Fix for Issue 331895: Make gesturenav screenshot greyscale

ui/gfx/codec/png_codec_unittest.cc

Index: ui/gfx/codec/png_codec_unittest.cc
diff --git a/ui/gfx/codec/png_codec_unittest.cc b/ui/gfx/codec/png_codec_unittest.cc
index f1654d9d363bfbf15a5594c6ea3cfa9b66067a2e..f332173d6f9458ce37cd944adc039e6bab7c3c32 100644
--- a/ui/gfx/codec/png_codec_unittest.cc
+++ b/ui/gfx/codec/png_codec_unittest.cc
@@ -249,7 +249,15 @@ bool NonAlphaColorsClose(uint32_t a, uint32_t b) {
          abs(static_cast<int>(SkColorGetR(a) - SkColorGetR(b))) < 2;
 }
 
-void MakeTestSkBitmap(int w, int h, SkBitmap* bmp) {
+// Returns true if the BGRA 4-bit SkColor is "close" to the Gray 8-bit SkColor.

[Peter Kasting, 2014/02/04 01:37:15]

Nit: Don't you mean 32-bit (or 4-byte)?

+bool BGRAGrayColorsClose(uint32_t a, uint8_t b) {
+  return abs(static_cast<int>(SkColorGetB(a) - b)) < 2 &&
+         abs(static_cast<int>(SkColorGetG(a) - b)) < 2 &&
+         abs(static_cast<int>(SkColorGetR(a) - b)) < 2 &&
+         abs(static_cast<int>(SkColorGetA(a) - 255)) < 2;
+}
+
+void MakeTestBGRASkBitmap(int w, int h, SkBitmap* bmp) {
   bmp->setConfig(SkBitmap::kARGB_8888_Config, w, h);
   bmp->allocPixels();
 
@@ -259,6 +267,16 @@ void MakeTestSkBitmap(int w, int h, SkBitmap* bmp) {
   }
 }
 
+void MakeTestA8SkBitmap(int w, int h, SkBitmap* bmp) {
+  bmp->setConfig(SkBitmap::kA8_Config, w, h);
+  bmp->allocPixels();
+
+  uint8_t* src_data = bmp->getAddr8(0, 0);
+  for (int i = 0; i < w * h; i++) {

[Peter Kasting, 2014/02/04 01:37:15]

Nit: {} unnecessary

+    src_data[i] = i % 255;
+  }
+}
+
 TEST(PNGCodec, EncodeDecodeRGB) {
   const int w = 20, h = 20;
 
@@ -1017,7 +1035,7 @@ TEST(PNGCodec, EncodeBGRASkBitmap) {
   const int w = 20, h = 20;
 
   SkBitmap original_bitmap;
-  MakeTestSkBitmap(w, h, &original_bitmap);
+  MakeTestBGRASkBitmap(w, h, &original_bitmap);
 
   // Encode the bitmap.
   std::vector<unsigned char> encoded;
@@ -1040,11 +1058,35 @@ TEST(PNGCodec, EncodeBGRASkBitmap) {
   }
 }
 
+TEST(PNGCodec, EncodeA8SkBitmap) {
+  const int w = 20, h = 20;
+
+  SkBitmap original_bitmap;
+  MakeTestA8SkBitmap(w, h, &original_bitmap);
+
+  // Encode the bitmap.
+  std::vector<unsigned char> encoded;
+  EXPECT_TRUE(PNGCodec::EncodeA8SkBitmap(original_bitmap, &encoded));
+
+  // Decode the encoded string.
+  SkBitmap decoded_bitmap;
+  EXPECT_TRUE(PNGCodec::Decode(&encoded.front(), encoded.size(),
+                               &decoded_bitmap));
+
+  for (int x = 0; x < w; x++) {
+    for (int y = 0; y < h; y++) {
+      uint8_t original_pixel = *original_bitmap.getAddr8(x, y);
+      uint32_t decoded_pixel = *decoded_bitmap.getAddr32(x, y);
+      EXPECT_TRUE(BGRAGrayColorsClose(decoded_pixel, original_pixel));

[Peter Kasting, 2014/02/04 01:37:15]

How come we can't just check for direct equality?  Shouldn't a lossless encode
of a greyscale image be perfectly representable in full color?

+    }
+  }
+}
+
 TEST(PNGCodec, EncodeBGRASkBitmapDiscardTransparency) {
   const int w = 20, h = 20;
 
   SkBitmap original_bitmap;
-  MakeTestSkBitmap(w, h, &original_bitmap);
+  MakeTestBGRASkBitmap(w, h, &original_bitmap);
 
   // Encode the bitmap.
   std::vector<unsigned char> encoded;
@@ -1121,7 +1163,7 @@ TEST(PNGCodec, EncodeDecodeWithVaryingCompressionLevels) {
   // create an image with known values, a must be opaque because it will be
   // lost during encoding
   SkBitmap original_bitmap;
-  MakeTestSkBitmap(w, h, &original_bitmap);
+  MakeTestBGRASkBitmap(w, h, &original_bitmap);
 
   // encode
   std::vector<unsigned char> encoded_normal;