Subset decoding benchmarks

bench/SubsetDivisorBench.h

+/*
+ * 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 {

[scroggo, 2015/06/01 17:25:15]

I remember you were concerned about having so many different classes/files.
Maybe we should put all of these in a folder inside bench? (Although maybe hold
off on that so it's easier to see the changes across revisions in the reitveld
code review tool... If we decide we want them in their own folder, you can do
the move as its own patch set, either now or once we're happy with them.)

[msarett, 2015/06/01 20:37:02]

I will move them immediately after the next upload.

+public:
+
+    static SubsetDivisorBench* Create(SkString* path,

[scroggo, 2015/06/01 17:25:14]

Why does this take a pointer to a path? Why not a const ref?

(Typically we use a pointer one of the following is true:

A. the function will modify the object
B. the pointer can be NULL

Neither appears to be the case here.)

[msarett, 2015/06/01 20:37:02]

Agreed.  There is not a good reason for this to be a pointer.

+                                      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:
+
+    SubsetDivisorBench(SkString* stream,
+                       SkColorType colorType,
+                       uint32_t divisor,
+                       bool useCodec);
+
+
+    SkString fName;

[scroggo, 2015/06/01 17:25:14]

style nit: typically we line up the names of member variables. e.g.

SkString    fName;
SkColorType fColorType;

etc.

[msarett, 2015/06/01 20:37:02]

Done.

+    SkColorType fColorType;
+    const uint32_t fDivisor;
+    const bool fUseCodec;
+    SkAutoTDelete<SkMemoryStream> fStream;
+    typedef Benchmark INHERITED;
+};