| /* |
| * Copyright (C) 2008 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" |
| |
| ////////////////// EXPERIMENTAL ////////////////////////// |
| |
| 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 SkDrawLooper : public SkFlattenable { |
| public: |
| /** Called right before something is being drawn to the specified canvas |
| with the specified paint. Subclass that want to modify either parameter |
| can do so now. |
| */ |
| virtual void init(SkCanvas*, SkPaint*) {} |
| /** 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. |
| */ |
| virtual bool next() { return false; } |
| /** Called after the looper has finally returned false from next(), allowing |
| the looper to restore the canvas/paint to their original states. |
| is this required, since the subclass knows when it is done??? |
| should we pass the canvas/paint here, and/or to the next call |
| so that subclasses don't need to retain pointers to them during the |
| loop? |
| */ |
| virtual void restore() {} |
| |
| protected: |
| SkDrawLooper() {} |
| SkDrawLooper(SkFlattenableReadBuffer& buffer) : INHERITED(buffer) {} |
| |
| private: |
| typedef SkFlattenable INHERITED; |
| }; |
| |
| #endif |