Add HardStopGradientBench.cpp

bench/HardStopGradientBench.cpp

Index: bench/HardStopGradientBench.cpp
diff --git a/bench/HardStopGradientBench.cpp b/bench/HardStopGradientBench.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..40dd95d891566663c9e3310e6583b4b5b003a476
--- /dev/null
+++ b/bench/HardStopGradientBench.cpp
@@ -0,0 +1,128 @@
+/*
+ * Copyright 2016 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 "SkCanvas.h"
+#include "SkShader.h"
+#include "SkGradientShader.h"
+#include "SkString.h"
+#include "SkColor.h"
+#include "SkPaint.h"
+
+struct GradData {

[bsalomon, 2016/07/07 18:36:32]

Is this used?

+    int             fCount;
+    const SkColor*  fColors;
+    const SkScalar* fPos;
+    const char*     fName;
+};
+
+static constexpr int kMaxCount = 50;
+
+static const char* get_tilemode_name(SkShader::TileMode tilemode) {
+    switch (tilemode) {
+        case SkShader::kClamp_TileMode:
+            return "clamp";
+        case SkShader::kRepeat_TileMode:
+            return "repeat";
+        case SkShader::kMirror_TileMode:
+            return "mirror";
+        default:
+            SkDEBUGFAIL("Unknown tilemode");
+            return "error";
+    }
+}
+
+class HardStopGradientBench : public Benchmark {
+public:
+    HardStopGradientBench(SkShader::TileMode tilemode, int count) {
+        count = std::max(0, std::min(count, kMaxCount));

[bsalomon, 2016/07/07 18:36:32]

Not sure I understand the purpose of kMaxCount.

+
+        fName.printf("hardstop_%s_%02d_colors", get_tilemode_name(tilemode), count);
+
+        fTileMode   = tilemode;
+        fColorCount = count;
+
+        // "Evenly spaced" colors

[bsalomon, 2016/07/07 18:36:32]

Could from here onward and createShaderPaint be done in onPreDraw? nanobench
creates instances of Benchmarks just to get their names and filter them.

Also doesn't seem like you really need to store fPositions and fColors
permanently, just while creating the paint.

+        for (int i = 0; i < count; i++) {
+            fColors[i] = i * (0xffffffff / count);
+        }
+
+        // Create a hard stop
+        fPositions[0] = 0.0f;
+        fPositions[1] = 0.0f;
+        for (int i = 2; i < count; i++) {
+            // Evenly spaced afterwards
+            fPositions[i] = i / (count - 1.0f);
+        }
+    }
+
+    const char* onGetName() override {
+        return fName.c_str();
+    }
+
+    SkIPoint onGetSize() override {
+        return SkIPoint::Make(kSize, kSize);
+    }
+
+    /*
+     * Draw simple linear gradient from left to right
+     */
+    void onDraw(int loops, SkCanvas* canvas) override {
+        SkPoint points[2] = {
+            SkPoint::Make(0,        kSize/2), 
+            SkPoint::Make(kSize-1,  kSize/2),
+        };
+
+        SkPaint paint = this->createShaderPaint(points);
+
+        for (int i = 0; i < loops; i++) {
+            canvas->drawPaint(paint);
+        }
+    }
+
+private:
+    static const int kSize = 500;
+
+    SkShader::TileMode  fTileMode;
+    SkString            fName;
+    int                 fColorCount;
+    SkScalar            fPositions[kMaxCount];
+    SkColor             fColors[kMaxCount];
+
+    SkPaint createShaderPaint(SkPoint points[2]) {
+        SkPaint p;
+        p.setShader(SkGradientShader::MakeLinear(points,
+                                                 fColors,
+                                                 fPositions,
+                                                 fColorCount,
+                                                 fTileMode,
+                                                 0,
+                                                 nullptr));
+        return p;
+    }
+
+    typedef Benchmark INHERITED;
+};
+
+// Clamp
+DEF_BENCH(return new HardStopGradientBench(SkShader::kClamp_TileMode, kMaxCount/10);)
+DEF_BENCH(return new HardStopGradientBench(SkShader::kClamp_TileMode, kMaxCount/5);)
+DEF_BENCH(return new HardStopGradientBench(SkShader::kClamp_TileMode, kMaxCount/2);)
+DEF_BENCH(return new HardStopGradientBench(SkShader::kClamp_TileMode, kMaxCount);)
+
+// Repeat
+DEF_BENCH(return new HardStopGradientBench(SkShader::kRepeat_TileMode, kMaxCount/10);)
+DEF_BENCH(return new HardStopGradientBench(SkShader::kRepeat_TileMode, kMaxCount/5);)
+DEF_BENCH(return new HardStopGradientBench(SkShader::kRepeat_TileMode, kMaxCount/2);)
+DEF_BENCH(return new HardStopGradientBench(SkShader::kRepeat_TileMode, kMaxCount);)
+
+// Mirror
+DEF_BENCH(return new HardStopGradientBench(SkShader::kMirror_TileMode, kMaxCount/10);)
+DEF_BENCH(return new HardStopGradientBench(SkShader::kMirror_TileMode, kMaxCount/5);)
+DEF_BENCH(return new HardStopGradientBench(SkShader::kMirror_TileMode, kMaxCount/2);)
+DEF_BENCH(return new HardStopGradientBench(SkShader::kMirror_TileMode, kMaxCount);)