmap configurations.
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*/
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static const int SLIDE_SIZE = 256;
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static const int PIXEL_SIZE_8888 = SLIDE_SIZE / 256;
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static const int PIXEL_SIZE_4444 = SLIDE_SIZE / 16;
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static SkBitmap init_bitmap(SkBitmap::Config config) {
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SkBitmap bitmap;
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bitmap.setConfig(config, SLIDE_SIZE, SLIDE_SIZE);
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bitmap.allocPixels();
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bitmap.eraseColor(SK_ColorWHITE);
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return bitmap;
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}
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static SkBitmap make_argb8888_gradient() {
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SkBitmap bitmap = init_bitmap(SkBitmap::kARGB_8888_Config);
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uint8_t rowColor = 0;
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for (int y = 0; y < SLIDE_SIZE; y++) {
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uint32_t* dst = bitmap.getAddr32(0, y);
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for (int x = 0; x < SLIDE_SIZE; x++) {
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dst[x] = SkPackARGB32(rowColor, rowColor,
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rowColor, rowColor);
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}
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if (y % PIXEL_SIZE_8888 == PIXEL_SIZE_8888 - 1) {
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rowColor++;
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}
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}
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return bitmap;
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}
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static SkBitmap make_argb4444_gradient() {
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SkBitmap bitmap = init_bitmap(SkBitmap::kARGB_4444_Config);
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uint8_t rowColor = 0;
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for (int y = 0; y < SLIDE_SIZE; y++) {
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uint16_t* dst = bitmap.getAddr16(0, y);
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for (int x = 0; x < SLIDE_SIZE; x++) {
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dst[x] = SkPackARGB4444(rowColor, rowColor,
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rowColor, rowColor);
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}
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if (y % PIXEL_SIZE_4444 == PIXEL_SIZE_4444 - 1) {
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rowColor++;
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}
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}
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return bitmap;
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}
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static SkBitmap make_argb8888_stripes() {
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SkBitmap bitmap = init_bitmap(SkBitmap::kARGB_8888_Config);
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uint8_t rowColor = 0;
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for (int y = 0; y < SLIDE_SIZE; y++) {
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uint32_t* dst = bitmap.getAddr32(0, y);
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for (int x = 0; x < SLIDE_SIZE; x++) {
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dst[x] = SkPackARGB32(rowColor, rowColor,
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rowColor, rowColor);
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}
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if (rowColor == 0) {
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rowColor = 255;
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} else {
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rowColor = 0;
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}
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}
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return bitmap;
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}
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static SkBitmap make_argb4444_stripes() {
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SkBitmap bitmap = init_bitmap(SkBitmap::kARGB_4444_Config);
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uint8_t rowColor = 0;;
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for (int y = 0; y < SLIDE_SIZE; y++) {
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uint16_t* dst = bitmap.getAddr16(0, y);
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for (int x = 0; x < SLIDE_SIZE; x++) {
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dst[x] = SkPackARGB4444(rowColor, rowColor,
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rowColor, rowColor);
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}
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if (rowColor == 0) {
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rowColor = 15;
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} else {
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rowColor = 0;
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}
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}
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return bitmap;
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}
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namespace skiagm {
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class BitmapPremulGM : public GM {
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public:
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BitmapPremulGM() {
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this->setBGColor(0xFFFFFFFF);
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}
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protected:
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SkString onShortName() SK_OVERRIDE {
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return SkString("bitmap_premul");
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}
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virtual SkISize onISize() SK_OVERRIDE {
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return SkISize::Make(512, 512);
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}
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virtual void onDraw(SkCanvas* canvas) SK_OVERRIDE {
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SkScalar slideSize = SLIDE_SIZE;
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canvas->drawBitmap(make_argb8888_gradient(), 0, 0);
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canvas->drawBitmap(make_argb4444_gradient(), slideSize, 0);
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canvas->drawBitmap(make_argb8888_stripes(), 0, slideSize);
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canvas->drawBitmap(make_argb4444_stripes(), slideSize, slideSize);
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}
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private:
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typedef GM INHERITED;
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};
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DEF_GM( return new BitmapPremulGM; )
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}
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@ -12,6 +12,7 @@
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'../gm/bitmapcopy.cpp',
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'../gm/bitmapmatrix.cpp',
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'../gm/bitmapfilters.cpp',
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'../gm/bitmappremul.cpp',
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'../gm/bitmaprect.cpp',
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'../gm/bitmaprecttest.cpp',
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'../gm/bitmapscroll.cpp',
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@ -18,6 +18,57 @@
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namespace {
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static void unpremultiply_and_pack_argb8888(uint32_t src, uint8_t dst[3]) {
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uint8_t alpha = SkGetPackedA32(src);
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if (alpha != SK_AlphaOPAQUE) {
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SkColor unpremul = SkUnPreMultiply::PMColorToColor(src);
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dst[0] = SkColorGetR(unpremul);
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dst[1] = SkColorGetG(unpremul);
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dst[2] = SkColorGetB(unpremul);
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} else {
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dst[0] = SkGetPackedR32(src);
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dst[1] = SkGetPackedG32(src);
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dst[2] = SkGetPackedB32(src);
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}
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}
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static void unpremultiply_and_pack_argb4444(uint16_t src0, uint16_t src1,
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uint8_t dst[3]) {
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// Unpack and transform the alpha values from 4 bits to 8 bits.
