| /* |
| * 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 |