Benchmark designed to exercise fractional image scale/translation

bench/BitmapFractionalBench.cpp

Index: bench/BitmapFractionalBench.cpp
diff --git a/bench/BitmapFractionalBench.cpp b/bench/BitmapFractionalBench.cpp
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+++ b/bench/BitmapFractionalBench.cpp
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+/*
+ * Copyright 2013 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 "SkBlurMask.h"
+#include "SkCanvas.h"
+#include "SkPaint.h"
+#include "SkRandom.h"
+#include "SkShader.h"
+#include "SkString.h"
+
+class BitmapFractionalBench: public Benchmark {
+    int                  fInputSize;
+    int                  fOutputSize;
+    SkPaint::FilterLevel fFilterLevel;
+    SkString             fName;
+
+public:
+    BitmapFractionalBench( int is, const char *name, SkPaint::FilterLevel filterLevel )  {
+        fInputSize = is;
+        fOutputSize = 2*is;
+        fFilterLevel = filterLevel;
+        fName.printf( "bitmap_fractional_bench_%s", name );
+    }
+
+protected:
+
+    SkBitmap fInputBitmap, fOutputBitmap;
+    SkMatrix fMatrix;
+
+    virtual const char* onGetName() {
+        return fName.c_str();
+    }
+
+    int inputSize() const {
+        return fInputSize;
+    }
+
+    int outputSize() const {
+        return fOutputSize;
+    }
+
+    SkIPoint onGetSize() SK_OVERRIDE {
+        return SkIPoint::Make( fOutputSize, fOutputSize );
+    }
+
+    virtual void onPreDraw() {
+        fInputBitmap.allocN32Pixels(fInputSize, fInputSize, true);
+        fInputBitmap.eraseColor(SK_ColorWHITE);
+
+        fOutputBitmap.allocN32Pixels(fOutputSize, fOutputSize, true);
+    }
+
+    virtual void onDraw(const int loops, SkCanvas*) {
+        SkPaint paint;
+        this->setupPaint(&paint);
+
+        preBenchSetup();
+
+        SkCanvas canvas( fOutputBitmap );
+        paint.setFilterLevel(fFilterLevel);
+        fInputBitmap.notifyPixelsChanged();
+
+        for (int i = 0; i < loops; i++) {
+            // up-scale the image by a variety of close, fractional scales
+            for (int j = 0 ; j < 20 ; j++) {
+                fMatrix = SkMatrix::I();
+                fMatrix.setScale( 1 + j/500.f, 1 + j/500.f );
+                canvas.drawBitmapMatrix( fInputBitmap, fMatrix, &paint );
+            }
+            // down-scale the image by a variety of close, fractional scales
+            for (int j = 0 ; j < 20 ; j++) {
+                fMatrix = SkMatrix::I();
+                fMatrix.setScale( 1 - j/500.f, 1 - j/500.f );
+                canvas.drawBitmapMatrix( fInputBitmap, fMatrix, &paint );
+            }
+            // Now try some fractional translates
+            for (int j = 0 ; j < 20 ; j++) {
+                fMatrix = SkMatrix::I();
+                fMatrix.setTranslate( j/3.f, j/3.f );
+                canvas.drawBitmapMatrix( fInputBitmap, fMatrix, &paint );
+            }
+            // Finally, some fractional translates with non-identity scale.
+            for (int j = 0 ; j < 20 ; j++) {
+                fMatrix = SkMatrix::I();
+                fMatrix.setTranslate( j/3.f, j/3.f );
+                fMatrix.preScale( 1.5f, 1.5f );
+                canvas.drawBitmapMatrix( fInputBitmap, fMatrix, &paint );
+            }
+        }
+    }
+
+    virtual void preBenchSetup() {}
+private:
+    typedef Benchmark INHERITED;
+};
+
+DEF_BENCH(return new BitmapFractionalBench(256, "high", SkPaint::kHigh_FilterLevel);)
+DEF_BENCH(return new BitmapFractionalBench(256, "medium", SkPaint::kMedium_FilterLevel);)
+DEF_BENCH(return new BitmapFractionalBench(256, "low", SkPaint::kLow_FilterLevel);)