Make SkImageGenerator::getPixels() return an enum.

The new enum describes the nature of the failure. This is in
preparation for writing a replacement for SkImageDecoder, which will
use this interface.

Update the comments for getPixels() to specify what it means to pass
an SkImageInfo with a different size.

Make SkImageGenerator Noncopyable.

Leave onGetYUV8Planes alone, since we have separate discussions
regarding modifying that API.

Make callers of SkImageDecoder consistently handle kPartialSuccess.
Previously, some callers considered it a failure, and others considered
it a success.

BUG=skia:3257

Review URL: https://codereview.chromium.org/919693002

1 files changed, 9 insertions, 3 deletions

diff --git a/src/lazy/SkCachingPixelRef.cpp b/src/lazy/SkCachingPixelRef.cpp
index 5ab96562ec..570fc6fbd7 100644
--- a/src/lazy/SkCachingPixelRef.cpp
+++ b/src/lazy/SkCachingPixelRef.cpp
@@ -52,9 +52,15 @@ bool SkCachingPixelRef::onNewLockPixels(LockRec* rec) {
             fErrorInDecoding = true;
             return false;
         }
-        if (!fImageGenerator->getPixels(info, fLockedBitmap.getPixels(), fRowBytes)) {
-            fErrorInDecoding = true;
-            return false;
+        const SkImageGenerator::Result result = fImageGenerator->getPixels(info,
+                fLockedBitmap.getPixels(), fRowBytes);
+        switch (result) {
+            case SkImageGenerator::kIncompleteInput:
+            case SkImageGenerator::kSuccess:
+                break;
+            default:
+                fErrorInDecoding = true;
+                return false;
         }
         fLockedBitmap.setImmutable();
         SkBitmapCache::Add(