Use possible read_partial_scanlines() API in SkJpegCodec

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 "SkAndroidCodec.h"
@@ skipping 355 matching lines @@
                         codec->getScanlines(dstPtr, 1, bitmap.rowBytes());
                     }
                     break;
                 }
             }
 
             canvas->drawBitmap(bitmap, 0, 0);
             break;
         }
         case kStripe_Mode: {
+            const int width = decodeInfo.width();
             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
-            if (SkCodec::kSuccess != codec->startScanlineDecode(decodeInfo, NULL, colorPtr,
+            SkCodec::Options opts;
+            SkIRect subset = SkIRect::MakeXYWH(0, 0, width / 2, height);
+            opts.fSubset = ⊂
+            if (SkCodec::kSuccess != codec->startScanlineDecode(decodeInfo, &opts, colorPtr,
                                                                 colorCountPtr)
                     || SkCodec::kTopDown_SkScanlineOrder != codec->getScanlineOrder()) {
                 // This mode was designed to test the new skip scanlines API in libjpeg-turbo.
                 // Jpegs have kTopDown_SkScanlineOrder, and at this time, it is not interesting
                 // 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);
                 codec->skipScanlines(linesToSkip);
 
                 // Read a stripe
                 const int startY = (i + 1) * stripeHeight;
                 const int linesToRead = SkTMin(stripeHeight, height - startY);
                 if (linesToRead > 0) {
                     codec->getScanlines(bitmap.getAddr(0, startY), linesToRead, bitmap.rowBytes());
                 }
             }
 
             // Decode even stripes
-            const SkCodec::Result startResult = codec->startScanlineDecode(decodeInfo, nullptr,
+            SkCodec::Result startResult = codec->startScanlineDecode(decodeInfo, &opts,
                     colorPtr, colorCountPtr);
             if (SkCodec::kSuccess != startResult) {
                 return "Failed to restart scanline decoder with same parameters.";
             }
             for (int i = 0; i < numStripes; i += 2) {
                 // Read a stripe
                 const int startY = i * stripeHeight;
                 const int linesToRead = SkTMin(stripeHeight, height - startY);
                 codec->getScanlines(bitmap.getAddr(0, startY), linesToRead, bitmap.rowBytes());
 
                 // Skip a stripe
                 const int linesToSkip = SkTMin(stripeHeight, height - (i + 1) * stripeHeight);
                 if (linesToSkip > 0) {
                     codec->skipScanlines(linesToSkip);
                 }
             }
+
+            // Begin duplicated code
+            SkIRect nextSubset = SkIRect::MakeXYWH(width / 2, 0, width / 2 + width % 2, height);
+            opts.fSubset = &nextSubset;
+            startResult = codec->startScanlineDecode(decodeInfo, &opts, colorPtr, colorCountPtr);
+            if (SkCodec::kSuccess != startResult) {
+                return "Failed to restart scanline decoder with same parameters.";
+            }
+
+            for (int i = 0; i < numStripes; i += 2) {
+                // Skip a stripe
+                const int linesToSkip = SkTMin(stripeHeight, height - i * stripeHeight);
+                codec->skipScanlines(linesToSkip);
+
+                // Read a stripe
+                const int startY = (i + 1) * stripeHeight;
+                const int linesToRead = SkTMin(stripeHeight, height - startY);
+                if (linesToRead > 0) {
+                    codec->getScanlines(bitmap.getAddr(width / 2, startY), linesToRead,
+                            bitmap.rowBytes());
+                }
+            }
+
+            // Decode even stripes
+            startResult = codec->startScanlineDecode(decodeInfo, &opts, colorPtr, colorCountPtr);
+            if (SkCodec::kSuccess != startResult) {
+                return "Failed to restart scanline decoder with same parameters.";
+            }
+            for (int i = 0; i < numStripes; i += 2) {
+                // Read a stripe
+                const int startY = i * stripeHeight;
+                const int linesToRead = SkTMin(stripeHeight, height - startY);
+                codec->getScanlines(bitmap.getAddr(width / 2, startY), linesToRead, bitmap.rowBytes());
+
+                // Skip a stripe
+                const int linesToSkip = SkTMin(stripeHeight, height - (i + 1) * stripeHeight);
+                if (linesToSkip > 0) {
+                    codec->skipScanlines(linesToSkip);
+                }
+            }
+
+
             canvas->drawBitmap(bitmap, 0, 0);
             break;
         }
         case kSubset_Mode: {
             // Arbitrarily choose a divisor.
             int divisor = 2;
             // Total width/height of the image.
             const int W = codec->getInfo().width();
             const int H = codec->getInfo().height();
             if (divisor > W || divisor > H) {
@@ skipping 831 matching lines @@
             skr.visit<void>(i, drawsAsSingletonPictures);
         }
         SkAutoTUnref<SkPicture> macroPic(macroRec.endRecordingAsPicture());
 
         canvas->drawPicture(macroPic);
         return "";
     });
 }
 
 }  // namespace DM