Proposal for SkImageGenerator::canDecodeAndScale API

src/core/SkImageGenerator.cpp

Index: src/core/SkImageGenerator.cpp
diff --git a/src/core/SkImageGenerator.cpp b/src/core/SkImageGenerator.cpp
index 187b46047af7e403feb2577940d15f0ea83a286f..0ce2cc9ed40d6c2a9d0c17cc3a2f1528060f652b 100644
--- a/src/core/SkImageGenerator.cpp
+++ b/src/core/SkImageGenerator.cpp
@@ -199,6 +199,26 @@ bool SkImageGenerator::tryGenerateBitmap(SkBitmap* bitmap, const SkImageInfo* in
     return true;
 }
 
+bool SkImageGenerator::canDecodeAndScale(const SkColorType colorType, const SkScalar scale, SkISize *availableSize, SkISize *lowerSize) {
+    return this->onCanDecodeAndScale(colorType, scale, availableSize, lowerSize);
+}
+
+bool SkImageGenerator::onCanDecodeAndScale(const SkColorType colorType, const SkScalar scale, SkISize *availableSize, SkISize *lowerSize) {
+    if (colorType != fInfo.colorType())
+        return false;
+    if (scale != SK_Scalar1)
+        return false;
+    if (availableSize) {
+        availableSize->fWidth = fInfo.width();
+        availableSize->fHeight = fInfo.height();
+    }
+    if (lowerSize) {
+        availableSize->fWidth = availableSize->fHeight = 0;
+    }
+    return true;
+}
+
+
 #include "SkGraphics.h"
 
 static SkGraphics::ImageGeneratorFromEncodedFactory gFactory;
@@ -217,8 +237,10 @@ SkImageGenerator* SkImageGenerator::NewFromEncoded(SkData* data) {
     }
     if (gFactory) {
         if (SkImageGenerator* generator = gFactory(data)) {
+            SkDebugf("minggle %s generator opaque %d size %d %d", __func__, generator->getInfo().isOpaque(), generator->getInfo().width(), generator->getInfo().height());
             return generator;
         }
     }
+    SkDebugf("minggle %s generator1", __func__);
     return SkImageGenerator::NewFromEncodedImpl(data);
 }