Scanline decoding for gifs

src/codec/SkScaledCodec.cpp

Index: src/codec/SkScaledCodec.cpp
diff --git a/src/codec/SkScaledCodec.cpp b/src/codec/SkScaledCodec.cpp
index a9e067eaaf6f07a0ba553436f2bda13d7fa0179b..cf678db8565d0b131d359b28ab6256379e825971 100644
--- a/src/codec/SkScaledCodec.cpp
+++ b/src/codec/SkScaledCodec.cpp
@@ -44,15 +44,6 @@ SkScaledCodec::SkScaledCodec(SkScanlineDecoder* scanlineDecoder)
 
 SkScaledCodec::~SkScaledCodec() {}
 
-// returns a scaled dimension based on the original dimension and the sampleSize
-// NOTE: we round down here for scaled dimension to match the behavior of SkImageDecoder
-static int get_scaled_dimension(int srcDimension, int sampleSize) {
-    if (sampleSize > srcDimension) {
-        return 1;
-    }
-    return srcDimension / sampleSize;
-}
-
 static SkISize best_scaled_dimensions(const SkISize& origDims, const SkISize& nativeDims,
                                       const SkISize& scaledCodecDims, float desiredScale) {
     if (nativeDims == scaledCodecDims) {
@@ -197,7 +188,25 @@ SkCodec::Result SkScaledCodec::onGetPixels(const SkImageInfo& requestedInfo, voi
     Result result = fScanlineDecoder->start(requestedInfo, &options, ctable, ctableCount);
     if (kSuccess == result) {
         // native decode supported
-        return fScanlineDecoder->getScanlines(dst, requestedInfo.height(), rowBytes);
+        switch (fScanlineDecoder->getScanlineOrder()) {
+            case SkScanlineDecoder::kTopDown_SkScanlineOrder:
+            case SkScanlineDecoder::kBottomUp_SkScanlineOrder:
+            case SkScanlineDecoder::kNone_SkScanlineOrder:
+                return fScanlineDecoder->getScanlines(dst, requestedInfo.height(), rowBytes);
+            case SkScanlineDecoder::kOutOfOrder_SkScanlineOrder: {
+                for (int y = 0; y < requestedInfo.height(); y++) {
+                    int dstY = fScanlineDecoder->getY();
+                    void* dstPtr = SkTAddOffset<void>(dst, rowBytes * dstY);
+                    result = fScanlineDecoder->getScanlines(dstPtr, 1, rowBytes);
+                    // FIXME (msarett): Make the SkCodec base class take care of filling
+                    // uninitialized pixels so we can return immediately on kIncompleteInput.
+                    if (kSuccess != result && kIncompleteInput != result) {
+                        return result;
+                    }
+                }
+                return result;
+            }
+        }
     }
 
     if (kInvalidScale != result) {
@@ -246,7 +255,7 @@ SkCodec::Result SkScaledCodec::onGetPixels(const SkImageInfo& requestedInfo, voi
                 }
                 dst = SkTAddOffset<void>(dst, rowBytes);
             }
-            return kSuccess;
+            return result;
         }
         case SkScanlineDecoder::kBottomUp_SkScanlineOrder:
         case SkScanlineDecoder::kOutOfOrder_SkScanlineOrder: {
@@ -265,13 +274,13 @@ SkCodec::Result SkScaledCodec::onGetPixels(const SkImageInfo& requestedInfo, voi
                     }
                 }
             }
-            return kSuccess;
+            return result;
         }
         case SkScanlineDecoder::kNone_SkScanlineOrder: {
             SkAutoMalloc storage(srcHeight * rowBytes);
             uint8_t* storagePtr = static_cast<uint8_t*>(storage.get());
             result = fScanlineDecoder->getScanlines(storagePtr, srcHeight, rowBytes);
-            if (kSuccess != result) {
+            if (kSuccess != result && kIncompleteInput != result) {
                 return result;
             }
             storagePtr += Y0 * rowBytes;
@@ -280,7 +289,7 @@ SkCodec::Result SkScaledCodec::onGetPixels(const SkImageInfo& requestedInfo, voi
                 storagePtr += sampleY * rowBytes;
                 dst = SkTAddOffset<void>(dst, rowBytes);
             }
-            return kSuccess;
+            return result;
         }
         default:
             SkASSERT(false);