add ways to peer into an image to get its pixels

src/image/SkImage_Raster.cpp

Index: src/image/SkImage_Raster.cpp
diff --git a/src/image/SkImage_Raster.cpp b/src/image/SkImage_Raster.cpp
index ab8a635c1c9af4c0be6dc0bc2303739413226972..262fb97bfa7f3d1cac1f390a4ff7649842d9d8db 100644
--- a/src/image/SkImage_Raster.cpp
+++ b/src/image/SkImage_Raster.cpp
@@ -55,6 +55,8 @@ public:
 
     virtual void onDraw(SkCanvas*, SkScalar, SkScalar, const SkPaint*) SK_OVERRIDE;
     virtual void onDrawRectToRect(SkCanvas*, const SkRect*, const SkRect&, const SkPaint*) SK_OVERRIDE;
+    virtual bool onReadPixels(SkBitmap*, const SkIRect&) const SK_OVERRIDE;
+    virtual const void* onPeekPixels(SkImageInfo*, size_t* /*rowBytes*/) const SK_OVERRIDE;
     virtual bool getROPixels(SkBitmap*) const SK_OVERRIDE;
 
     // exposed for SkSurface_Raster via SkNewImageFromPixelRef
@@ -82,13 +84,20 @@ SkImage* SkImage_Raster::NewEmpty() {
     return gEmpty;
 }
 
+static void release_data(void* addr, void* context) {
+    SkData* data = static_cast<SkData*>(context);
+    data->unref();
+}
+
 SkImage_Raster::SkImage_Raster(const Info& info, SkData* data, size_t rowBytes)
-        : INHERITED(info.fWidth, info.fHeight) {
-    fBitmap.setConfig(info, rowBytes);
-    SkAutoTUnref<SkPixelRef> ref(
-        SkMallocPixelRef::NewWithData(info, rowBytes, NULL, data, 0));
-    fBitmap.setPixelRef(ref);
+    : INHERITED(info.fWidth, info.fHeight)
+{
+    data->ref();
+    void* addr = const_cast<void*>(data->data());
+
+    fBitmap.installPixels(info, addr, rowBytes, release_data, data);
     fBitmap.setImmutable();
+    fBitmap.lockPixels();
 }
 
 SkImage_Raster::SkImage_Raster(const Info& info, SkPixelRef* pr, size_t rowBytes)
@@ -96,6 +105,7 @@ SkImage_Raster::SkImage_Raster(const Info& info, SkPixelRef* pr, size_t rowBytes
 {
     fBitmap.setConfig(info, rowBytes);
     fBitmap.setPixelRef(pr);
+    fBitmap.lockPixels();
 }
 
 SkImage_Raster::~SkImage_Raster() {}
@@ -104,10 +114,34 @@ void SkImage_Raster::onDraw(SkCanvas* canvas, SkScalar x, SkScalar y, const SkPa
     canvas->drawBitmap(fBitmap, x, y, paint);
 }
 
-void SkImage_Raster::onDrawRectToRect(SkCanvas* canvas, const SkRect* src, const SkRect& dst, const SkPaint* paint) {
+void SkImage_Raster::onDrawRectToRect(SkCanvas* canvas, const SkRect* src,
+                                      const SkRect& dst, const SkPaint* paint) {
     canvas->drawBitmapRectToRect(fBitmap, src, dst, paint);
 }
 
+bool SkImage_Raster::onReadPixels(SkBitmap* dst, const SkIRect& subset) const {
+    if (dst->pixelRef()) {
+        return this->INHERITED::onReadPixels(dst, subset);
+    } else {
+        SkBitmap src;
+        if (!fBitmap.extractSubset(&src, subset)) {
+            return false;
+        }
+        return src.copyTo(dst, src.config());
+    }
+}
+
+const void* SkImage_Raster::onPeekPixels(SkImageInfo* infoPtr,
+                                         size_t* rowBytesPtr) const {
+    SkImageInfo info;
+    if (!fBitmap.asImageInfo(&info) || !fBitmap.getPixels()) {
+        return false;
+    }
+    *infoPtr = info;
+    *rowBytesPtr = fBitmap.rowBytes();
+    return fBitmap.getPixels();
+}
+
 bool SkImage_Raster::getROPixels(SkBitmap* dst) const {
     *dst = fBitmap;
     return true;