Fill incomplete images in SkCodec parent class

dm/DMSrcSink.cpp

Index: dm/DMSrcSink.cpp
diff --git a/dm/DMSrcSink.cpp b/dm/DMSrcSink.cpp
index 981e47d6c0bf84690c25c8a49392fa2e3abadc18..5a8a071ece41cf8ff67a498801bf1d8bdfa24b04 100644
--- a/dm/DMSrcSink.cpp
+++ b/dm/DMSrcSink.cpp
@@ -352,35 +352,33 @@ Error CodecSrc::draw(SkCanvas* canvas) const {
                 return Error::Nonfatal("Could not start scanline decoder");
             }
 
-            SkCodec::Result result = SkCodec::kUnimplemented;
+            uint32_t linesDecoded = 0;
             switch (scanlineDecoder->getScanlineOrder()) {
                 case SkScanlineDecoder::kTopDown_SkScanlineOrder:
                 case SkScanlineDecoder::kBottomUp_SkScanlineOrder:
                 case SkScanlineDecoder::kNone_SkScanlineOrder:
-                    result = scanlineDecoder->getScanlines(bitmap.getAddr(0, 0),
+                    linesDecoded = scanlineDecoder->getScanlines(bitmap.getAddr(0, 0),
                             decodeInfo.height(), bitmap.rowBytes());
                     break;
                 case SkScanlineDecoder::kOutOfOrder_SkScanlineOrder: {
                     for (int y = 0; y < decodeInfo.height(); y++) {
                         int dstY = scanlineDecoder->getY();
                         void* dstPtr = bitmap.getAddr(0, dstY);
-                        result = scanlineDecoder->getScanlines(dstPtr, 1, bitmap.rowBytes());
-                        if (SkCodec::kSuccess != result && SkCodec::kIncompleteInput != result) {
-                            return SkStringPrintf("%s failed with error message %d",
-                                                  fPath.c_str(), (int) result);
+                        uint32_t line = scanlineDecoder->getScanlines(dstPtr, 1, bitmap.rowBytes());
+                        if (1 != line) {
+                            break;
                         }
+                        linesDecoded += line;
                     }
                     break;
                 }
             }
-
-            switch (result) {
-                case SkCodec::kSuccess:
-                case SkCodec::kIncompleteInput:
-                    break;
-                default:
-                    return SkStringPrintf("%s failed with error message %d",
-                                          fPath.c_str(), (int) result);
+            if ((int) linesDecoded < decodeInfo.height()) {
+                // We have not implemented a function in SkScanlineDecoder to fill remaining
+                // scanlines on an incomplete decode.  As long as we are the only client that
+                // uses SkScanlineDecoder, I think this is ok.  If this changes, maybe we want
+                // to consider providing an API for this?
+                return Error::Nonfatal("Image is incomplete, could not get scanlines");
             }
             canvas->drawBitmap(bitmap, 0, 0);
             break;
@@ -443,14 +441,8 @@ Error CodecSrc::draw(SkCanvas* canvas) const {
                         }
                     }
                     //skip to first line of subset
-                    const SkCodec::Result skipResult = decoder->skipScanlines(y);
-                    switch (skipResult) {
-                        case SkCodec::kSuccess:
-                        case SkCodec::kIncompleteInput:
-                            break;
-                        default:
-                            return SkStringPrintf("%s failed after attempting to skip %d scanlines"
-                                    "with error message %d", fPath.c_str(), y, (int) skipResult);
+                    if (!decoder->skipScanlines(y)) {
+                        return Error::Nonfatal("Image is incomplete, could not get scanlines");
                     }
                     //create and set size of subsetBm
                     SkBitmap subsetBm;
@@ -458,15 +450,9 @@ Error CodecSrc::draw(SkCanvas* canvas) const {
                     bounds.setXYWH(0, 0, currentSubsetWidth, currentSubsetHeight);
                     SkAssertResult(largestSubsetBm.extractSubset(&subsetBm, bounds));
                     SkAutoLockPixels autlockSubsetBm(subsetBm, true);
-                    const SkCodec::Result subsetResult =
-                            decoder->getScanlines(buffer, currentSubsetHeight, rowBytes);
-                    switch (subsetResult) {
-                        case SkCodec::kSuccess:
-                        case SkCodec::kIncompleteInput:
-                            break;
-                        default:
-                            return SkStringPrintf("%s failed with error message %d",
-                                    fPath.c_str(), (int) subsetResult);
+                    if ((int) decoder->getScanlines(buffer, currentSubsetHeight, rowBytes) <
+                            currentSubsetHeight) {
+                        return Error::Nonfatal("Image is incomplete, could not get scanlines");
                     }
                     const size_t bpp = decodeInfo.bytesPerPixel();
                     /*
@@ -508,30 +494,21 @@ Error CodecSrc::draw(SkCanvas* canvas) const {
                 // to run this test for image types that do not have this scanline ordering.
                 return Error::Nonfatal("Could not start top-down scanline decoder");
             }
+
             for (int i = 0; i < numStripes; i += 2) {
                 // Skip a stripe
                 const int linesToSkip = SkTMin(stripeHeight, height - i * stripeHeight);
-                SkCodec::Result result = decoder->skipScanlines(linesToSkip);
-                switch (result) {
-                    case SkCodec::kSuccess:
-                    case SkCodec::kIncompleteInput:
-                        break;
-                    default:
-                        return SkStringPrintf("Cannot skip scanlines for %s.", fPath.c_str());
+                if (!decoder->skipScanlines(linesToSkip)) {
+                    return Error::Nonfatal("Image is incomplete, could not get scanlines");
                 }
 
