Factor out checkerboard function in gm and sampleapp into tools.

gm/offsetimagefilter.cpp

 /*
  * 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 "checkerboard.h"
 #include "gm.h"
 #include "SkOffsetImageFilter.h"
 #include "SkBitmapSource.h"
 
 #define WIDTH 600
 #define HEIGHT 100
 #define MARGIN 12
 
 namespace skiagm {
 
@@ skipping 14 matching lines @@
         canvas.clear(0x00000000);
         SkPaint paint;
         paint.setAntiAlias(true);
         sk_tool_utils::set_portable_typeface(&paint);
         paint.setColor(0xD000D000);
         paint.setTextSize(SkIntToScalar(96));
         const char* str = "e";
         canvas.drawText(str, strlen(str), SkIntToScalar(15), SkIntToScalar(65), paint);
     }
 
-    void make_checkerboard() {
-        fCheckerboard.allocN32Pixels(80, 80);
-        SkCanvas canvas(fCheckerboard);
-        canvas.clear(0x00000000);
-        SkPaint darkPaint;
-        darkPaint.setColor(0xFF404040);
-        SkPaint lightPaint;
-        lightPaint.setColor(0xFFA0A0A0);
-        for (int y = 0; y < 80; y += 16) {
-          for (int x = 0; x < 80; 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();
-          }
-        }
-    }
-
     virtual SkISize onISize() {
         return SkISize::Make(WIDTH, HEIGHT);
     }
 
     void drawClippedBitmap(SkCanvas* canvas, const SkBitmap& bitmap, const SkPaint& paint, SkScalar scale, const SkIRect& cropRect) {
         canvas->save();
         SkRect clipRect = SkRect::MakeWH(
             SkIntToScalar(bitmap.width()), SkIntToScalar(bitmap.height()));
         canvas->clipRect(clipRect);
         canvas->scale(scale, scale);
         canvas->drawBitmap(bitmap, 0, 0, &paint);
         canvas->restore();
         SkPaint strokePaint;
         strokePaint.setStyle(SkPaint::kStroke_Style);
         strokePaint.setColor(SK_ColorRED);
 
         // Draw a boundary rect around the intersection of the clip rect
         // and crop rect.
         SkMatrix scaleMatrix;
         scaleMatrix.setScale(scale, scale);
         SkRect cropRectFloat;
         scaleMatrix.mapRect(&cropRectFloat, SkRect::Make(cropRect));
         clipRect.intersect(cropRectFloat);
         canvas->drawRect(clipRect, strokePaint);
     }
 
     virtual void onDraw(SkCanvas* canvas) {
         if (!fInitialized) {
             make_bitmap();
-            make_checkerboard();
+
+            fCheckerboard.allocN32Pixels(80, 80);
+            SkCanvas checkerboardCanvas(fCheckerboard);
+            skiagm::Checkerboard(&checkerboardCanvas, 0xFFA0A0A0, 0xFF404040);
+
             fInitialized = true;
         }
         canvas->clear(0x00000000);
         SkPaint paint;
 
         for (int i = 0; i < 4; i++) {
             SkBitmap* bitmap = (i & 0x01) ? &fCheckerboard : &fBitmap;
             SkIRect cropRect = SkIRect::MakeXYWH(i * 12,
                                                  i * 8,
                                                  bitmap->width() - i * 8,
@@ skipping 21 matching lines @@
     SkBitmap fBitmap, fCheckerboard;
     bool fInitialized;
 };
 
 //////////////////////////////////////////////////////////////////////////////
 
 static GM* MyFactory(void*) { return new OffsetImageFilterGM; }
 static GMRegistry reg(MyFactory);
 
 }