[PDF] Add unpremultiply support and a GM (try5)
This is a resubmit of https://codereview.chromium.org/22831039 which was
reverted because it causes issues on Windows.
BUG=chromium:175548
R=edisonn@google.com
Review URL: https://codereview.chromium.org/37873003
git-svn-id: http://skia.googlecode.com/svn/trunk@11945 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/gm/bitmappremul.cpp b/gm/bitmappremul.cpp
new file mode 100644
index 0000000..8b4c2d6
--- /dev/null
+++ b/gm/bitmappremul.cpp
@@ -0,0 +1,133 @@
+/*
+ * Copyright 2013 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "gm.h"
+#include "SkBitmap.h"
+#include "SkCanvas.h"
+#include "SkColorPriv.h"
+
+/**
+ * This GM checks that bitmap pixels are unpremultiplied before being exported
+ * to other formats. If unpremultiplication is implemented properly, this
+ * GM should come out completely white. If not, this GM looks like a row of two
+ * greyscale gradients above a row of grey lines.
+ * This tests both the ARGB4444 and ARGB8888 bitmap configurations.
+ */
+
+static const int SLIDE_SIZE = 256;
+static const int PIXEL_SIZE_8888 = SLIDE_SIZE / 256;
+static const int PIXEL_SIZE_4444 = SLIDE_SIZE / 16;
+
+static void init_bitmap(SkBitmap::Config config, SkBitmap* bitmap) {
+ bitmap->setConfig(config, SLIDE_SIZE, SLIDE_SIZE);
+ bitmap->allocPixels();
+ bitmap->eraseColor(SK_ColorWHITE);
+}
+
+static SkBitmap make_argb8888_gradient() {
+ SkBitmap bitmap;
+ init_bitmap(SkBitmap::kARGB_8888_Config, &bitmap);
+ uint8_t rowColor = 0;
+ for (int y = 0; y < SLIDE_SIZE; y++) {
+ uint32_t* dst = bitmap.getAddr32(0, y);
+ for (int x = 0; x < SLIDE_SIZE; x++) {
+ dst[x] = SkPackARGB32(rowColor, rowColor,
+ rowColor, rowColor);
+ }
+ if (y % PIXEL_SIZE_8888 == PIXEL_SIZE_8888 - 1) {
+ rowColor++;
+ }
+ }
+ return bitmap;
+}
+
+static SkBitmap make_argb4444_gradient() {
+ SkBitmap bitmap;
+ init_bitmap(SkBitmap::kARGB_4444_Config, &bitmap);
+ uint8_t rowColor = 0;
+ for (int y = 0; y < SLIDE_SIZE; y++) {
+ uint16_t* dst = bitmap.getAddr16(0, y);
+ for (int x = 0; x < SLIDE_SIZE; x++) {
+ dst[x] = SkPackARGB4444(rowColor, rowColor,
+ rowColor, rowColor);
+ }
+ if (y % PIXEL_SIZE_4444 == PIXEL_SIZE_4444 - 1) {
+ rowColor++;
+ }
+ }
+ return bitmap;
+}
+
+static SkBitmap make_argb8888_stripes() {
+ SkBitmap bitmap;
+ init_bitmap(SkBitmap::kARGB_8888_Config, &bitmap);
+ uint8_t rowColor = 0;
+ for (int y = 0; y < SLIDE_SIZE; y++) {
+ uint32_t* dst = bitmap.getAddr32(0, y);
+ for (int x = 0; x < SLIDE_SIZE; x++) {
+ dst[x] = SkPackARGB32(rowColor, rowColor,
+ rowColor, rowColor);
+ }
+ if (rowColor == 0) {
+ rowColor = 255;
+ } else {
+ rowColor = 0;
+ }
+ }
+ return bitmap;
+}
+
+static SkBitmap make_argb4444_stripes() {
+ SkBitmap bitmap;
+ init_bitmap(SkBitmap::kARGB_4444_Config, &bitmap);
+ uint8_t rowColor = 0;;
+ for (int y = 0; y < SLIDE_SIZE; y++) {
+ uint16_t* dst = bitmap.getAddr16(0, y);
+ for (int x = 0; x < SLIDE_SIZE; x++) {
+ dst[x] = SkPackARGB4444(rowColor, rowColor,
+ rowColor, rowColor);
+ }
+ if (rowColor == 0) {
+ rowColor = 15;
+ } else {
+ rowColor = 0;
+ }
+ }
+ return bitmap;
+}
+
+namespace skiagm {
+
+class BitmapPremulGM : public GM {
+public:
+ BitmapPremulGM() {
+ this->setBGColor(SK_ColorWHITE);
+ }
+
+protected:
+ SkString onShortName() SK_OVERRIDE {
+ return SkString("bitmap_premul");
+ }
+
+ virtual SkISize onISize() SK_OVERRIDE {
+ return SkISize::Make(SLIDE_SIZE * 2, SLIDE_SIZE * 2);
+ }
+
+ virtual void onDraw(SkCanvas* canvas) SK_OVERRIDE {
+ SkScalar slideSize = SkIntToScalar(SLIDE_SIZE);
+ canvas->drawBitmap(make_argb8888_gradient(), 0, 0);
+ canvas->drawBitmap(make_argb4444_gradient(), slideSize, 0);
+ canvas->drawBitmap(make_argb8888_stripes(), 0, slideSize);
+ canvas->drawBitmap(make_argb4444_stripes(), slideSize, slideSize);
+ }
+
+private:
+ typedef GM INHERITED;
+};
+
+DEF_GM( return new BitmapPremulGM; )
+}
diff --git a/gyp/gmslides.gypi b/gyp/gmslides.gypi
index a83ae2e..4591346 100644
--- a/gyp/gmslides.gypi
+++ b/gyp/gmslides.gypi
@@ -15,6 +15,7 @@
'../gm/bitmapcopy.cpp',
'../gm/bitmapmatrix.cpp',
'../gm/bitmapfilters.cpp',
+ '../gm/bitmappremul.cpp',
'../gm/bitmaprect.cpp',
'../gm/bitmaprecttest.cpp',
'../gm/bitmapscroll.cpp',
diff --git a/src/pdf/SkPDFImage.cpp b/src/pdf/SkPDFImage.cpp
index 19ad79e..ed20455 100644
--- a/src/pdf/SkPDFImage.cpp
+++ b/src/pdf/SkPDFImage.cpp
@@ -336,6 +336,157 @@
return result;
}
+/**
+ * Removes the alpha component of an ARGB color (including unpremultiply) while
+ * keeping the output in the same format as the input.
+ */
+static uint32_t remove_alpha_argb8888(uint32_t pmColor) {
+ SkColor color = SkUnPreMultiply::PMColorToColor(pmColor);
+ return SkPackARGB32NoCheck(SK_AlphaOPAQUE,
+ SkColorGetR(color),
+ SkColorGetG(color),
+ SkColorGetB(color));
+}
+
+static uint16_t remove_alpha_argb4444(uint16_t pmColor) {
+ return SkPixel32ToPixel4444(
+ remove_alpha_argb8888(SkPixel4444ToPixel32(pmColor)));
+}
+
+static uint32_t get_argb8888_neighbor_avg_color(const SkBitmap& bitmap,
+ int xOrig, int yOrig) {
+ uint8_t count = 0;
+ uint16_t r = 0;
+ uint16_t g = 0;
+ uint16_t b = 0;
+
+ for (int y = yOrig - 1; y <= yOrig + 1; y++) {
+ if (y < 0 || y >= bitmap.height()) {
+ continue;
+ }
+ uint32_t* src = bitmap.getAddr32(0, y);
+ for (int x = xOrig - 1; x <= xOrig + 1; x++) {
+ if (x < 0 || x >= bitmap.width()) {
+ continue;
+ }
+ if (SkGetPackedA32(src[x]) != SK_AlphaTRANSPARENT) {
+ uint32_t color = remove_alpha_argb8888(src[x]);
+ r += SkGetPackedR32(color);
+ g += SkGetPackedG32(color);
+ b += SkGetPackedB32(color);
+ count++;
+ }
+ }
+ }
+
+ if (count == 0) {
+ return SkPackARGB32NoCheck(SK_AlphaOPAQUE, 0, 0, 0);
+ } else {
+ return SkPackARGB32NoCheck(SK_AlphaOPAQUE,
+ r / count, g / count, b / count);
+ }
+}
+
+static uint16_t get_argb4444_neighbor_avg_color(const SkBitmap& bitmap,
+ int xOrig, int yOrig) {
+ uint8_t count = 0;
+ uint8_t r = 0;
+ uint8_t g = 0;
+ uint8_t b = 0;
+
+ for (int y = yOrig - 1; y <= yOrig + 1; y++) {
+ if (y < 0 || y >= bitmap.height()) {
+ continue;
+ }
+ uint16_t* src = bitmap.getAddr16(0, y);
+ for (int x = xOrig - 1; x <= xOrig + 1; x++) {
+ if (x < 0 || x >= bitmap.width()) {
+ continue;
+ }
+ if ((SkGetPackedA4444(src[x]) & 0x0F) != SK_AlphaTRANSPARENT) {
