Add HardStopGradientBench_ScaleNumHardStops.cpp

bench/HardStopGradientBench_ScaleNumHardStops.cpp

Index: bench/HardStopGradientBench_ScaleNumHardStops.cpp
diff --git a/bench/HardStopGradientBench_ScaleNumHardStops.cpp b/bench/HardStopGradientBench_ScaleNumHardStops.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..fabb3b0121ea33d79aa87e408b89cd7488bdbf33
--- /dev/null
+++ b/bench/HardStopGradientBench_ScaleNumHardStops.cpp
@@ -0,0 +1,104 @@
+/*
+ * 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"
+
+class HardStopGradientBench_ScaleNumHardStops : public Benchmark {
+public:
+    HardStopGradientBench_ScaleNumHardStops(int colorCount, int hardStopCount) {
+        SkASSERT(hardStopCount <= colorCount);
+
+        fName.printf("hardstop_scale_num_hard_stops_%03d_colors_%03d_hard_stops", 
+                     colorCount, hardStopCount);
+
+        fColorCount    = colorCount;
+        fHardStopCount = hardStopCount;
+    }
+
+    const char* onGetName() override {
+        return fName.c_str();
+    }
+
+    SkIPoint onGetSize() override {
+        return SkIPoint::Make(kSize, kSize);
+    }
+
+    void onPreDraw(SkCanvas* canvas) override {
+        // Left to right
+        SkPoint points[2] = {
+            SkPoint::Make(0,        kSize/2), 
+            SkPoint::Make(kSize-1,  kSize/2),
+        };
+
+        // "Evenly spaced" colors
+        SkAutoTArray<SkColor> colors(fColorCount);
+        for (int i = 0; i < fColorCount; i++) {
+            colors[i] = i * (0xffffffff / fColorCount);
+        }
+
+        // Create requisite number of hard stops, and evenly
+        // space positions after that
+        SkAutoTArray<SkScalar> positions(fColorCount);
+        int k = 0;
+        for (int i = 0; i < fHardStopCount; i++) {
+            positions[k++] = 0.0f;

[tomhudson, 2016/07/26 13:25:14]

This is not right; it looks like you're creating one stop of multiplicity
fHardStopCount, so with a parameter of 1 you'd be creating a soft stop?

+        }
+        for (int i = k; i < fColorCount; i++) {
+            positions[i] = i / (fColorCount - 1.0f);
+        } 
+
+        fPaint.setShader(SkGradientShader::MakeLinear(points,
+                                                      colors.get(),
+                                                      positions.get(),
+                                                      fColorCount,
+                                                      SkShader::TileMode::kClamp_TileMode,
+                                                      0,
+                                                      nullptr));
+    }
+
+    /*
+     * Draw simple linear gradient from left to right
+     */
+    void onDraw(int loops, SkCanvas* canvas) override {
+        for (int i = 0; i < loops; i++) {
+            canvas->drawPaint(fPaint);
+        }
+    }
+
+private:
+    static const int kSize = 500;
+
+    SkString fName;
+    int      fColorCount;
+    int      fHardStopCount;
+    SkPaint  fPaint;
+
+    typedef Benchmark INHERITED;
+};
+
+DEF_BENCH(return new HardStopGradientBench_ScaleNumHardStops(10, 1);)
+DEF_BENCH(return new HardStopGradientBench_ScaleNumHardStops(10, 2);)
+DEF_BENCH(return new HardStopGradientBench_ScaleNumHardStops(10, 5);)
+
+DEF_BENCH(return new HardStopGradientBench_ScaleNumHardStops(20,  1);)
+DEF_BENCH(return new HardStopGradientBench_ScaleNumHardStops(20,  5);)
+DEF_BENCH(return new HardStopGradientBench_ScaleNumHardStops(20, 10);)
+
+DEF_BENCH(return new HardStopGradientBench_ScaleNumHardStops(50,  1);)
+DEF_BENCH(return new HardStopGradientBench_ScaleNumHardStops(50, 10);)
+DEF_BENCH(return new HardStopGradientBench_ScaleNumHardStops(50, 25);)
+
+DEF_BENCH(return new HardStopGradientBench_ScaleNumHardStops(100,  1);)
+DEF_BENCH(return new HardStopGradientBench_ScaleNumHardStops(100, 25);)
+DEF_BENCH(return new HardStopGradientBench_ScaleNumHardStops(100, 50);)