Improved subset benchmarks

I think these changes to the subset benchmarks cover what we discussed yesterday.

I removed the divisor benchmarks (2x2, 3x3) and changed the single subset benchmarks.

Also, we will no longer benchmark subset decodes on small images.

BUG=skia:

Review URL: https://codereview.chromium.org/1188223002

3 files changed, 24 insertions, 188 deletions

diff --git a/bench/nanobench.cpp b/bench/nanobench.cpp
index b2b36fa6c7..65d9216e35 100644
--- a/bench/nanobench.cpp
+++ b/bench/nanobench.cpp
@@ -20,7 +20,6 @@
 #include "SKPAnimationBench.h"
 #include "SKPBench.h"
 #include "SubsetBenchPriv.h"
-#include "SubsetDivisorBench.h"
 #include "SubsetSingleBench.h"
 #include "SubsetTranslateBench.h"
 #include "SubsetZoomBench.h"
@@ -496,6 +495,7 @@ static bool valid_subset_bench(const SkString& path, SkColorType colorType, bool
     SkAutoTUnref<SkData> encoded(SkData::NewFromFileName(path.c_str()));
     SkAutoTDelete<SkMemoryStream> stream(new SkMemoryStream(encoded));
 
+    // Check that we can create a codec or image decoder.
     if (useCodec) {
         SkAutoTDelete<SkCodec> codec(SkCodec::NewFromStream(stream.detach()));
         if (NULL == codec) {
@@ -535,6 +535,13 @@ static bool valid_subset_bench(const SkString& path, SkColorType colorType, bool
             return false;
         }
     }
+
+    // Check if the image is large enough for a meaningful subset benchmark.
+    if (*width <= 512 && *height <= 512) {
+        // This should not print a message since it is not an error.
+        return false;
+    }
+
     return true;
 }
 
@@ -812,21 +819,20 @@ public:
                         if (valid_subset_bench(path, colorType, useCodec, &width, &height)) {
                             switch (currentSubsetType) {
                                 case kTopLeft_SubsetType:
-                                    return new SubsetSingleBench(path, colorType, width/2,
-                                            height/2, 0, 0, useCodec);
+                                    return new SubsetSingleBench(path, colorType, width/3,
+                                            height/3, 0, 0, useCodec);
                                 case kTopRight_SubsetType:
-                                    return new SubsetSingleBench(path, colorType, width/2,
-                                            height/2, width/2, 0, useCodec);
+                                    return new SubsetSingleBench(path, colorType, width/3,
+                                            height/3, 2*width/3, 0, useCodec);
+                                case kMiddle_SubsetType:
+                                    return new SubsetSingleBench(path, colorType, width/3,
+                                            height/3, width/3, height/3, useCodec);
                                 case kBottomLeft_SubsetType:
-                                    return new SubsetSingleBench(path, colorType, width/2,
-                                            height/2, 0, height/2, useCodec);
+                                    return new SubsetSingleBench(path, colorType, width/3,
+                                            height/3, 0, 2*height/3, useCodec);
                                 case kBottomRight_SubsetType:
-                                    return new SubsetSingleBench(path, colorType, width/2,
-                                            height/2, width/2, height/2, useCodec);
-                                case k2x2_SubsetType:
-                                    return new SubsetDivisorBench(path, colorType, 2, useCodec);
-                                case k3x3_SubsetType:
-                                    return new SubsetDivisorBench(path, colorType, 3, useCodec);
+                                    return new SubsetSingleBench(path, colorType, width/3,
+                                            height/3, 2*width/3, 2*height/3, useCodec);
                                 case kTranslate_SubsetType:
                                     return new SubsetTranslateBench(path, colorType, 512, 512,
                                             useCodec);
@@ -874,12 +880,11 @@ private:
     enum SubsetType {
         kTopLeft_SubsetType     = 0,
         kTopRight_SubsetType    = 1,
-        kBottomLeft_SubsetType  = 2,
-        kBottomRight_SubsetType = 3,
-        k2x2_SubsetType         = 4,
-        k3x3_SubsetType         = 5,
-        kTranslate_SubsetType   = 6,
-        kZoom_SubsetType        = 7,
+        kMiddle_SubsetType      = 2,
+        kBottomLeft_SubsetType  = 3,
+        kBottomRight_SubsetType = 4,
+        kTranslate_SubsetType   = 5,
+        kZoom_SubsetType        = 6,
         kLast_SubsetType        = kZoom_SubsetType
     };
 
diff --git a/bench/subset/SubsetDivisorBench.cpp b/bench/subset/SubsetDivisorBench.cpp
deleted file mode 100644
index 0ec2579b6d..0000000000
--- a/bench/subset/SubsetDivisorBench.cpp
+++ /dev/null
@@ -1,129 +0,0 @@
-/*
- * 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) {
-    // When the color type is kIndex8, we will need to store the color table.  If it is
-    // used, it will be initialized by the codec.
-    int colorCount;
-    SkPMColor colors[256];
-    if (fUseCodec) {
-        for (int count = 0; count < n; count++) {
-            SkAutoTDelete<SkCodec> codec(SkCodec::NewFromStream(fStream->duplicate()));
-            const SkImageInfo info = codec->getInfo().makeColorType(fColorType);
-            SkAutoTDeleteArray<uint8_t> row(SkNEW_ARRAY(uint8_t, info.minRowBytes()));
-            SkScanlineDecoder* scanlineDecoder = codec->getScanlineDecoder(
-                    info, NULL, colors, &colorCount);
-
-            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 {
-        // We create a color table here to satisfy allocPixels() when the output
-        // type is kIndex8.  It's okay that this is uninitialized since we never
-        // use it.
-        SkColorTable* colorTable = SkNEW_ARGS(SkColorTable, (colors, 0));
-        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.
-            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);
-                }
-            }
-        }
-    }
-}
diff --git a/bench/subset/SubsetDivisorBench.h b/bench/subset/SubsetDivisorBench.h
deleted file mode 100644
index e5ea71ff51..0000000000
--- a/bench/subset/SubsetDivisorBench.h
+++ /dev/null
@@ -1,40 +0,0 @@
-/*
- * 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 "Benchmark.h"
-#include "SkImageDecoder.h"
-#include "SkImageInfo.h"
-#include "SkStream.h"
-#include "SkString.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.
- *
- */
-class SubsetDivisorBench : public Benchmark {
-public:
-
-    SubsetDivisorBench(const SkString& path,
-                       SkColorType colorType,
-                       uint32_t divisor,
-                       bool useCodec);
-
-protected:
-    const char* onGetName() override;
-    bool isSuitableFor(Backend backend) override;
-    void onDraw(const int n, SkCanvas* canvas) override;
-
-private:
-    SkString                      fName;
-    SkColorType                   fColorType;
-    const uint32_t                fDivisor;
-    const bool                    fUseCodec;
-    SkAutoTDelete<SkMemoryStream> fStream;
-    typedef Benchmark INHERITED;
-};