+ uint16_t color = remove_alpha_argb4444(src[x]);
+ r += SkGetPackedR4444(color);
+ g += SkGetPackedG4444(color);
+ b += SkGetPackedB4444(color);
+ count++;
+ }
+ }
+ }
+
+ if (count == 0) {
+ return SkPackARGB4444(SK_AlphaOPAQUE & 0x0F, 0, 0, 0);
+ } else {
+ return SkPackARGB4444(SK_AlphaOPAQUE & 0x0F,
+ r / count, g / count, b / count);
+ }
+}
+
+static SkBitmap unpremultiply_bitmap(const SkBitmap& bitmap,
+ const SkIRect& srcRect) {
+ SkBitmap outBitmap;
+ outBitmap.setConfig(bitmap.config(), srcRect.width(), srcRect.height());
+ outBitmap.allocPixels();
+ size_t dstRow = 0;
+
+ outBitmap.lockPixels();
+ bitmap.lockPixels();
+ switch (bitmap.config()) {
+ case SkBitmap::kARGB_4444_Config: {
+ for (int y = srcRect.fTop; y < srcRect.fBottom; y++) {
+ uint16_t* dst = outBitmap.getAddr16(0, dstRow);
+ uint16_t* src = bitmap.getAddr16(0, y);
+ for (int x = srcRect.fLeft; x < srcRect.fRight; x++) {
+ uint8_t a = SkGetPackedA4444(src[x]);
+ // It is necessary to average the color component of
+ // transparent pixels with their surrounding neighbors
+ // since the PDF renderer may separately re-sample the
+ // alpha and color channels when the image is not
+ // displayed at its native resolution. Since an alpha of
+ // zero gives no information about the color component,
+ // the pathological case is a white image with sharp
+ // transparency bounds - the color channel goes to black,
+ // and the should-be-transparent pixels are rendered
+ // as grey because of the separate soft mask and color
+ // resizing.
+ if (a == (SK_AlphaTRANSPARENT & 0x0F)) {
+ *dst = get_argb4444_neighbor_avg_color(bitmap, x, y);
+ } else {
+ *dst = remove_alpha_argb4444(src[x]);
+ }
+ dst++;
+ }
+ dstRow++;
+ }
+ break;
+ }
+ case SkBitmap::kARGB_8888_Config: {
+ for (int y = srcRect.fTop; y < srcRect.fBottom; y++) {
+ uint32_t* dst = outBitmap.getAddr32(0, dstRow);
+ uint32_t* src = bitmap.getAddr32(0, y);
+ for (int x = srcRect.fLeft; x < srcRect.fRight; x++) {
+ uint8_t a = SkGetPackedA32(src[x]);
+ if (a == SK_AlphaTRANSPARENT) {
+ *dst = get_argb8888_neighbor_avg_color(bitmap, x, y);
+ } else {
+ *dst = remove_alpha_argb8888(src[x]);
+ }
+ dst++;
+ }
+ dstRow++;
+ }
+ break;
+ }
+ default:
+ SkASSERT(false);
+ }
+ bitmap.unlockPixels();
+ outBitmap.unlockPixels();
+
+ outBitmap.setImmutable();
+
+ return outBitmap;
+}
+
// static
SkPDFImage* SkPDFImage::CreateImage(const SkBitmap& bitmap,
const SkIRect& srcRect,
@@ -358,8 +509,17 @@
return NULL;
}
- SkPDFImage* image = SkNEW_ARGS(SkPDFImage, (NULL, bitmap,
- false, srcRect, encoder));
+ SkPDFImage* image;
+ SkBitmap::Config config = bitmap.config();
+ if (alphaData.get() != NULL && (config == SkBitmap::kARGB_8888_Config ||
+ config == SkBitmap::kARGB_4444_Config)) {
+ SkBitmap unpremulBitmap = unpremultiply_bitmap(bitmap, srcRect);
+ image = SkNEW_ARGS(SkPDFImage, (NULL, unpremulBitmap, false,
+ SkIRect::MakeWH(srcRect.width(), srcRect.height()),
+ encoder));
+ } else {
+ image = SkNEW_ARGS(SkPDFImage, (NULL, bitmap, false, srcRect, encoder));
+ }
if (alphaData.get() != NULL) {
SkAutoTUnref<SkPDFImage> mask(
SkNEW_ARGS(SkPDFImage, (alphaData.get(), bitmap,