alpha threshold bitmap shader
Committed: http://code.google.com/p/skia/source/detail?r=11122
R=reed@google.com
Author: bsalomon@google.com
Review URL: https://chromiumcodereview.appspot.com/23707019
git-svn-id: http://skia.googlecode.com/svn/trunk@11131 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/include/effects/SkBitmapAlphaThresholdShader.h b/include/effects/SkBitmapAlphaThresholdShader.h
new file mode 100644
index 0000000..61596da
--- /dev/null
+++ b/include/effects/SkBitmapAlphaThresholdShader.h
@@ -0,0 +1,24 @@
+/*
+ * 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 "SkShader.h"
+#include "SkBitmap.h"
+#include "SkRegion.h"
+#include "SkString.h"
+
+class SK_API SkBitmapAlphaThresholdShader : public SkShader {
+public:
+ /**
+ * Creates a shader that samples a bitmap and a region. If the sample is inside the region
+ * the alpha of the bitmap color is boosted up to a threshold value. If it is
+ * outside the region then the bitmap alpha is decreased to the threshold value.
+ * The 0,0 point of the region corresponds to the upper left corner of the bitmap
+ * Currently, this only has a GPU implementation, doesn't respect the paint's bitmap
+ * filter setting, and always uses clamp mode.
+ */
+ static SkShader* Create(const SkBitmap& bitmap, const SkRegion& region, U8CPU threshold);
+};