reed@android.com | 8a1c16f | 2008-12-17 15:59:43 +0000 | [diff] [blame^] | 1 | /* |
| 2 | * Copyright (C) 2006 The Android Open Source Project |
| 3 | * |
| 4 | * Licensed under the Apache License, Version 2.0 (the "License"); |
| 5 | * you may not use this file except in compliance with the License. |
| 6 | * You may obtain a copy of the License at |
| 7 | * |
| 8 | * http://www.apache.org/licenses/LICENSE-2.0 |
| 9 | * |
| 10 | * Unless required by applicable law or agreed to in writing, software |
| 11 | * distributed under the License is distributed on an "AS IS" BASIS, |
| 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 13 | * See the License for the specific language governing permissions and |
| 14 | * limitations under the License. |
| 15 | */ |
| 16 | |
| 17 | #ifndef SkMaskFilter_DEFINED |
| 18 | #define SkMaskFilter_DEFINED |
| 19 | |
| 20 | #include "SkFlattenable.h" |
| 21 | #include "SkMask.h" |
| 22 | |
| 23 | class SkBlitter; |
| 24 | class SkBounder; |
| 25 | class SkMatrix; |
| 26 | class SkPath; |
| 27 | class SkRegion; |
| 28 | |
| 29 | /** \class SkMaskFilter |
| 30 | |
| 31 | SkMaskFilter is the base class for object that perform transformations on |
| 32 | an alpha-channel mask before drawing it. A subclass of SkMaskFilter may be |
| 33 | installed into a SkPaint. Once there, each time a primitive is drawn, it |
| 34 | is first scan converted into a SkMask::kA8_Format mask, and handed to the |
| 35 | filter, calling its filterMask() method. If this returns true, then the |
| 36 | new mask is used to render into the device. |
| 37 | |
| 38 | Blur and emboss are implemented as subclasses of SkMaskFilter. |
| 39 | */ |
| 40 | class SkMaskFilter : public SkFlattenable { |
| 41 | public: |
| 42 | SkMaskFilter() {} |
| 43 | |
| 44 | /** Returns the format of the resulting mask that this subclass will return |
| 45 | when its filterMask() method is called. |
| 46 | */ |
| 47 | virtual SkMask::Format getFormat() = 0; |
| 48 | |
| 49 | /** Create a new mask by filter the src mask. |
| 50 | If src.fImage == null, then do not allocate or create the dst image |
| 51 | but do fill out the other fields in dstMask. |
| 52 | If you do allocate a dst image, use SkMask::AllocImage() |
| 53 | If this returns false, dst mask is ignored. |
| 54 | @param dst the result of the filter. If src.fImage == null, dst should not allocate its image |
| 55 | @param src the original image to be filtered. |
| 56 | @param matrix the CTM |
| 57 | @param margin if not null, return the buffer dx/dy need when calculating the effect. Used when |
| 58 | drawing a clipped object to know how much larger to allocate the src before |
| 59 | applying the filter. If returning false, ignore this parameter. |
| 60 | @return true if the dst mask was correctly created. |
| 61 | */ |
| 62 | virtual bool filterMask(SkMask* dst, const SkMask& src, const SkMatrix&, SkIPoint* margin); |
| 63 | |
| 64 | /** Helper method that, given a path in device space, will rasterize it into a kA8_Format mask |
| 65 | and then call filterMask(). If this returns true, the specified blitter will be called |
| 66 | to render that mask. Returns false if filterMask() returned false. |
| 67 | This method is not exported to java. |
| 68 | */ |
| 69 | bool filterPath(const SkPath& devPath, const SkMatrix& devMatrix, |
| 70 | const SkRegion& devClip, SkBounder*, SkBlitter* blitter); |
| 71 | |
| 72 | virtual void flatten(SkFlattenableWriteBuffer& ) {} |
| 73 | protected: |
| 74 | // empty for now, but lets get our subclass to remember to init us for the future |
| 75 | SkMaskFilter(SkFlattenableReadBuffer&) {} |
| 76 | }; |
| 77 | |
| 78 | /** \class SkAutoMaskImage |
| 79 | |
| 80 | Stack class used to manage the fImage buffer in a SkMask. |
| 81 | When this object loses scope, the buffer is freed with SkMask::FreeImage(). |
| 82 | */ |
| 83 | class SkAutoMaskImage { |
| 84 | public: |
| 85 | SkAutoMaskImage(SkMask* mask, bool alloc) |
| 86 | { |
| 87 | if (alloc) |
| 88 | mask->fImage = SkMask::AllocImage(mask->computeImageSize()); |
| 89 | fImage = mask->fImage; |
| 90 | } |
| 91 | ~SkAutoMaskImage() |
| 92 | { |
| 93 | SkMask::FreeImage(fImage); |
| 94 | } |
| 95 | private: |
| 96 | uint8_t* fImage; |
| 97 | }; |
| 98 | |
| 99 | #endif |
| 100 | |