add gamma maskfilter, especially nice when applied after a blur

git-svn-id: http://skia.googlecode.com/svn/trunk@411 2bbb7eff-a529-9590-31e7-b0007b416f81

1 files changed, 58 insertions, 0 deletions

diff --git a/include/effects/SkGammaMaskFilter.h b/include/effects/SkGammaMaskFilter.h
new file mode 100644
index 0000000000..fdff43d1e8
--- /dev/null
+++ b/include/effects/SkGammaMaskFilter.h
@@ -0,0 +1,58 @@
+/*
+ * Copyright (C) 2006 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef SkGammaMaskFilter_DEFINED
+#define SkGammaMaskFilter_DEFINED
+
+#include "SkMaskFilter.h"
+#include "SkScalar.h"
+
+/** \class SkGammaMaskFilter
+ 
+    Applies a table lookup on each of the alpha values in the mask.
+    An arbitrary table can be assigned, or a gamma (pow) table is computed
+    based on the specified exponent.
+ */
+class SkGammaMaskFilter : public SkMaskFilter {
+public:
+    SkGammaMaskFilter();
+    SkGammaMaskFilter(SkScalar gamma);
+    SkGammaMaskFilter(const uint8_t table[256]);
+    virtual ~SkGammaMaskFilter();
+
+    void setGamma(SkScalar gamma);
+    void setGammaTable(const uint8_t table[256]);
+
+    // overrides from SkMaskFilter
+    virtual SkMask::Format getFormat();
+    virtual bool filterMask(SkMask*, const SkMask&, const SkMatrix&, SkIPoint*);
+    
+    // overrides from SkFlattenable
+    virtual void flatten(SkFlattenableWriteBuffer& wb);
+    virtual Factory getFactory();
+
+protected:
+    SkGammaMaskFilter(SkFlattenableReadBuffer& rb);
+    static SkFlattenable* Factory(SkFlattenableReadBuffer&);
+
+private:
+    uint8_t fTable[256];
+    
+    typedef SkMaskFilter INHERITED;
+};
+
+#endif
+