Fill incomplete images in SkCodec parent class

src/codec/SkBmpMaskCodec.cpp

Index: src/codec/SkBmpMaskCodec.cpp
diff --git a/src/codec/SkBmpMaskCodec.cpp b/src/codec/SkBmpMaskCodec.cpp
index 3036f337b7f02b21803c70ff6b4ae3895d20edd0..5074a95f6550e9893be58ce33be82348424d0295 100644
--- a/src/codec/SkBmpMaskCodec.cpp
+++ b/src/codec/SkBmpMaskCodec.cpp
@@ -29,7 +29,8 @@ SkCodec::Result SkBmpMaskCodec::onGetPixels(const SkImageInfo& dstInfo,
                                             void* dst, size_t dstRowBytes,
                                             const Options& opts,
                                             SkPMColor* inputColorPtr,
-                                            int* inputColorCount) {
+                                            int* inputColorCount,
+                                            int* incompleteScanlines) {
     if (!this->rewindIfNeeded()) {
         return kCouldNotRewind;
     }
@@ -52,7 +53,12 @@ SkCodec::Result SkBmpMaskCodec::onGetPixels(const SkImageInfo& dstInfo,
         return result;
     }
 
-    return this->decodeRows(dstInfo, dst, dstRowBytes, opts);
+    uint32_t rows = this->decodeRows(dstInfo, dst, dstRowBytes, opts);
+    if (rows != dstInfo.height()) {
+        *incompleteScanlines = dstInfo.height() - rows;

[scroggo, 2015/09/25 15:55:05]

It's a little weird to me that onGetScanlines returns the number of rows that
were decoded, and onGetPixels returns the number that were *not* decoded. I
think this would be better to return the number successfully decoded. This means
you don't need to subtract here (and presumably, in the other subclasses), but
can subtract once in the base class.

[msarett, 2015/10/01 12:44:52]

Done.

+        return kIncompleteInput;
+    }
+    return kSuccess;
 }
 
 bool SkBmpMaskCodec::initializeSwizzler(const SkImageInfo& dstInfo) {
@@ -81,7 +87,7 @@ SkCodec::Result SkBmpMaskCodec::prepareToDecode(const SkImageInfo& dstInfo,
 /*
  * Performs the decoding
  */
-SkCodec::Result SkBmpMaskCodec::decodeRows(const SkImageInfo& dstInfo,
+uint32_t SkBmpMaskCodec::decodeRows(const SkImageInfo& dstInfo,
                                            void* dst, size_t dstRowBytes,
                                            const Options& opts) {
     // Iterate over rows of the image
@@ -91,12 +97,7 @@ SkCodec::Result SkBmpMaskCodec::decodeRows(const SkImageInfo& dstInfo,
         // Read a row of the input
         if (this->stream()->read(srcRow, fSrcRowBytes) != fSrcRowBytes) {
             SkCodecPrintf("Warning: incomplete input stream.\n");
-            // Fill the destination image on failure
-            void* dstStart = this->getDstStartRow(dst, dstRowBytes, y);
-            uint32_t fillColor = get_fill_color_or_index(dstInfo.alphaType());
-            SkSwizzler::Fill(dstStart, dstInfo, dstRowBytes, height - y,
-                    fillColor, nullptr, opts.fZeroInitialized);
-            return kIncompleteInput;
+            return y;
         }
 
         // Decode the row in destination format
@@ -106,5 +107,5 @@ SkCodec::Result SkBmpMaskCodec::decodeRows(const SkImageInfo& dstInfo,
     }
 
     // Finished decoding the entire image
-    return kSuccess;
+    return height;
 }