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* Copyright 2006 The Android Open Source Project
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
#ifndef SkTableMaskFilter_DEFINED
#define SkTableMaskFilter_DEFINED
#include "SkMaskFilter.h"
#include "SkScalar.h"
/** \class SkTableMaskFilter
Applies a table lookup on each of the alpha values in the mask.
Helper methods create some common tables (e.g. gamma, clipping)
class SK_API SkTableMaskFilter : public SkMaskFilter {
/** 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 SkMaskFilter* Create(const uint8_t table[256]) {
return new SkTableMaskFilter(table);
static SkMaskFilter* CreateGamma(SkScalar gamma) {
uint8_t table[256];
MakeGammaTable(table, gamma);
return new SkTableMaskFilter(table);
static SkMaskFilter* CreateClip(uint8_t min, uint8_t max) {
uint8_t table[256];
MakeClipTable(table, min, max);
return new SkTableMaskFilter(table);
SkMask::Format getFormat() const override;
bool filterMask(SkMask*, const SkMask&, const SkMatrix&, SkIPoint*) const override;
~SkTableMaskFilter() override;
void flatten(SkWriteBuffer&) const override;
explicit SkTableMaskFilter(const uint8_t table[256]);
uint8_t fTable[256];
typedef SkMaskFilter INHERITED;