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// This is necessary since the unpremultiply functions expect to work in
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// 8-bit space, but we are passing in 4-bit values. Since we scale up
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// the alpha, we scale down the amount the value is increased by, so that
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// the results are correct for 4-bit color components.
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uint8_t alpha0 = SkGetPackedA4444(src0);
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alpha0 = alpha0 | (alpha0 << 4);
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if (alpha0 != SK_AlphaOPAQUE) {
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SkUnPreMultiply::Scale scale0 = SkUnPreMultiply::GetScale(alpha0);
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dst[0] = SkUnPreMultiply::ApplyScale(scale0,
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SkGetPackedR4444(src0)) << 4;
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dst[0] |= SkUnPreMultiply::ApplyScale(scale0, SkGetPackedG4444(src0));
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dst[1] = SkUnPreMultiply::ApplyScale(scale0,
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SkGetPackedB4444(src0)) << 4;
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} else {
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dst[0] = SkGetPackedR4444(src0) << 4;
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dst[0] |= SkGetPackedG4444(src0);
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dst[1] = SkGetPackedB4444(src0) << 4;
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}
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uint8_t alpha1 = SkGetPackedA4444(src1);
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alpha1 = alpha1 | (alpha1 << 4);
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if (alpha1 != SK_AlphaOPAQUE) {
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SkUnPreMultiply::Scale scale1 = SkUnPreMultiply::GetScale(alpha1);
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dst[1] |= SkUnPreMultiply::ApplyScale(scale1, SkGetPackedR4444(src1));
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dst[2] = SkUnPreMultiply::ApplyScale(scale1,
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SkGetPackedG4444(src1)) << 4;
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dst[2] |= SkUnPreMultiply::ApplyScale(scale1, SkGetPackedB4444(src1));
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} else {
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dst[1] |= SkGetPackedR4444(src1);
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dst[2] = SkGetPackedG4444(src1) << 4;
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dst[2] |= SkGetPackedB4444(src1);
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}
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}
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void extractImageData(const SkBitmap& bitmap, const SkIRect& srcRect,
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SkStream** imageData, SkStream** alphaData) {
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SkMemoryStream* image = NULL;
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@ -49,36 +100,35 @@ void extractImageData(const SkBitmap& bitmap, const SkIRect& srcRect,
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uint16_t* src = bitmap.getAddr16(0, y);
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int x;
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for (x = srcRect.fLeft; x + 1 < srcRect.fRight; x += 2) {
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dst[0] = (SkGetPackedR4444(src[x]) << 4) |
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SkGetPackedG4444(src[x]);
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dst[1] = (SkGetPackedB4444(src[x]) << 4) |
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SkGetPackedR4444(src[x + 1]);
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dst[2] = (SkGetPackedG4444(src[x + 1]) << 4) |
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SkGetPackedB4444(src[x + 1]);
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dst += 3;
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alphaDst[0] = (SkGetPackedA4444(src[x]) << 4) |
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SkGetPackedA4444(src[x + 1]);
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if (alphaDst[0] != 0xFF) {
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SkGetPackedA4444(src[x + 1]);
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if (alphaDst[0] != SK_AlphaOPAQUE) {
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hasAlpha = true;
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}
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if (alphaDst[0]) {
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isTransparent = false;
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}
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unpremultiply_and_pack_argb4444(src[x], src[x + 1], dst);
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alphaDst++;
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dst += 3;
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}
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if (srcRect.width() & 1) {
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dst[0] = (SkGetPackedR4444(src[x]) << 4) |
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SkGetPackedG4444(src[x]);
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dst[1] = (SkGetPackedB4444(src[x]) << 4);
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dst += 2;
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alphaDst[0] = (SkGetPackedA4444(src[x]) << 4);
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alphaDst[0] = SkGetPackedA4444(src[x]) << 4;
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// Use a buffer to translate from the usual 2 4444 values
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// in 3 bytes to the single 4444 value in 2 bytes.
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uint8_t buffer[3];
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if (alphaDst[0] != 0xF0) {
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hasAlpha = true;
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}
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if (alphaDst[0] & 0xF0) {
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isTransparent = false;
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}
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unpremultiply_and_pack_argb4444(src[x], 0x00, buffer);
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dst[0] = buffer[0];
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dst[1] = buffer[1];
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alphaDst++;
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dst += 2;
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}
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}
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break;
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@ -108,18 +158,16 @@ void extractImageData(const SkBitmap& bitmap, const SkIRect& srcRect,
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for (int y = srcRect.fTop; y < srcRect.fBottom; y++) {
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uint32_t* src = bitmap.getAddr32(0, y);
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for (int x = srcRect.fLeft; x < srcRect.fRight; x++) {
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dst[0] = SkGetPackedR32(src[x]);
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dst[1] = SkGetPackedG32(src[x]);
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dst[2] = SkGetPackedB32(src[x]);
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dst += 3;
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alphaDst[0] = SkGetPackedA32(src[x]);
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if (alphaDst[0] != 0xFF) {
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if (alphaDst[0] != SK_AlphaOPAQUE) {
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hasAlpha = true;
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}
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if (alphaDst[0]) {
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if (alphaDst[0] != SK_AlphaTRANSPARENT) {
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isTransparent = false;
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}
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unpremultiply_and_pack_argb8888(src[x], dst);
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alphaDst++;
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dst += 3;
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}
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}
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break;
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