Fix some SkCodecPrintfs

src/codec/SkCodec.cpp

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkBmpCodec.h"
 #include "SkCodec.h"
 #include "SkData.h"
@@ skipping 44 matching lines @@
     size_t bytesRead = stream->peek(buffer, bytesToRead);
 
     // It is also possible to have a complete image less than bytesToRead bytes
     // (e.g. a 1 x 1 wbmp), meaning peek() would return less than bytesToRead.
     // Assume that if bytesRead < bytesToRead, but > 0, the stream is shorter
     // than bytesToRead, so pass that directly to the decoder.
     // It also is possible the stream uses too small a buffer for peeking, but
     // we trust the caller to use a large enough buffer.
 
     if (0 == bytesRead) {
-        SkCodecPrintf("Could not peek!\n");
+        // TODO: After implementing peek in CreateJavaOutputStreamAdaptor.cpp, this
+        // printf could be useful to notice failures.
+        // SkCodecPrintf("Encoded image data failed to peek!\n");
+
         // It is possible the stream does not support peeking, but does support
         // rewinding.
         // Attempt to read() and pass the actual amount read to the decoder.
         bytesRead = stream->read(buffer, bytesToRead);
         if (!stream->rewind()) {
-            SkCodecPrintf("Could not rewind!\n");
+            SkCodecPrintf("Encoded image data could not peek or rewind to determine format!\n");

[scroggo, 2016/01/06 16:57:52]

I could imagine making SkCodecPrintf add something that identifies it as codec
related.

[msarett, 2016/01/06 17:11:27]

Yes I agree.

             return nullptr;
         }
     }
 
     SkAutoTDelete<SkCodec> codec(nullptr);
     // PNG is special, since we want to be able to supply an SkPngChunkReader.
     // But this code follows the same pattern as the loop.
     if (SkPngCodec::IsPng(buffer, bytesRead)) {
         codec.reset(SkPngCodec::NewFromStream(streamDeleter.detach(), chunkReader));
     } else {
@@ skipping 292 matching lines @@
             SkASSERT(1 == linesRequested || this->getInfo().height() == linesRequested);
             const SkImageInfo fillInfo = info.makeWH(info.width(), 1);
             for (int srcY = linesDecoded; srcY < linesRequested; srcY++) {
                 fillDst = SkTAddOffset<void>(dst, this->outputScanline(srcY) * rowBytes);
                 fill_proc(fillInfo, fillDst, rowBytes, fillValue, zeroInit, sampler);
             }
             break;
         }
     }
 }