1 files changed, 31 insertions, 13 deletions
diff --git a/include/effects/SkGammaMaskFilter.h b/include/effects/SkTableMaskFilter.h
index fdff43d1e8..a57053d6f3 100644
--- a/include/effects/SkGammaMaskFilter.h
+++ b/include/effects/SkTableMaskFilter.h
@@ -14,27 +14,45 @@
  * limitations under the License.
  */
 
-#ifndef SkGammaMaskFilter_DEFINED
-#define SkGammaMaskFilter_DEFINED
+#ifndef SkTableMaskFilter_DEFINED
+#define SkTableMaskFilter_DEFINED
 
 #include "SkMaskFilter.h"
 #include "SkScalar.h"
 
-/** \class SkGammaMaskFilter
+/** \class SkTableMaskFilter
  
     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.
+    Helper methods create some common tables (e.g. gamma, clipping)
  */
-class SkGammaMaskFilter : public SkMaskFilter {
+class SkTableMaskFilter : public SkMaskFilter {
 public:
-    SkGammaMaskFilter();
-    SkGammaMaskFilter(SkScalar gamma);
-    SkGammaMaskFilter(const uint8_t table[256]);
-    virtual ~SkGammaMaskFilter();
+    SkTableMaskFilter();
+    SkTableMaskFilter(const uint8_t table[256]);
+    virtual ~SkTableMaskFilter();
 
-    void setGamma(SkScalar gamma);
-    void setGammaTable(const uint8_t table[256]);
+    void setTable(const uint8_t table[256]);
+
+    /** Utility that sets the gamma table
+     */
+    static void MakeGammaTable(uint8_t table[256], SkScalar gamma);
+
+    /** Utility that creates a clipping table: clamps values below min to 0
+        and above max to 255, and rescales the remaining into 0..255
+     */
+    static void MakeClipTable(uint8_t table[256], uint8_t min, uint8_t max);
+
+    static SkTableMaskFilter* CreateGamma(SkScalar gamma) {
+        uint8_t table[256];
+        MakeGammaTable(table, gamma);
+        return SkNEW_ARGS(SkTableMaskFilter, (table));
+    }
+
+    static SkTableMaskFilter* CreateClip(uint8_t min, uint8_t max) {
+        uint8_t table[256];
+        MakeClipTable(table, min, max);
+        return SkNEW_ARGS(SkTableMaskFilter, (table));
+    }
 
     // overrides from SkMaskFilter
     virtual SkMask::Format getFormat();
@@ -45,7 +63,7 @@ public:
     virtual Factory getFactory();
 
 protected:
-    SkGammaMaskFilter(SkFlattenableReadBuffer& rb);
+    SkTableMaskFilter(SkFlattenableReadBuffer& rb);
     static SkFlattenable* Factory(SkFlattenableReadBuffer&);
 
 private: