65 lines
2.4 KiB
C++
65 lines
2.4 KiB
C++
/*
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* Copyright (C) 2008 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#ifndef SkDrawLooper_DEFINED
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#define SkDrawLooper_DEFINED
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#include "SkFlattenable.h"
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////////////////// EXPERIMENTAL //////////////////////////
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class SkCanvas;
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class SkPaint;
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/** \class SkDrawLooper
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Subclasses of SkDrawLooper can be attached to a SkPaint. Where they are,
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and something is drawn to a canvas with that paint, the looper subclass will
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be called, allowing it to modify the canvas and/or paint for that draw call.
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More than that, via the next() method, the looper can modify the draw to be
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invoked multiple times (hence the name loop-er), allow it to perform effects
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like shadows or frame/fills, that require more than one pass.
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*/
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class SkDrawLooper : public SkFlattenable {
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public:
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/** Called right before something is being drawn to the specified canvas
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with the specified paint. Subclass that want to modify either parameter
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can do so now.
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*/
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virtual void init(SkCanvas*, SkPaint*) {}
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/** Called in a loop (after init()). Each time true is returned, the object
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is drawn (possibly with a modified canvas and/or paint). When false is
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finally returned, drawing for the object stops.
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*/
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virtual bool next() { return false; }
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/** Called after the looper has finally returned false from next(), allowing
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the looper to restore the canvas/paint to their original states.
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is this required, since the subclass knows when it is done???
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should we pass the canvas/paint here, and/or to the next call
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so that subclasses don't need to retain pointers to them during the
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loop?
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*/
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virtual void restore() {}
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protected:
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SkDrawLooper() {}
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SkDrawLooper(SkFlattenableReadBuffer& buffer) : INHERITED(buffer) {}
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private:
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typedef SkFlattenable INHERITED;
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};
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#endif
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