Fill incomplete images in SkCodec parent class

src/codec/SkBmpRLECodec.cpp

Index: src/codec/SkBmpRLECodec.cpp
diff --git a/src/codec/SkBmpRLECodec.cpp b/src/codec/SkBmpRLECodec.cpp
index e76a23ed14ad78ac93f9bd6b73a24ce69beb6f31..aff4a0616423d60d8bb74a149d213d8ed394d03e 100644
--- a/src/codec/SkBmpRLECodec.cpp
+++ b/src/codec/SkBmpRLECodec.cpp
@@ -38,7 +38,8 @@ SkCodec::Result SkBmpRLECodec::onGetPixels(const SkImageInfo& dstInfo,
                                            void* dst, size_t dstRowBytes,
                                            const Options& opts,
                                            SkPMColor* inputColorPtr,
-                                           int* inputColorCount) {
+                                           int* inputColorCount,
+                                           int* rowsDecoded) {
     if (opts.fSubset) {
         // Subsets are not supported.
         return kUnimplemented;
@@ -58,7 +59,14 @@ SkCodec::Result SkBmpRLECodec::onGetPixels(const SkImageInfo& dstInfo,
     }
 
     // Perform the decode
-    return this->decodeRows(dstInfo, dst, dstRowBytes, opts);
+    uint32_t rows = this->decodeRows(dstInfo, dst, dstRowBytes, opts);
+    if (rows != dstInfo.height()) {
+        // We set rowsDecoded equal to the height because the background has already
+        // been filled.  RLE encodings sometimes skip pixels, so we always start by
+        // filling the background.
+        *rowsDecoded = dstInfo.height();
+        return kIncompleteInput;
+    }
 }
 
 /*
@@ -278,9 +286,8 @@ SkCodec::Result SkBmpRLECodec::prepareToDecode(const SkImageInfo& dstInfo,
  * Performs the bitmap decoding for RLE input format
  * RLE decoding is performed all at once, rather than a one row at a time
  */
-SkCodec::Result SkBmpRLECodec::decodeRows(const SkImageInfo& dstInfo,
-                                          void* dst, size_t dstRowBytes,
-                                          const Options& opts) {
+uint32_t SkBmpRLECodec::decodeRows(const SkImageInfo& dstInfo, void* dst, size_t dstRowBytes,
+        const Options& opts) {
     // Set RLE flags
     static const uint8_t RLE_ESCAPE = 0;
     static const uint8_t RLE_EOL = 0;
@@ -300,24 +307,23 @@ SkCodec::Result SkBmpRLECodec::decodeRows(const SkImageInfo& dstInfo,
     // Because of the need for transparent pixels, kN32 is the only color
     // type that makes sense for the destination format.
     SkASSERT(kN32_SkColorType == dstInfo.colorType());
-    SkSwizzler::Fill(dst, dstInfo, dstRowBytes, height, SK_ColorTRANSPARENT,
-            NULL, opts.fZeroInitialized);
+    SkSwizzler::Fill(dst, dstInfo, dstRowBytes, SK_ColorTRANSPARENT, opts.fZeroInitialized);
 
     while (true) {
         // If we have reached a row that is beyond the requested height, we have
         // succeeded.
         if (y >= height) {
-            // It would be better to check for the EOF marker before returning
+            // It would be better to check for the EOF marker before indicating
             // success, but we may be performing a scanline decode, which
-            // may require us to stop before decoding the full height.
-            return kSuccess;
+            // would require us to stop before decoding the full height.
+            return height;
         }
 
         // Every entry takes at least two bytes
         if ((int) fRLEBytes - fCurrRLEByte < 2) {
             SkCodecPrintf("Warning: might be incomplete RLE input.\n");
             if (this->checkForMoreData() < 2) {
-                return kIncompleteInput;
+                return y;
             }
         }
 
@@ -342,7 +348,7 @@ SkCodec::Result SkBmpRLECodec::decodeRows(const SkImageInfo& dstInfo,
                     if ((int) fRLEBytes - fCurrRLEByte < 2) {
                         SkCodecPrintf("Warning: might be incomplete RLE input.\n");
                         if (this->checkForMoreData() < 2) {
-                            return kIncompleteInput;
+                            return y;
                         }
                     }
                     // Modify x and y
@@ -352,7 +358,7 @@ SkCodec::Result SkBmpRLECodec::decodeRows(const SkImageInfo& dstInfo,
                     y += dy;
                     if (x > width || y > height) {
                         SkCodecPrintf("Warning: invalid RLE input.\n");
-                        return kInvalidInput;
+                        return y - dy;
                     }
                     break;
                 }
@@ -368,14 +374,14 @@ SkCodec::Result SkBmpRLECodec::decodeRows(const SkImageInfo& dstInfo,
                     // image.
                     if (x + numPixels > width) {
                         SkCodecPrintf("Warning: invalid RLE input.\n");
-                        return kInvalidInput;
+                        return y;
                     }
                     // Also abort if there are not enough bytes
                     // remaining in the stream to set numPixels.
                     if ((int) fRLEBytes - fCurrRLEByte < SkAlign2(rowBytes)) {
                         SkCodecPrintf("Warning: might be incomplete RLE input.\n");
                         if (this->checkForMoreData() < SkAlign2(rowBytes)) {
-                            return kIncompleteInput;
+                            return y;
                         }
                     }
                     // Set numPixels number of pixels
@@ -411,7 +417,7 @@ SkCodec::Result SkBmpRLECodec::decodeRows(const SkImageInfo& dstInfo,
                             }
                             default:
                                 SkASSERT(false);
-                                return kInvalidInput;
+                                return y;
                         }
                     }
                     // Skip a byte if necessary to maintain alignment
@@ -434,7 +440,7 @@ SkCodec::Result SkBmpRLECodec::decodeRows(const SkImageInfo& dstInfo,
                 if ((int) fRLEBytes - fCurrRLEByte < 2) {
                     SkCodecPrintf("Warning: might be incomplete RLE input.\n");
                     if (this->checkForMoreData() < 2) {
-                        return kIncompleteInput;
+                        return y;
                     }
                 }