Add subsetting to SkScanlineDecoder

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"
-#include "SkCodecTools.h"
+#include "SkCodecPriv.h"
 #include "SkCommonFlags.h"
 #include "SkData.h"
 #include "SkDocument.h"
 #include "SkError.h"
 #include "SkFunction.h"
 #include "SkImageGenerator.h"
 #include "SkMultiPictureDraw.h"
 #include "SkNullCanvas.h"
 #include "SkOSFile.h"
 #include "SkPictureData.h"
@@ skipping 57 matching lines @@
 bool BRDSrc::veto(SinkFlags flags) const {
     // No need to test to non-raster or indirect backends.
     return flags.type != SinkFlags::kRaster
         || flags.approach != SinkFlags::kDirect;
 }
 
 static SkBitmapRegionDecoderInterface* create_brd(Path path,
         SkBitmapRegionDecoderInterface::Strategy strategy) {
     SkAutoTUnref<SkData> encoded(SkData::NewFromFileName(path.c_str()));
     if (!encoded) {
-        return NULL;
+        return nullptr;
     }
     return SkBitmapRegionDecoderInterface::CreateBitmapRegionDecoder(new SkMemoryStream(encoded),
             strategy);
 }
 
 Error BRDSrc::draw(SkCanvas* canvas) const {
     SkColorType colorType = canvas->imageInfo().colorType();
     if (kRGB_565_SkColorType == colorType &&
             CodecSrc::kGetFromCanvas_DstColorType != fDstColorType) {
         return Error::Nonfatal("Testing non-565 to 565 is uninteresting.");
@@ skipping 137 matching lines @@
     // let the GPU handle it.
     return flags.type != SinkFlags::kRaster
         || flags.approach != SinkFlags::kDirect;
 }
 
 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(NULL);
+    SkAutoTDelete<SkCodec> codec(nullptr);
     if (kScaledCodec_Mode == fMode) {
         codec.reset(SkScaledCodec::NewFromData(encoded));
         // TODO (msarett): This should fall through to a fatal error once we support scaled
         //                 codecs for all image types.
         if (nullptr == codec.get()) {
             return Error::Nonfatal(SkStringPrintf("Couldn't create scaled codec for %s.",
                     fPath.c_str()));
         }
     } else {
         codec.reset(SkCodec::NewFromData(encoded));
@@ skipping 135 matching lines @@
             * subsets.
             */
             SkImageInfo largestSubsetDecodeInfo =
                     decodeInfo.makeWH(subsetWidth + extraX, subsetHeight + extraY);
             SkBitmap largestSubsetBm;
             if (!largestSubsetBm.tryAllocPixels(largestSubsetDecodeInfo, nullptr,
                     colorTable.get())) {
                 return SkStringPrintf("Image(%s) is too large (%d x %d)\n", fPath.c_str(),
                         largestSubsetDecodeInfo.width(), largestSubsetDecodeInfo.height());
             }
-            const size_t rowBytes = decodeInfo.minRowBytes();
-            char* buffer = new char[largestSubsetDecodeInfo.height() * rowBytes];
-            SkAutoTDeleteArray<char> lineDeleter(buffer);
             for (int col = 0; col < divisor; col++) {
                 //currentSubsetWidth may be larger than subsetWidth for rightmost subsets
                 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
-                    if (SkCodec::kSuccess != codec->startScanlineDecode(decodeInfo, NULL, colorPtr,
-                                                                        colorCountPtr)
-                            // TODO (msarett): Support this mode for all scanline orderings.
-                            || SkCodec::kTopDown_SkScanlineOrder != codec->getScanlineOrder()) {
+                    SkCodec::Options options;
+                    SkIRect subset = SkIRect::MakeXYWH(x, 0, currentSubsetWidth, h);
+                    options.fSubset = &subset;
+                    // TODO (msarett): Support this mode for all scanline orderings.
+                    if (SkCodec::kSuccess != codec->startScanlineDecode(decodeInfo, &options,
+                            colorPtr, colorCountPtr) ||
+                            SkCodec::kTopDown_SkScanlineOrder != codec->getScanlineOrder()) {
                         if (x == 0 && y == 0) {
                             //first try, image may not be compatible
                             return Error::Nonfatal("Could not start top-down scanline decoder");
                         } else {
                             return "Error scanline decoder is nullptr";
                         }
                     }
                     // Skip to the first line of subset.  We ignore the result value here.
                     // If the skip value fails, this will indicate an incomplete image.
                     // This means that the call to getScanlines() will also fail, but it
                     // will fill the buffer with a default value, so we can still draw the
                     // image.
                     codec->skipScanlines(y);
 
                     //create and set size of subsetBm
-                    SkBitmap subsetBm;
+                    SkBitmap bitmap;

[scroggo, 2015/10/08 20:16:07]

Why did you change this name? The comment above no longer applies, and you have
shadowed the variable "bitmap" in an outer scope (the fact that I had to look up
100 lines is evidence this function is too big...).

[msarett, 2015/10/09 20:03:44]

Can't remember.  Changing it back sorry.

                     SkIRect bounds = SkIRect::MakeWH(currentSubsetWidth, currentSubsetHeight);
-                    SkAssertResult(largestSubsetBm.extractSubset(&subsetBm, bounds));
-                    SkAutoLockPixels autlockSubsetBm(subsetBm, true);
-                    codec->getScanlines(buffer, currentSubsetHeight, rowBytes);
-
-                    const size_t bpp = decodeInfo.bytesPerPixel();
-                    char* bufferRow = buffer;
-                    for (int subsetY = 0; subsetY < currentSubsetHeight; ++subsetY) {
-                        memcpy(subsetBm.getAddr(0, subsetY), bufferRow + x*bpp,
-                                currentSubsetWidth*bpp);
-                        bufferRow += rowBytes;
-                    }
-
-                    subsetBm.notifyPixelsChanged();
-                    canvas->drawBitmap(subsetBm, SkIntToScalar(x), SkIntToScalar(y));
+                    SkAssertResult(largestSubsetBm.extractSubset(&bitmap, bounds));
+                    SkAutoLockPixels autolock(bitmap, true);
+                    codec->getScanlines(bitmap.getAddr(0, 0), currentSubsetHeight,
+                            bitmap.rowBytes());
+                    bitmap.notifyPixelsChanged();
+                    canvas->drawBitmap(bitmap, SkIntToScalar(x), SkIntToScalar(y));
                 }
             }
             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;
@@ skipping 742 matching lines @@
             skr.visit<void>(i, drawsAsSingletonPictures);
         }
         SkAutoTUnref<SkPicture> macroPic(macroRec.endRecordingAsPicture());
 
         canvas->drawPicture(macroPic);
         return "";
     });
 }
 
 }  // namespace DM