                 // Read a stripe
                 const int startY = (i + 1) * stripeHeight;
                 const int linesToRead = SkTMin(stripeHeight, height - startY);
                 if (linesToRead > 0) {
-                    result = decoder->getScanlines(bitmap.getAddr(0, startY),
-                            linesToRead, bitmap.rowBytes());
-                    switch (result) {
-                        case SkCodec::kSuccess:
-                        case SkCodec::kIncompleteInput:
-                            break;
-                        default:
-                            return SkStringPrintf("Cannot get scanlines for %s.", fPath.c_str());
+                    if ((int) decoder->getScanlines(bitmap.getAddr(0, startY), linesToRead,
+                            bitmap.rowBytes()) < linesToRead) {
+                        return Error::Nonfatal("Image is incomplete, could not get scanlines");
                     }
                 }
             }
@@ -546,26 +523,16 @@ Error CodecSrc::draw(SkCanvas* canvas) const {
                 // Read a stripe
                 const int startY = i * stripeHeight;
                 const int linesToRead = SkTMin(stripeHeight, height - startY);
-                SkCodec::Result result = decoder->getScanlines(bitmap.getAddr(0, startY),
-                        linesToRead, bitmap.rowBytes());
-                switch (result) {
-                    case SkCodec::kSuccess:
-                    case SkCodec::kIncompleteInput:
-                        break;
-                    default:
-                        return SkStringPrintf("Cannot get scanlines for %s.", fPath.c_str());
+                if ((int) decoder->getScanlines(bitmap.getAddr(0, startY), linesToRead,
+                        bitmap.rowBytes()) < linesToRead) {
+                    return Error::Nonfatal("Image is incomplete, could not get scanlines");
                 }
 
                 // Skip a stripe
                 const int linesToSkip = SkTMin(stripeHeight, height - (i + 1) * stripeHeight);
                 if (linesToSkip > 0) {
-                    result = decoder->skipScanlines(linesToSkip);
-                    switch (result) {
-                        case SkCodec::kSuccess:
-                        case SkCodec::kIncompleteInput:
-                            break;
-                        default:
-                            return SkStringPrintf("Cannot skip scanlines for %s.", fPath.c_str());
+                    if (!decoder->skipScanlines(linesToSkip)) {
+                        return Error::Nonfatal("Image is incomplete, could not get scanlines");
                     }
                 }
             }