SkCodec: add wbmp class

dm/DMSrcSink.cpp

Index: dm/DMSrcSink.cpp
diff --git a/dm/DMSrcSink.cpp b/dm/DMSrcSink.cpp
index 5242c95e83a77f2caaf6047d3e67e41a2ed61a6c..b2e9a552cc66c8608634b931232c21dbbd3d68ee 100644
--- a/dm/DMSrcSink.cpp
+++ b/dm/DMSrcSink.cpp
@@ -93,7 +93,12 @@ Error CodecSrc::draw(SkCanvas* canvas) const {
                 case SkImageGenerator::kIncompleteInput:
                     break;
                 case SkImageGenerator::kInvalidConversion:
+                    bitmap.reset();
+                    if (SkInstallDiscardablePixelRef(codec.detach(), &bitmap)) {

[msarett, 2015/03/26 12:37:35]

What does this do?  I'm just not sure I understand.

[scroggo, 2015/03/26 14:37:57]

SkInstallDiscardablePixelRef is declared in SkImageGenerator.h. It lets us
lazily call onGetPixels at draw time. In order to support this, we need to make
sure all of our codecs support rewinding, and can draw to the type they report.

This means we'll need to rethink when we report Unpremul (which we still cannot
draw, and will be slower in raster once we do support it) or a colortype we
don't support.

I've been trying to figure out how we can support testing index8. We currently
choose the color type above based on the destination canvas. This is one sneaky
way, so long as the image doesn't support 8888 or 565. In gold it will not
report that the image was decoded to index8 though.

Another way would be to make a different decision about what the colorType
should be.

[hal.canary, 2015/03/26 17:10:53]

I am removing this code for now.

+                        break;
+                    }
                     return Error::Nonfatal("Incompatible colortype conversion");
+
                 default:
                     // Everything else is considered a failure.
                     return SkStringPrintf("Couldn't getPixels %s.", fPath.c_str());