Subset decoding benchmarks

bench/subset/SubsetDivisorBench.cpp

Index: bench/subset/SubsetDivisorBench.cpp
diff --git a/bench/subset/SubsetDivisorBench.cpp b/bench/subset/SubsetDivisorBench.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..6ed281ed3c6911f99341909566a8118aa5c3fa2c
--- /dev/null
+++ b/bench/subset/SubsetDivisorBench.cpp
@@ -0,0 +1,123 @@
+/*
+ * 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 "SubsetDivisorBench.h"
+#include "SubsetBenchPriv.h"
+#include "SkData.h"
+#include "SkCodec.h"
+#include "SkImageDecoder.h"
+#include "SkOSFile.h"
+#include "SkStream.h"
+
+/*
+ *
+ * This benchmark is designed to test the performance of subset decoding.
+ * It uses a divisor to decode the entire image in a grid of divisor x divisor blocks.
+ *
+ */
+
+SubsetDivisorBench::SubsetDivisorBench(const SkString& path,
+                                       SkColorType colorType,
+                                       uint32_t divisor,
+                                       bool useCodec)
+    : fColorType(colorType)
+    , fDivisor(divisor)
+    , fUseCodec(useCodec)
+{
+    // Parse the filename
+    SkString baseName = SkOSPath::Basename(path.c_str());
+
+    // Choose an informative color name
+    const char* colorName = get_color_name(fColorType);
+
+    fName.printf("%sSubsetDivisor_%dx%d_%s_%s", fUseCodec ? "Codec" : "Image", fDivisor, fDivisor,
+            baseName.c_str(), colorName);
+
+    // Perform the decode setup
+    SkAutoTUnref<SkData> encoded(SkData::NewFromFileName(path.c_str()));
+    fStream.reset(new SkMemoryStream(encoded));
+}
+
+const char* SubsetDivisorBench::onGetName() {
+    return fName.c_str();
+}
+
+bool SubsetDivisorBench::isSuitableFor(Backend backend) {
+    return kNonRendering_Backend == backend;
+}
+
+void SubsetDivisorBench::onDraw(const int n, SkCanvas* canvas) {
+    if (fUseCodec) {
+        for (int count = 0; count < n; count++) {
+            SkAutoTDelete<SkCodec> codec(SkCodec::NewFromStream(fStream->duplicate()));
+            const SkImageInfo info = codec->getInfo();
+            SkAutoTDeleteArray<uint8_t> row(SkNEW_ARRAY(uint8_t, info.minRowBytes()));
+            SkScanlineDecoder* scanlineDecoder =
+                    codec->getScanlineDecoder(info.makeColorType(fColorType));
+
+            const uint32_t subsetWidth = info.width() / fDivisor;
+            const uint32_t subsetHeight = info.height() / fDivisor;
+            const uint32_t maxSubsetWidth = subsetWidth + info.width() % fDivisor;
+            const uint32_t maxSubsetHeight = subsetHeight + info.height() % fDivisor;
+            SkBitmap bitmap;
+            // Note that we use the same bitmap for all of the subsets.
+            // It might be slightly larger than necessary for some of the subsets.
+            bitmap.allocPixels(info.makeWH(maxSubsetWidth, maxSubsetHeight));
+
+            for (uint32_t blockX = 0; blockX < fDivisor; blockX++) {
+                for (uint32_t blockY = 0; blockY < fDivisor; blockY++) {
+                    scanlineDecoder->skipScanlines(blockY * subsetHeight);
+                    const uint32_t currSubsetWidth =
+                            (blockX == fDivisor - 1) ? maxSubsetWidth : subsetWidth;
+                    const uint32_t currSubsetHeight =
+                            (blockY == fDivisor - 1) ? maxSubsetHeight : subsetHeight;
+                    const uint32_t bpp = info.bytesPerPixel();
+                    for (uint32_t y = 0; y < currSubsetHeight; y++) {
+                        scanlineDecoder->getScanlines(row.get(), 1, 0);
+                        memcpy(bitmap.getAddr(0, y), row.get() + blockX * subsetWidth * bpp,
+                                currSubsetWidth * bpp);
+                    }
+                }
+            }
+        }
+    } else {
+        SkPMColor colors[256];
+        SkColorTable* colorTable = SkNEW_ARGS(SkColorTable, (colors, 0));

[scroggo, 2015/06/04 13:50:04]

Maybe add a comment that it's okay for these colors to be uninitialized, since
we never use them - they're only here to satisfy allocPixels.

[msarett, 2015/06/08 16:28:33]

Done.

+        for (int count = 0; count < n; count++) {
+            int width, height;
+            SkAutoTDelete<SkImageDecoder> decoder(SkImageDecoder::Factory(fStream));
+            decoder->buildTileIndex(fStream->duplicate(), &width, &height);
+
+            const uint32_t subsetWidth = width / fDivisor;
+            const uint32_t subsetHeight = height / fDivisor;
+            const uint32_t maxSubsetWidth = subsetWidth + width % fDivisor;
+            const uint32_t maxSubsetHeight = subsetHeight + height % fDivisor;
+            SkBitmap bitmap;
+            // Note that we use the same bitmap for all of the subsets.
+            // It might be slightly larger than necessary for some of the subsets.
+            // If we do not include this step, decodeSubset() would allocate space
+            // for the pixels automatically, but this would not allow us to reuse the
+            // same bitmap as the other subsets.  We want to reuse the same bitmap
+            // because it gives a more fair comparison with SkCodec and is a common
+            // use case of BitmapRegionDecoder.;

[scroggo, 2015/06/04 13:50:04]

Semicolon not needed here.

[msarett, 2015/06/08 16:28:33]

Done.

+            bitmap.allocPixels(SkImageInfo::Make(maxSubsetWidth, maxSubsetHeight,
+                    fColorType, kOpaque_SkAlphaType), NULL, colorTable);
+
+            for (uint32_t blockX = 0; blockX < fDivisor; blockX++) {
+                for (uint32_t blockY = 0; blockY < fDivisor; blockY++) {
+                    const uint32_t currSubsetWidth =
+                            (blockX == fDivisor - 1) ? maxSubsetWidth : subsetWidth;
+                    const uint32_t currSubsetHeight =
+                            (blockY == fDivisor - 1) ? maxSubsetHeight : subsetHeight;
+                    SkIRect rect = SkIRect::MakeXYWH(blockX * subsetWidth,
+                            blockY * subsetHeight, currSubsetWidth, currSubsetHeight);
+                    decoder->decodeSubset(&bitmap, rect, fColorType);
+                }
+            }
+        }
+    }
+}