Factor out checkerboard function in gm and sampleapp into tools.

gm/imagefiltersscaled.cpp

 /*
  * Copyright 2014 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
+#include "checkerboard.h"
 #include "gm.h"
 #include "SkColor.h"
 #include "SkBitmapSource.h"
 #include "SkBlurImageFilter.h"
 #include "SkDisplacementMapEffect.h"
 #include "SkDropShadowImageFilter.h"
 #include "SkGradientShader.h"
 #include "SkLightingImageFilter.h"
 #include "SkMorphologyImageFilter.h"
 #include "SkOffsetImageFilter.h"
@@ skipping 18 matching lines @@
     }
 
     virtual SkString onShortName() {
         return SkString("imagefiltersscaled");
     }
 
     virtual SkISize onISize() {
         return SkISize::Make(1428, 500);
     }
 
-    void make_checkerboard() {
-        fCheckerboard.allocN32Pixels(64, 64);
-        SkCanvas canvas(fCheckerboard);
-        canvas.clear(0x00000000);
-        SkPaint darkPaint;
-        darkPaint.setColor(0xFF404040);
-        SkPaint lightPaint;
-        lightPaint.setColor(0xFFA0A0A0);
-        for (int y = 0; y < 64; y += 16) {
-          for (int x = 0; x < 64; x += 16) {
-            canvas.save();
-            canvas.translate(SkIntToScalar(x), SkIntToScalar(y));
-            canvas.drawRect(SkRect::MakeXYWH(0, 0, 8, 8), darkPaint);
-            canvas.drawRect(SkRect::MakeXYWH(8, 0, 8, 8), lightPaint);
-            canvas.drawRect(SkRect::MakeXYWH(0, 8, 8, 8), lightPaint);
-            canvas.drawRect(SkRect::MakeXYWH(8, 8, 8, 8), darkPaint);
-            canvas.restore();
-          }
-        }
-    }
-
     void make_gradient_circle(int width, int height) {
         SkScalar x = SkIntToScalar(width / 2);
         SkScalar y = SkIntToScalar(height / 2);
         SkScalar radius = SkScalarMul(SkMinScalar(x, y), SkIntToScalar(4) / SkIntToScalar(5));
         fGradientCircle.allocN32Pixels(width, height);
         SkCanvas canvas(fGradientCircle);
         canvas.clear(0x00000000);
         SkColor colors[2];
         colors[0] = SK_ColorWHITE;
         colors[1] = SK_ColorBLACK;
         SkAutoTUnref<SkShader> shader(
             SkGradientShader::CreateRadial(SkPoint::Make(x, y), radius, colors, NULL, 2,
                                            SkShader::kClamp_TileMode)
         );
         SkPaint paint;
         paint.setShader(shader);
         canvas.drawCircle(x, y, radius, paint);
     }
 
     virtual void onDraw(SkCanvas* canvas) {
         if (!fInitialized) {
-            this->make_checkerboard();
+            fCheckerboard.allocN32Pixels(64, 64);
+            SkCanvas checkerboardCanvas(fCheckerboard);
+            skiagm::Checkerboard(&checkerboardCanvas, 0xFFA0A0A0, 0xFF404040);
+
             this->make_gradient_circle(64, 64);
             fInitialized = true;
         }
         canvas->clear(0x00000000);
 
         SkAutoTUnref<SkImageFilter> gradient(SkBitmapSource::Create(fGradientCircle));
         SkAutoTUnref<SkImageFilter> checkerboard(SkBitmapSource::Create(fCheckerboard));
         SkAutoTUnref<SkShader> noise(SkPerlinNoiseShader::CreateFractalNoise(
             SkDoubleToScalar(0.1), SkDoubleToScalar(0.05), 1, 0));
 
@@ skipping 76 matching lines @@
     SkBitmap fGradientCircle;
     typedef GM INHERITED;
 };
 
 //////////////////////////////////////////////////////////////////////////////
 
 static GM* MyFactory(void*) { return new ImageFiltersScaledGM; }
 static GMRegistry reg(MyFactory);
 
 }