SkGIFMovie: Fix corrupted background color

The 'paintingColor' in onGetBitmap() was used to save the entire
gif's background color while filling the 1st frame of a gif image,
since it is 'static' qualified, so when re-entering this function
for subsequent frames, this saved value will be used directly without
re-obtaining it.
But if asynchronous playing multi gif files in single process without
being controlled, this 'static' will make the 'paintingColor'
corrupted, because the different SkGIFMovie instances hold the same
reference of 'paintingColor'.

Signed-off-by: Lu Tong <lu.x.tong@sonymobile.com>;

BUG=skia:

Review URL: https://codereview.chromium.org/1184083002

1 files changed, 7 insertions, 6 deletions

diff --git a/src/images/SkMovie_gif.cpp b/src/images/SkMovie_gif.cpp
index 40e5520def..380aca499a 100644
--- a/src/images/SkMovie_gif.cpp
+++ b/src/images/SkMovie_gif.cpp
@@ -35,6 +35,7 @@ private:
     int fCurrIndex;
     int fLastDrawIndex;
     SkBitmap fBackup;
+    SkColor fPaintingColor;
 };
 
 static int Decode(GifFileType* fileType, GifByteType* out, int size) {
@@ -59,6 +60,7 @@ SkGIFMovie::SkGIFMovie(SkStream* stream)
     }
     fCurrIndex = -1;
     fLastDrawIndex = -1;
+    fPaintingColor = SkPackARGB32(0, 0, 0, 0);
 }
 
 SkGIFMovie::~SkGIFMovie()
@@ -395,7 +397,6 @@ bool SkGIFMovie::onGetBitmap(SkBitmap* bm)
         bgColor = SkColorSetARGB(0xFF, col.Red, col.Green, col.Blue);
     }
 
-    static SkColor paintingColor = SkPackARGB32(0, 0, 0, 0);
     // draw each frames - not intelligent way
     for (int i = startIndex; i <= lastIndex; i++) {
         const SavedImage* cur = &fGIF->SavedImages[i];
@@ -404,17 +405,17 @@ bool SkGIFMovie::onGetBitmap(SkBitmap* bm)
             int disposal;
             getTransparencyAndDisposalMethod(cur, &trans, &disposal);
             if (!trans && gif->SColorMap != NULL) {
-                paintingColor = bgColor;
+                fPaintingColor = bgColor;
             } else {
-                paintingColor = SkColorSetARGB(0, 0, 0, 0);
+                fPaintingColor = SkColorSetARGB(0, 0, 0, 0);
             }
 
-            bm->eraseColor(paintingColor);
-            fBackup.eraseColor(paintingColor);
+            bm->eraseColor(fPaintingColor);
+            fBackup.eraseColor(fPaintingColor);
         } else {
             // Dispose previous frame before move to next frame.
             const SavedImage* prev = &fGIF->SavedImages[i-1];
-            disposeFrameIfNeeded(bm, prev, cur, &fBackup, paintingColor);
+            disposeFrameIfNeeded(bm, prev, cur, &fBackup, fPaintingColor);
         }
 
         // Draw frame