1 /* 2 * Copyright 2011 Google Inc. 3 * 4 * Use of this source code is governed by a BSD-style license that can be 5 * found in the LICENSE file. 6 */ 7 8 #ifndef SkImageFilter_DEFINED 9 #define SkImageFilter_DEFINED 10 11 #include "include/core/SkFlattenable.h" 12 #include "include/core/SkMatrix.h" 13 #include "include/core/SkRect.h" 14 15 class SkColorFilter; 16 17 /** 18 * Base class for image filters. If one is installed in the paint, then all drawing occurs as 19 * usual, but it is as if the drawing happened into an offscreen (before the xfermode is applied). 20 * This offscreen bitmap will then be handed to the imagefilter, who in turn creates a new bitmap 21 * which is what will finally be drawn to the device (using the original xfermode). 22 * 23 * The local space of image filters matches the local space of the drawn geometry. For instance if 24 * there is rotation on the canvas, the blur will be computed along those rotated axes and not in 25 * the device space. In order to achieve this result, the actual drawing of the geometry may happen 26 * in an unrotated coordinate system so that the filtered image can be computed more easily, and 27 * then it will be post transformed to match what would have been produced if the geometry were 28 * drawn with the total canvas matrix to begin with. 29 */ 30 class SK_API SkImageFilter : public SkFlattenable { 31 public: 32 enum MapDirection { 33 kForward_MapDirection, 34 kReverse_MapDirection, 35 }; 36 /** 37 * Map a device-space rect recursively forward or backward through the filter DAG. 38 * kForward_MapDirection is used to determine which pixels of the destination canvas a source 39 * image rect would touch after filtering. kReverse_MapDirection is used to determine which rect 40 * of the source image would be required to fill the given rect (typically, clip bounds). Used 41 * for clipping and temp-buffer allocations, so the result need not be exact, but should never 42 * be smaller than the real answer. The default implementation recursively unions all input 43 * bounds, or returns the source rect if no inputs. 44 * 45 * In kReverse mode, 'inputRect' is the device-space bounds of the input pixels. In kForward 46 * mode it should always be null. If 'inputRect' is null in kReverse mode the resulting answer 47 * may be incorrect. 48 */ 49 SkIRect filterBounds(const SkIRect& src, const SkMatrix& ctm, 50 MapDirection, const SkIRect* inputRect = nullptr) const; 51 52 /** 53 * Returns whether this image filter is a color filter and puts the color filter into the 54 * "filterPtr" parameter if it can. Does nothing otherwise. 55 * If this returns false, then the filterPtr is unchanged. 56 * If this returns true, then if filterPtr is not null, it must be set to a ref'd colorfitler 57 * (i.e. it may not be set to NULL). 58 */ 59 bool isColorFilterNode(SkColorFilter** filterPtr) const; 60 61 // DEPRECATED : use isColorFilterNode() instead asColorFilter(SkColorFilter ** filterPtr)62 bool asColorFilter(SkColorFilter** filterPtr) const { 63 return this->isColorFilterNode(filterPtr); 64 } 65 66 /** 67 * Returns true (and optionally returns a ref'd filter) if this imagefilter can be completely 68 * replaced by the returned colorfilter. i.e. the two effects will affect drawing in the same 69 * way. 70 */ 71 bool asAColorFilter(SkColorFilter** filterPtr) const; 72 73 /** 74 * Returns the number of inputs this filter will accept (some inputs can be NULL). 75 */ 76 int countInputs() const; 77 78 /** 79 * Returns the input filter at a given index, or NULL if no input is connected. The indices 80 * used are filter-specific. 81 */ 82 const SkImageFilter* getInput(int i) const; 83 84 // Default impl returns union of all input bounds. 85 virtual SkRect computeFastBounds(const SkRect& bounds) const; 86 87 // Can this filter DAG compute the resulting bounds of an object-space rectangle? 88 bool canComputeFastBounds() const; 89 90 /** 91 * If this filter can be represented by another filter + a localMatrix, return that filter, 92 * else return null. 93 */ 94 sk_sp<SkImageFilter> makeWithLocalMatrix(const SkMatrix& matrix) const; 95 96 static sk_sp<SkImageFilter> Deserialize(const void* data, size_t size, 97 const SkDeserialProcs* procs = nullptr) { 98 return sk_sp<SkImageFilter>(static_cast<SkImageFilter*>( 99 SkFlattenable::Deserialize(kSkImageFilter_Type, data, size, procs).release())); 100 } 101 102 protected: 103 refMe()104 sk_sp<SkImageFilter> refMe() const { 105 return sk_ref_sp(const_cast<SkImageFilter*>(this)); 106 } 107 108 private: 109 friend class SkImageFilter_Base; 110 111 using INHERITED = SkFlattenable; 112 }; 113 114 #endif 115