New CodeSrc* draw mode kScanline_Subset_Mode
kScanline_Subset_Mode decodes the image in subsets using a
scanline decoder.
The number of subsets can be specified by changing the constant divisor.
The number of subsets is equal to divisor*divisor.
Review URL: https://codereview.chromium.org/1157153003
diff --git a/dm/DMSrcSink.cpp b/dm/DMSrcSink.cpp
index 090a24d..a838511 100644
--- a/dm/DMSrcSink.cpp
+++ b/dm/DMSrcSink.cpp
@@ -141,6 +141,7 @@
// Everything else is considered a failure.
return SkStringPrintf("Couldn't getPixels %s.", fPath.c_str());
}
+ canvas->drawBitmap(bitmap, 0, 0);
break;
case kScanline_Mode: {
SkScanlineDecoder* scanlineDecoder = codec->getScanlineDecoder(decodeInfo, NULL,
@@ -160,10 +161,103 @@
fPath.c_str(), y-1, (int) result);
}
}
+ canvas->drawBitmap(bitmap, 0, 0);
+ break;
+ }
+ case kScanline_Subset_Mode: {
+ //this mode decodes the image in divisor*divisor subsets, using a scanline decoder
+ const int divisor = 2;
+ const int w = decodeInfo.width();
+ const int h = decodeInfo.height();
+ if (w*h == 1) {
+ return Error::Nonfatal("Subset decoding not supported.");
+ }
+ if (divisor > w || divisor > h) {
+ return SkStringPrintf("divisor %d is too big for %s with dimensions (%d x %d)",
+ divisor, fPath.c_str(), w, h);
+ }
+ const int subsetWidth = w/divisor;
+ const int subsetHeight = h/divisor;
+ // One of our subsets will be larger to contain any pixels that do not divide evenly.
+ const int extraX = w % divisor;
+ const int extraY = h % divisor;
+ /*
+ * if w or h are not evenly divided by divisor need to adjust width and height of end
+ * subsets to cover entire image.
+ * Add extraX and extraY to largestSubsetBm's width and height to adjust width
+ * and height of end subsets.
+ * subsetBm is extracted from largestSubsetBm.
+ * subsetBm's size is determined based on the current subset and may be larger for end
+ * subsets.
+ */
+ SkImageInfo largestSubsetDecodeInfo =
+ decodeInfo.makeWH(subsetWidth + extraX, subsetHeight + extraY);
+ SkBitmap largestSubsetBm;
+ if (!largestSubsetBm.tryAllocPixels(largestSubsetDecodeInfo, NULL, colorTable.get())) {
+ return SkStringPrintf("Image(%s) is too large (%d x %d)\n", fPath.c_str(),
+ largestSubsetDecodeInfo.width(), largestSubsetDecodeInfo.height());
+ }
+ char* line = SkNEW_ARRAY(char, decodeInfo.minRowBytes());
+ SkAutoTDeleteArray<char> lineDeleter(line);
+ 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
+ SkScanlineDecoder* subsetScanlineDecoder = codec->getScanlineDecoder(decodeInfo,
+ NULL, colorPtr, colorCountPtr);
+ if (NULL == subsetScanlineDecoder) {
+ if (x == 0 && y == 0) {
+ //first try, image may not be compatible
+ return Error::Nonfatal("Cannot use scanline decoder for all images");
+ } else {
+ return "Error scanline decoder is NULL";
+ }
+ }
+ //skip to first line of subset
+ const SkImageGenerator::Result skipResult =
+ subsetScanlineDecoder->skipScanlines(y);
+ switch (skipResult) {
+ case SkImageGenerator::kSuccess:
+ case SkImageGenerator::kIncompleteInput:
+ break;
+ default:
+ return SkStringPrintf("%s failed after attempting to skip %d scanlines"
+ "with error message %d", fPath.c_str(), y, (int) skipResult);
+ }
+ //create and set size of subsetBm
+ SkBitmap subsetBm;
+ SkIRect bounds = SkIRect::MakeWH(subsetWidth, subsetHeight);
+ bounds.setXYWH(0, 0, currentSubsetWidth, currentSubsetHeight);
+ SkAssertResult(largestSubsetBm.extractSubset(&subsetBm, bounds));
+ SkAutoLockPixels autlockSubsetBm(subsetBm, true);
+ for (int subsetY = 0; subsetY < currentSubsetHeight; ++subsetY) {
+ const SkImageGenerator::Result subsetResult =
+ subsetScanlineDecoder->getScanlines(line, 1, 0);
+ const size_t bpp = decodeInfo.bytesPerPixel();
+ //copy section of line based on x value
+ memcpy(subsetBm.getAddr(0, subsetY), line + x*bpp, currentSubsetWidth*bpp);
+ switch (subsetResult) {
+ case SkImageGenerator::kSuccess:
+ case SkImageGenerator::kIncompleteInput:
+ break;
+ default:
+ return SkStringPrintf("%s failed after %d scanlines with error"
+ "message %d", fPath.c_str(), y-1, (int) subsetResult);
+ }
+ }
+ canvas->drawBitmap(subsetBm, SkIntToScalar(x), SkIntToScalar(y));
+ }
+ }
break;
}
}
- canvas->drawBitmap(bitmap, 0, 0);
return "";
}