Factor out checkerboard function in gm and sampleapp into tools.

Review URL: https://codereview.chromium.org/834303005

2 files changed, 62 insertions, 0 deletions

diff --git a/tools/Checkerboard.cpp b/tools/Checkerboard.cpp
new file mode 100644
index 0000000000..80de125f15
--- /dev/null
+++ b/tools/Checkerboard.cpp
@@ -0,0 +1,28 @@
+/*
+ * Copyright 2015 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 "SkCanvas.h"
+#include "SkShader.h"
+
+SkShader* sk_tools::CreateCheckerboardShader(
+        SkColor c1, SkColor c2, int size) {
+    SkBitmap bm;
+    bm.allocN32Pixels(2 * size, 2 * size);
+    bm.eraseColor(c1);
+    bm.eraseArea(SkIRect::MakeLTRB(0, 0, size, size), c2);
+    bm.eraseArea(SkIRect::MakeLTRB(size, size, 2 * size, 2 * size), c2);
+    return SkShader::CreateBitmapShader(
+            bm, SkShader::kRepeat_TileMode, SkShader::kRepeat_TileMode);
+}
+
+void sk_tools::DrawCheckerboard(SkCanvas* canvas,
+                                    SkColor c1, SkColor c2, int size) {
+    SkPaint paint;
+    paint.setShader(CreateCheckerboardShader(c1, c2, size))->unref();
+    canvas->drawPaint(paint);
+}
diff --git a/tools/Checkerboard.h b/tools/Checkerboard.h
new file mode 100644
index 0000000000..b81e43616f
--- /dev/null
+++ b/tools/Checkerboard.h
@@ -0,0 +1,34 @@
+/*
+ * Copyright 2015 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+#ifndef Checkerboard_DEFINED
+#define Checkerboard_DEFINED
+
+#include "SkColor.h"
+
+class SkCanvas;
+class SkShader;
+
+namespace sk_tools {
+
+/** Returns a newly created CheckerboardShader. */
+SkShader* CreateCheckerboardShader(SkColor c1, SkColor c2, int size);
+
+/** Draw a checkerboard pattern in the current canvas, restricted to
+    the current clip. */
+void DrawCheckerboard(SkCanvas* canvas,
+                      SkColor color1,
+                      SkColor color2,
+                      int size);
+
+/** A default checkerboard. */
+inline void DrawCheckerboard(SkCanvas* canvas) {
+    sk_tools::DrawCheckerboard(canvas, 0xFF999999, 0xFF666666, 8);
+}
+
+}  // namespace sk_tools
+
+#endif  // Checkerboard_DEFINED