change old picture serialization to really handle images

src/lazy/SkDiscardablePixelRef.cpp

Index: src/lazy/SkDiscardablePixelRef.cpp
diff --git a/src/lazy/SkDiscardablePixelRef.cpp b/src/lazy/SkDiscardablePixelRef.cpp
index 1e42042fb6d10c05626f8a3d5bedd28dfcb257c8..0d34b63e1d592084669b2d18bef6c32bc4286d8e 100644
--- a/src/lazy/SkDiscardablePixelRef.cpp
+++ b/src/lazy/SkDiscardablePixelRef.cpp
@@ -107,19 +107,31 @@ void SkDiscardablePixelRef::onUnlockPixels() {
     fDiscardableMemoryIsLocked = false;
 }
 
-bool SkInstallDiscardablePixelRef(SkImageGenerator* generator, SkBitmap* dst,
+bool SkInstallDiscardablePixelRef(SkImageGenerator* generator, const SkIRect* subset, SkBitmap* dst,
                                   SkDiscardableMemory::Factory* factory) {
     SkAutoTDelete<SkImageGenerator> autoGenerator(generator);
     if (NULL == autoGenerator.get()) {
         return false;
     }
+
+    SkIPoint origin = SkIPoint::Make(0, 0);
     SkImageInfo info = autoGenerator->getInfo();
-    if (info.isEmpty() || !dst->setInfo(info)) {
+    if (info.isEmpty()) {
+        return false;
+    }
+    if (subset) {
+        if (subset->isEmpty() || !SkIRect::MakeWH(info.width(), info.height()).contains(*subset)) {
+            return false;
+        }
+        info = info.makeWH(subset->width(), subset->height());
+        origin.set(subset->x(), subset->y());
+    }
+    if (!dst->setInfo(info)) {
         return false;
     }
+
     // Since dst->setInfo() may have changed/fixed-up info, we copy it back from that bitmap
     info = dst->info();
-
     SkASSERT(info.colorType() != kUnknown_SkColorType);
     if (dst->empty()) {  // Use a normal pixelref.
         return dst->tryAllocPixels();
@@ -127,17 +139,17 @@ bool SkInstallDiscardablePixelRef(SkImageGenerator* generator, SkBitmap* dst,
     SkAutoTUnref<SkDiscardablePixelRef> ref(
         SkNEW_ARGS(SkDiscardablePixelRef,
                    (info, autoGenerator.detach(), dst->rowBytes(), factory)));
-    dst->setPixelRef(ref);
+    dst->setPixelRef(ref, origin.x(), origin.y());
     return true;
 }
 
 // These are the public API
 
 bool SkInstallDiscardablePixelRef(SkImageGenerator* generator, SkBitmap* dst) {
-    return SkInstallDiscardablePixelRef(generator, dst, NULL);
+    return SkInstallDiscardablePixelRef(generator, NULL, dst, NULL);
 }
 
 bool SkInstallDiscardablePixelRef(SkData* encoded, SkBitmap* dst) {
     SkImageGenerator* generator = SkImageGenerator::NewFromData(encoded);
-    return generator ? SkInstallDiscardablePixelRef(generator, dst, NULL) : false;
+    return generator ? SkInstallDiscardablePixelRef(generator, NULL, dst, NULL) : false;
 }