2 * Copyright 2011 Google Inc.
4 * Use of this source code is governed by a BSD-style license that can be
5 * found in the LICENSE file.
8 #ifndef SkImageFilter_DEFINED
9 #define SkImageFilter_DEFINED
11 #include "include/core/SkFlattenable.h"
12 #include "include/core/SkMatrix.h"
13 #include "include/core/SkRect.h"
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).
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.
30 class SK_API SkImageFilter : public SkFlattenable {
33 kForward_MapDirection,
34 kReverse_MapDirection,
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.
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
49 SkIRect filterBounds(const SkIRect& src, const SkMatrix& ctm,
50 MapDirection, const SkIRect* inputRect = nullptr) const;
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).
59 bool isColorFilterNode(SkColorFilter** filterPtr) const;
61 // DEPRECATED : use isColorFilterNode() instead
62 bool asColorFilter(SkColorFilter** filterPtr) const {
63 return this->isColorFilterNode(filterPtr);
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
71 bool asAColorFilter(SkColorFilter** filterPtr) const;
74 * Returns the number of inputs this filter will accept (some inputs can be NULL).
76 int countInputs() const;
79 * Returns the input filter at a given index, or NULL if no input is connected. The indices
80 * used are filter-specific.
82 const SkImageFilter* getInput(int i) const;
84 // Default impl returns union of all input bounds.
85 virtual SkRect computeFastBounds(const SkRect& bounds) const;
87 // Can this filter DAG compute the resulting bounds of an object-space rectangle?
88 bool canComputeFastBounds() const;
91 * If this filter can be represented by another filter + a localMatrix, return that filter,
94 sk_sp<SkImageFilter> makeWithLocalMatrix(const SkMatrix& matrix) const;
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()));
104 sk_sp<SkImageFilter> refMe() const {
105 return sk_ref_sp(const_cast<SkImageFilter*>(this));
109 friend class SkImageFilter_Base;
111 using INHERITED = SkFlattenable;