diff options
author | glen@chromium.org <glen@chromium.org@0039d316-1c4b-4281-b951-d872f2087c98> | 2009-06-04 02:44:33 +0000 |
---|---|---|
committer | glen@chromium.org <glen@chromium.org@0039d316-1c4b-4281-b951-d872f2087c98> | 2009-06-04 02:44:33 +0000 |
commit | 4b2fc165182614072ee2fa1c2130c7a5f484a125 (patch) | |
tree | c40a2c00f3c94881499bed1c67dd7aaa95ff30fa /base | |
parent | 47aef530fe0221533b954264831eebaa792764b6 (diff) | |
download | chromium_src-4b2fc165182614072ee2fa1c2130c7a5f484a125.zip chromium_src-4b2fc165182614072ee2fa1c2130c7a5f484a125.tar.gz chromium_src-4b2fc165182614072ee2fa1c2130c7a5f484a125.tar.bz2 |
PNGEncoder wasn't accounting for SkBitmap's premultiplied alpha (PNGDecoder was, however).
BUG=12891
Review URL: http://codereview.chromium.org/118106
git-svn-id: svn://svn.chromium.org/chrome/trunk/src@17590 0039d316-1c4b-4281-b951-d872f2087c98
Diffstat (limited to 'base')
-rw-r--r-- | base/gfx/png_encoder.cc | 37 |
1 files changed, 33 insertions, 4 deletions
diff --git a/base/gfx/png_encoder.cc b/base/gfx/png_encoder.cc index 5021721..d9e22db 100644 --- a/base/gfx/png_encoder.cc +++ b/base/gfx/png_encoder.cc @@ -5,6 +5,7 @@ #include "base/basictypes.h" #include "base/gfx/png_encoder.h" #include "base/logging.h" +#include "base/scoped_ptr.h" #include "third_party/skia/include/core/SkBitmap.h" extern "C" { @@ -197,9 +198,37 @@ bool PNGEncoder::Encode(const unsigned char* input, ColorFormat format, bool PNGEncoder::EncodeBGRASkBitmap(const SkBitmap& input, bool discard_transparency, std::vector<unsigned char>* output) { - SkAutoLockPixels input_lock(input); - DCHECK(input.empty() || input.bytesPerPixel() == 4); - return Encode(static_cast<unsigned char*>(input.getPixels()), - PNGEncoder::FORMAT_BGRA, input.width(), input.height(), + // This only works with images with four bytes per pixel. + static const int bbp = 4; + + DCHECK(input.empty() || input.bytesPerPixel() == bbp); + + // SkBitmaps are premultiplied, we need to unpremultiply them. + scoped_ptr<unsigned char> divided; + divided.reset(new unsigned char[input.width() * input.height() * bbp]); + + SkAutoLockPixels lock_input(input); + int i = 0; + for (int y = 0; y < input.height(); y++) { + uint32* src_row = input.getAddr32(0, y); + for (int x = 0; x < input.width(); x++) { + int alpha = SkColorGetA(src_row[x]); + if (alpha != 0 && alpha != 255) { + divided.get()[i + 0] = (SkColorGetR(src_row[x]) << 8) / alpha; + divided.get()[i + 1] = (SkColorGetG(src_row[x]) << 8) / alpha; + divided.get()[i + 2] = (SkColorGetB(src_row[x]) << 8) / alpha; + divided.get()[i + 3] = alpha; + } else { + divided.get()[i + 0] = SkColorGetR(src_row[x]); + divided.get()[i + 1] = SkColorGetG(src_row[x]); + divided.get()[i + 2] = SkColorGetB(src_row[x]); + divided.get()[i + 3] = SkColorGetA(src_row[x]); + } + i += bbp; + } + } + + return Encode(divided.release(), + PNGEncoder::FORMAT_RGBA, input.width(), input.height(), input.rowBytes(), discard_transparency, output); } |