Scanline decoding for bmp

dm/DMSrcSink.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 "DMSrcSink.h"
 #include "SamplePipeControllers.h"
 #include "SkCodec.h"
@@ skipping 61 matching lines @@
 {}
 
 bool CodecSrc::veto(SinkFlags flags) const {
     // No need to test decoding to non-raster or indirect backend.
     // TODO: Once we implement GPU paths (e.g. JPEG YUV), we should use a deferred decode to
     // let the GPU handle it.
     return flags.type != SinkFlags::kRaster
         || flags.approach != SinkFlags::kDirect;
 }
 
+SkScanlineDecoder* start_scanline_decoder(SkData* encoded, const SkImageInfo& info,
+        SkPMColor* colorPtr, int* colorCountPtr) {
+    SkAutoTDelete<SkScanlineDecoder> scanlineDecoder(SkScanlineDecoder::NewFromData(encoded));
+    if (nullptr == scanlineDecoder) {
+        return nullptr;
+    }
+    // DM scanline test assume kTopDown scanline ordering.  Other orderings are
+    // tested from within SkScaledCodec.
+    // TODO (msarett): Redesign the CodecSrc tests to improve our coverage of SkCodec and
+    //                 SkScanlineDecoder functionality.  Maybe we should write code to explicitly
+    //                 test kNone, kOutOfOrder, and kBottomUp.
+    if (SkScanlineDecoder::kTopDown_SkScanlineOrder != scanlineDecoder->getScanlineOrder()) {
+        return nullptr;
+    }
+    if (SkCodec::kSuccess != scanlineDecoder->start(info, NULL, colorPtr, colorCountPtr)) {
+        return nullptr;
+    }
+    return scanlineDecoder.detach();
+}
+
 Error CodecSrc::draw(SkCanvas* canvas) const {
     SkAutoTUnref<SkData> encoded(SkData::NewFromFileName(fPath.c_str()));
     if (!encoded) {
         return SkStringPrintf("Couldn't read %s.", fPath.c_str());
     }
     SkAutoTDelete<SkCodec> codec(SkScaledCodec::NewFromData(encoded));
     if (nullptr == codec.get()) {
         // scaledCodec not supported, try normal codec
         codec.reset(SkCodec::NewFromData(encoded));
         if (nullptr == codec.get()) {
@@ skipping 71 matching lines @@
                     return Error::Nonfatal("Incompatible colortype conversion");
                 default:
                     // Everything else is considered a failure.
                     return SkStringPrintf("Couldn't getPixels %s.", fPath.c_str());
             }
             canvas->drawBitmap(bitmap, 0, 0);
             break;
         }
         case kScanline_Mode: {
             SkAutoTDelete<SkScanlineDecoder> scanlineDecoder(
-                    SkScanlineDecoder::NewFromData(encoded));
-            if (nullptr == scanlineDecoder || SkCodec::kSuccess !=
-                    scanlineDecoder->start(decodeInfo, nullptr, colorPtr, colorCountPtr)) {
-                return Error::Nonfatal("Cannot use scanline decoder for all images");
+                    start_scanline_decoder(encoded.get(), decodeInfo, colorPtr, colorCountPtr));
+            if (nullptr == scanlineDecoder) {
+                return Error::Nonfatal("Could not start top-down scanline decoder");
             }
 
             const SkCodec::Result result = scanlineDecoder->getScanlines(
                     bitmap.getAddr(0, 0), decodeInfo.height(), bitmap.rowBytes());
             switch (result) {
                 case SkCodec::kSuccess:
                 case SkCodec::kIncompleteInput:
                     break;
                 default:
                     return SkStringPrintf("%s failed with error message %d",
@@ skipping 40 matching lines @@
                 const int currentSubsetWidth = (col + 1 == divisor) ?
                         subsetWidth + extraX : subsetWidth;
                 const int x = col * subsetWidth;
                 for (int row = 0; row < divisor; row++) {
                     //currentSubsetHeight may be larger than subsetHeight for bottom subsets
                     const int currentSubsetHeight = (row + 1 == divisor) ?
                             subsetHeight + extraY : subsetHeight;
                     const int y = row * subsetHeight;
                     //create scanline decoder for each subset
                     SkAutoTDelete<SkScanlineDecoder> subsetScanlineDecoder(
-                            SkScanlineDecoder::NewFromData(encoded));
-                    if (nullptr == subsetScanlineDecoder || SkCodec::kSuccess !=
-                            subsetScanlineDecoder->start(
-                            decodeInfo, nullptr, colorPtr, colorCountPtr))
-                    {
+                            start_scanline_decoder(encoded.get(), decodeInfo,
+                                    colorPtr, colorCountPtr));
+                    if (nullptr == subsetScanlineDecoder) {
                         if (x == 0 && y == 0) {
                             //first try, image may not be compatible
-                            return Error::Nonfatal("Cannot use scanline decoder for all images");
+                            return Error::Nonfatal("Could not start top-down scanline decoder");
                         } else {
                             return "Error scanline decoder is nullptr";
                         }
                     }
                     //skip to first line of subset
                     const SkCodec::Result skipResult =
                             subsetScanlineDecoder->skipScanlines(y);
                     switch (skipResult) {
                         case SkCodec::kSuccess:
                         case SkCodec::kIncompleteInput:
@@ skipping 42 matching lines @@
             break;
         }
         case kStripe_Mode: {
             const int height = decodeInfo.height();
             // This value is chosen arbitrarily.  We exercise more cases by choosing a value that
             // does not align with image blocks.
             const int stripeHeight = 37;
             const int numStripes = (height + stripeHeight - 1) / stripeHeight;
 
             // Decode odd stripes
-            SkAutoTDelete<SkScanlineDecoder> decoder(SkScanlineDecoder::NewFromData(encoded));
-            if (nullptr == decoder || SkCodec::kSuccess !=
-                    decoder->start(decodeInfo, nullptr, colorPtr, colorCountPtr)) {
-                return Error::Nonfatal("Cannot use scanline decoder for all images");
+            SkAutoTDelete<SkScanlineDecoder> decoder(
+                    start_scanline_decoder(encoded.get(), decodeInfo, colorPtr, colorCountPtr));
+            if (nullptr == decoder) {
+                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:
@@ skipping 743 matching lines @@
             skr.visit<void>(i, drawsAsSingletonPictures);
         }
         SkAutoTUnref<SkPicture> macroPic(macroRec.endRecordingAsPicture());
 
         canvas->drawPicture(macroPic);
         return "";
     });
 }
 
 }  // namespace DM