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Unified Diff: dm/DMSrcSink.cpp

Issue 1240143002: Add the ability to decode a subset to SkCodec. (Closed) Base URL: https://skia.googlesource.com/skia.git@master
Patch Set: Fix line endings Created 5 years, 5 months ago
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Index: dm/DMSrcSink.cpp
diff --git a/dm/DMSrcSink.cpp b/dm/DMSrcSink.cpp
index 38597b6946994c06d8cc24971dc018163ff41b14..7f553c9ad35c3bb126a61c69fe58afcdcbb9ffc3 100644
--- a/dm/DMSrcSink.cpp
+++ b/dm/DMSrcSink.cpp
@@ -355,6 +355,70 @@ Error CodecSrc::draw(SkCanvas* canvas) const {
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) {
+ return Error::Nonfatal(SkStringPrintf("Cannot codec subset: divisor %d is too big "
+ "for %s with dimensions (%d x %d)", divisor,
+ fPath.c_str(), W, H));
+ }
+ // subset dimensions
+ // SkWebpCodec, the only one that supports subsets, requires even top/left boundaries.
+ const int w = SkAlign2(W / divisor);
+ const int h = SkAlign2(H / divisor);
+ SkCodec::Options opts;
+ SkBitmap subsetBm;
+ // We will reuse pixel memory from bitmap.
+ void* pixels = bitmap.getPixels();
+ // Keep track of left and top (for drawing subsetBm into canvas). We could use
+ // fScale * x and fScale * y, but we want integers such that the next subset will start
+ // where the last one ended. So we'll add decodeInfo.width() and height().
+ int left = 0;
+ for (int x = 0; x < W; x += w) {
+ int top = 0;
+ for (int y = 0; y < H; y+= h) {
+ // Do not make the subset go off the edge of the image.
+ decodeInfo = decodeInfo.makeWH(SkTMin(w, W - x), SkTMin(h, H - y));
+ opts.fSubset.setXYWH(x, y, decodeInfo.width(), decodeInfo.height());
+ // And scale
+ decodeInfo = decodeInfo.makeWH(decodeInfo.width() * fScale,
emmaleer 2015/07/17 22:31:05 You could only call decodeInfo.makeWH() once inste
scroggo 2015/07/20 14:25:42 SkImageInfo::makeWH() is likely pretty cheap (func
+ decodeInfo.height() * fScale);
+ size_t rowBytes = decodeInfo.minRowBytes();
+ if (!subsetBm.installPixels(decodeInfo, pixels, rowBytes, colorTable.get(),
+ NULL, NULL)) {
+ return SkStringPrintf("could not install pixels for %s.", fPath.c_str());
+ }
+ const SkCodec::Result result = codec->getPixels(decodeInfo, pixels, rowBytes,
+ &opts, colorPtr, colorCountPtr);
+ switch (result) {
+ case SkCodec::kSuccess:
+ break;
emmaleer 2015/07/17 22:31:05 What about the case SkCodec::kIncompleteInput. All
scroggo 2015/07/20 14:25:42 I think this goes back to my general concern about
+ case SkCodec::kUnimplemented:
+ if (0 == (x|y)) {
+ // First subset is okay to return unimplemented.
+ return Error::Nonfatal("subset codec not supported");
+ }
+ // If the first subset succeeded, why would a later one fail?
+ // fall through to failure
+ default:
+ return SkStringPrintf("subset codec failed to decode (%d, %d, %d, %d) "
+ "from %s with dimensions (%d x %d)\t error %d",
+ x, y, decodeInfo.width(), decodeInfo.height(),
+ fPath.c_str(), W, H, result);
+ }
+ canvas->drawBitmap(subsetBm, left, top);
+ // translate by the scaled height.
+ top += decodeInfo.height();
+ }
+ // translate by the scaled width.
+ left += decodeInfo.width();
+ }
+ return "";
+ }
}
return "";
}

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