2 files changed, 68 insertions, 3 deletions

diff --git a/base/gfx/png_codec_unittest.cc b/base/gfx/png_codec_unittest.cc
index 9184abe..c9734a7 100644
--- a/base/gfx/png_codec_unittest.cc
+++ b/base/gfx/png_codec_unittest.cc
@@ -7,6 +7,7 @@
 #include "base/gfx/png_encoder.h"
 #include "base/gfx/png_decoder.h"
 #include "testing/gtest/include/gtest/gtest.h"
+#include "third_party/skia/include/core/SkBitmap.h"
 
 static void MakeRGBImage(int w, int h, std::vector<unsigned char>* dat) {
   dat->resize(w * h * 3);
@@ -41,6 +42,25 @@ static void MakeRGBAImage(int w, int h, bool use_transparency,
   }
 }
 
+// Returns true if each channel of the given two colors are "close." This is
+// used for comparing colors where rounding errors may cause off-by-one.
+bool ColorsClose(uint32_t a, uint32_t b) {
+  return abs(static_cast<int>(SkColorGetB(a) - SkColorGetB(b))) < 2 &&
+         abs(static_cast<int>(SkColorGetG(a) - SkColorGetG(b))) < 2 &&
+         abs(static_cast<int>(SkColorGetR(a) - SkColorGetR(b))) < 2 &&
+         abs(static_cast<int>(SkColorGetA(a) - SkColorGetA(b))) < 2;
+}
+
+void MakeTestSkBitmap(int w, int h, SkBitmap* bmp) {
+  bmp->setConfig(SkBitmap::kARGB_8888_Config, w, h);
+  bmp->allocPixels();
+
+  uint32_t* src_data = bmp->getAddr32(0, 0);
+  for (int i = 0; i < w * h; i++) {
+    src_data[i] = SkPreMultiplyARGB(i % 255, i % 250, i % 245, i % 240);
+  }
+}
+
 TEST(PNGCodec, EncodeDecodeRGB) {
   const int w = 20, h = 20;
 
@@ -200,3 +220,30 @@ TEST(PNGCodec, StripAddAlpha) {
   ASSERT_EQ(original_rgb.size(), decoded.size());
   ASSERT_TRUE(original_rgb == decoded);
 }
+
+TEST(PNGCodec, EncodeBGRASkBitmap) {
+  const int w = 20, h = 20;
+
+  SkBitmap original_bitmap;
+  MakeTestSkBitmap(w, h, &original_bitmap);
+
+  // Encode the bitmap.
+  std::vector<unsigned char> encoded;
+  PNGEncoder::EncodeBGRASkBitmap(original_bitmap, false, &encoded);
+
+  // Decode the encoded string.
+  SkBitmap decoded_bitmap;
+  EXPECT_TRUE(PNGDecoder::Decode(&encoded, &decoded_bitmap));
+
+  // Compare the original bitmap and the output bitmap. We use ColorsClose
+  // as SkBitmaps are considered to be pre-multiplied, the unpremultiplication
+  // (in Encode) and repremultiplication (in Decode) can be lossy.
+  for (int x = 0; x < w; x++) {
+    for (int y = 0; y < h; y++) {
+      uint32_t original_pixel = original_bitmap.getAddr32(0, y)[x];
+      uint32_t decoded_pixel = decoded_bitmap.getAddr32(0, y)[x];
+      EXPECT_TRUE(ColorsClose(original_pixel, decoded_pixel));
+    }
+  }
+}
+
diff --git a/base/gfx/png_decoder.cc b/base/gfx/png_decoder.cc
index e493464..bd36c57 100644
--- a/base/gfx/png_decoder.cc
+++ b/base/gfx/png_decoder.cc
@@ -261,8 +261,8 @@ class PngReadStructDestroyer {
 
 // static
 bool PNGDecoder::Decode(const unsigned char* input, size_t input_size,
-                      ColorFormat format, std::vector<unsigned char>* output,
-                      int* w, int* h) {
+                        ColorFormat format, std::vector<unsigned char>* output,
+                        int* w, int* h) {
   if (input_size < 8)
     return false;  // Input data too small to be a png
 
@@ -324,7 +324,25 @@ bool PNGDecoder::Decode(const std::vector<unsigned char>* data,
                          &decoded_data, &width, &height)) {
     bitmap->setConfig(SkBitmap::kARGB_8888_Config, width, height);
     bitmap->allocPixels();
-    memcpy(bitmap->getPixels(), &decoded_data.front(), width * height * 4);
+    for (int y = 0; y < height; y++) {
+      for (int x = 0; x < width; x++) {
+        int pix = (y * height + x) * 4;
+        unsigned char alpha = decoded_data[pix + 3];
+        if (alpha != 0 && alpha != 255) {
+          bitmap->getAddr32(0, y)[x] = SkColorSetARGB(
+              alpha,
+              (decoded_data[pix + 2] * alpha) >> 8,
+              (decoded_data[pix + 1] * alpha) >> 8,
+              (decoded_data[pix] * alpha) >> 8);
+        } else {
+          bitmap->getAddr32(0, y)[x] = SkColorSetARGB(
+              alpha,
+              decoded_data[pix + 2],
+              decoded_data[pix + 1],
+              decoded_data[pix]);
+        }
+      }
+    }
     return true;
   }
   return false;