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/*
* Copyright (C) 2011 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 SkDrawLooper_DEFINED
#define SkDrawLooper_DEFINED
#include "SkFlattenable.h"
class SkCanvas;
class SkPaint;
/** \class SkDrawLooper
Subclasses of SkDrawLooper can be attached to a SkPaint. Where they are,
and something is drawn to a canvas with that paint, the looper subclass will
be called, allowing it to modify the canvas and/or paint for that draw call.
More than that, via the next() method, the looper can modify the draw to be
invoked multiple times (hence the name loop-er), allow it to perform effects
like shadows or frame/fills, that require more than one pass.
*/
class SK_API SkDrawLooper : public SkFlattenable {
public:
/**
* Called right before something is being drawn. This will be followed by
* calls to next() until next() returns false.
*/
virtual void init(SkCanvas*) = 0;
/**
* Called in a loop (after init()). Each time true is returned, the object
* is drawn (possibly with a modified canvas and/or paint). When false is
* finally returned, drawing for the object stops.
*
* On each call, the paint will be in its original state, but the canvas
* will be as it was following the previous call to next() or init().
*
* The implementation must ensure that, when next() finally returns false,
* that the canvas has been restored to the state it was initially, before
* init() was first called.
*/
virtual bool next(SkCanvas*, SkPaint* paint) = 0;
protected:
SkDrawLooper() {}
SkDrawLooper(SkFlattenableReadBuffer& buffer) : INHERITED(buffer) {}
private:
typedef SkFlattenable INHERITED;
};
#endif
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