Null canvas

Review URL: http://codereview.appspot.com/6117051/

git-svn-id: http://skia.googlecode.com/svn/trunk@4220 2bbb7eff-a529-9590-31e7-b0007b416f81

diff --git a/gyp/utils.gyp b/gyp/utils.gyp
index d2c413e..9b11e59 100644 (file)
--- a/gyp/utils.gyp
+++ b/gyp/utils.gyp
@@ -26,6 +26,7 @@
         '../include/utils/SkMeshUtils.h',
         '../include/utils/SkNinePatch.h',
         '../include/utils/SkNWayCanvas.h',
+        '../include/utils/SkNullCanvas.h',
         '../include/utils/SkParse.h',
         '../include/utils/SkParsePaint.h',
         '../include/utils/SkParsePath.h',
@@ -50,6 +51,7 @@
         '../src/utils/SkMeshUtils.cpp',
         '../src/utils/SkNinePatch.cpp',
         '../src/utils/SkNWayCanvas.cpp',
+        '../src/utils/SkNullCanvas.cpp',
         '../src/utils/SkOSFile.cpp',
         '../src/utils/SkParse.cpp',
         '../src/utils/SkParseColor.cpp',

diff --git a/include/utils/SkNullCanvas.h b/include/utils/SkNullCanvas.h
new file mode 100644 (file)
index 0000000..62a9edd
--- /dev/null
+++ b/include/utils/SkNullCanvas.h
@@ -0,0 +1,20 @@
+/*
+ * Copyright 2012 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef SkNullCanvas_DEFINED
+#define SkNullCanvas_DEFINED
+
+#include "SkBitmap.h"
+
+class SkCanvas;
+
+/**
+ * Creates a canvas that draws nothing. This is useful for performance testing.
+ */
+SkCanvas* SkCreateNullCanvas();
+
+#endif

diff --git a/src/utils/SkNullCanvas.cpp b/src/utils/SkNullCanvas.cpp
new file mode 100644 (file)
index 0000000..2dc448f
--- /dev/null
+++ b/src/utils/SkNullCanvas.cpp
@@ -0,0 +1,18 @@
+/*
+ * Copyright 2012 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "SkNullCanvas.h"
+
+#include "SkCanvas.h"
+#include "SKNWayCanvas.h"
+
+
+SkCanvas* SkCreateNullCanvas() {
+    // An N-Way canvas forwards calls to N canvas's. When N == 0 it's
+    // effectively a null canvas.
+    return SkNEW(SkNWayCanvas);
+}