Fix for Issue 331895: Make gesturenav screenshot greyscale

ui/gfx/codec/png_codec.cc

Index: ui/gfx/codec/png_codec.cc
diff --git a/ui/gfx/codec/png_codec.cc b/ui/gfx/codec/png_codec.cc
index b3f4345343f0d15a49c0cfc9c759bed662cc4189..201b7a6b8a6ade309df1cffe4a380800450636b7 100644
--- a/ui/gfx/codec/png_codec.cc
+++ b/ui/gfx/codec/png_codec.cc
@@ -678,15 +678,29 @@ bool EncodeWithCompressionLevel(const unsigned char* input,
       break;
 
     case PNGCodec::FORMAT_SkBitmap:
-      input_color_components = 4;
-      if (discard_transparency) {
-        output_color_components = 3;
-        png_output_color_type = PNG_COLOR_TYPE_RGB;
-        converter = ConvertSkiatoRGB;
+      // Compare row_byte_width and size.width() to detect the format of
+      // SkBitmap. kA8_Config (1bpp) and kARGB_8888_Config (4bpp) are the two
+      // supported formats

[Peter Kasting, 2014/01/25 03:29:58]

Nit: Trailing period

[mfomitchev, 2014/01/27 17:15:28]

Done.

+      if (row_byte_width < 4 * size.width()) {
+        // Not 4bpp, so must be 1bpp.
+        // Ignore discard_transparency - it doesn't make sense in this context,
+        // since alpha is the only thing we have and it needs to be used for
+        // color intensity.
+        input_color_components = 1;
+        output_color_components = 1;
+        png_output_color_type = PNG_COLOR_TYPE_GRAY;
+        //converter = NULL;

[Peter Kasting, 2014/01/25 03:29:58]

Nit: Remove this line.  If you need to explain that |converter| is explicitly
NULL, or say what that means, say that, otherwise just nuke it.

[mfomitchev, 2014/01/27 17:15:28]

Done.

       } else {
-        output_color_components = 4;
-        png_output_color_type = PNG_COLOR_TYPE_RGB_ALPHA;
-        converter = ConvertSkiatoRGBA;
+        input_color_components = 4;
+        if (discard_transparency) {
+          output_color_components = 3;
+          png_output_color_type = PNG_COLOR_TYPE_RGB;
+          converter = ConvertSkiatoRGB;
+        } else {
+          output_color_components = 4;
+          png_output_color_type = PNG_COLOR_TYPE_RGB_ALPHA;
+          converter = ConvertSkiatoRGBA;
+        }
       }
       break;
 
@@ -719,12 +733,36 @@ bool EncodeWithCompressionLevel(const unsigned char* input,
   return success;
 }
 
+bool InternalEncodeSkBitmap(const SkBitmap& input,
+                            int bpp,
+                            bool discard_transparency,
+                            int compression_level,
+                            std::vector<unsigned char>* output) {
+  if (input.empty())
+    return false;
+  DCHECK_EQ(input.bytesPerPixel(), bpp);

[Peter Kasting, 2014/01/25 03:29:58]

If these are always equal, why pass |bpp| at all?  We should just read it from
|input|.  This would also eliminate the need for the next DCHECK, since Skia
will guarantee that.

If you really want, you can DCHECK the BPP value on the caller side.

[mfomitchev, 2014/01/27 17:15:28]

Now EncodeA8SkBitmap() and EncodeBGRASkBitmap() are identical. Should  we just
replace them with one method EncodeSkBitmap() and clarify that only two formats
are supported in the comments? We'd can also rename FastEncodeBGRASkBitmap() to
FastEncodeSkBitmap().

[mfomitchev, 2014/01/27 17:15:28]

Now EncodeA8SkBitmap() and EncodeBGRASkBitmap() are identical. Should  we just
replace them with one method EncodeSkBitmap() and clarify that only two formats
are supported in the comments? We'd can also rename FastEncodeBGRASkBitmap() to
FastEncodeSkBitmap().

+  DCHECK_GE(static_cast<int>(input.rowBytes()), input.width() * bpp);
+
+  SkAutoLockPixels lock_input(input);
+  return EncodeWithCompressionLevel(
+      reinterpret_cast<unsigned char*>(input.getAddr32(0, 0)),
+      PNGCodec::FORMAT_SkBitmap,
+      Size(input.width(), input.height()),
+      static_cast<int>(input.rowBytes()),
+      discard_transparency,
+      std::vector<PNGCodec::Comment>(),
+      compression_level,
+      output);
+}
+
 
 }  // namespace
 
 // static
-bool PNGCodec::Encode(const unsigned char* input, ColorFormat format,
-                      const Size& size, int row_byte_width,
+bool PNGCodec::Encode(const unsigned char* input,
+                      ColorFormat format,
+                      const Size& size,
+                      int row_byte_width,
                       bool discard_transparency,
                       const std::vector<Comment>& comments,
                       std::vector<unsigned char>* output) {
@@ -742,37 +780,38 @@ bool PNGCodec::Encode(const unsigned char* input, ColorFormat format,
 bool PNGCodec::EncodeBGRASkBitmap(const SkBitmap& input,
                                   bool discard_transparency,
                                   std::vector<unsigned char>* output) {
-  static const int bbp = 4;
+  static const int bpp = 4;
 
-  if (input.empty())
-    return false;
-  DCHECK_EQ(input.bytesPerPixel(), bbp);
-  DCHECK_GE(static_cast<int>(input.rowBytes()), input.width() * bbp);
+  return InternalEncodeSkBitmap(input,
+                                bpp,
+                                discard_transparency,
+                                Z_DEFAULT_COMPRESSION,
+                                output);
+}
 
-  SkAutoLockPixels lock_input(input);
-  return Encode(reinterpret_cast<unsigned char*>(input.getAddr32(0, 0)),
-                FORMAT_SkBitmap, Size(input.width(), input.height()),
-                static_cast<int>(input.rowBytes()), discard_transparency,
-                std::vector<Comment>(), output);
+// static
+bool PNGCodec::EncodeA8SkBitmap(const SkBitmap& input,
+                                  std::vector<unsigned char>* output) {

[Peter Kasting, 2014/01/25 03:29:58]

Nit: Fix indenting

[mfomitchev, 2014/01/27 17:15:28]

Done.

+  static const int bpp = 1;
+
+  return InternalEncodeSkBitmap(input,
+                                bpp,
+                                false,
+                                Z_DEFAULT_COMPRESSION,
+                                output);
 }
 
 // static
 bool PNGCodec::FastEncodeBGRASkBitmap(const SkBitmap& input,
                                       bool discard_transparency,
                                       std::vector<unsigned char>* output) {
-  static const int bbp = 4;
+  static const int bpp = 4;
 
-  if (input.empty())
-    return false;
-  DCHECK_EQ(input.bytesPerPixel(), bbp);
-  DCHECK_GE(static_cast<int>(input.rowBytes()), input.width() * bbp);
-
-  SkAutoLockPixels lock_input(input);
-  return EncodeWithCompressionLevel(
-      reinterpret_cast<unsigned char*>(input.getAddr32(0, 0)),
-      FORMAT_SkBitmap, Size(input.width(), input.height()),
-      static_cast<int>(input.rowBytes()), discard_transparency,
-      std::vector<Comment>(), Z_BEST_SPEED, output);
+  return InternalEncodeSkBitmap(input,
+                                bpp,
+                                discard_transparency,
+                                Z_BEST_SPEED,
+                                output);
 }
 
 PNGCodec::Comment::Comment(const std::string& k, const std::string& t)