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* Copyright 2011 Google Inc.
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
#ifndef SkImageFilter_DEFINED
#define SkImageFilter_DEFINED
#include "include/core/SkFlattenable.h"
#include "include/core/SkRect.h"
#include "include/core/SkRefCnt.h"
#include "include/private/base/SkAPI.h"
#include <cstddef>
class SkColorFilter;
class SkMatrix;
struct SkDeserialProcs;
* Base class for image filters. If one is installed in the paint, then all drawing occurs as
* usual, but it is as if the drawing happened into an offscreen (before the xfermode is applied).
* This offscreen bitmap will then be handed to the imagefilter, who in turn creates a new bitmap
* which is what will finally be drawn to the device (using the original xfermode).
* The local space of image filters matches the local space of the drawn geometry. For instance if
* there is rotation on the canvas, the blur will be computed along those rotated axes and not in
* the device space. In order to achieve this result, the actual drawing of the geometry may happen
* in an unrotated coordinate system so that the filtered image can be computed more easily, and
* then it will be post transformed to match what would have been produced if the geometry were
* drawn with the total canvas matrix to begin with.
class SK_API SkImageFilter : public SkFlattenable {
enum MapDirection {
* Map a device-space rect recursively forward or backward through the filter DAG.
* kForward_MapDirection is used to determine which pixels of the destination canvas a source
* image rect would touch after filtering. kReverse_MapDirection is used to determine which rect
* of the source image would be required to fill the given rect (typically, clip bounds). Used
* for clipping and temp-buffer allocations, so the result need not be exact, but should never
* be smaller than the real answer. The default implementation recursively unions all input
* bounds, or returns the source rect if no inputs.
* In kReverse mode, 'inputRect' is the device-space bounds of the input pixels. In kForward
* mode it should always be null. If 'inputRect' is null in kReverse mode the resulting answer
* may be incorrect.
SkIRect filterBounds(const SkIRect& src, const SkMatrix& ctm,
MapDirection, const SkIRect* inputRect = nullptr) const;
* Returns whether this image filter is a color filter and puts the color filter into the
* "filterPtr" parameter if it can. Does nothing otherwise.
* If this returns false, then the filterPtr is unchanged.
* If this returns true, then if filterPtr is not null, it must be set to a ref'd colorfitler
* (i.e. it may not be set to NULL).
bool isColorFilterNode(SkColorFilter** filterPtr) const;
// DEPRECATED : use isColorFilterNode() instead
bool asColorFilter(SkColorFilter** filterPtr) const {
return this->isColorFilterNode(filterPtr);
* Returns true (and optionally returns a ref'd filter) if this imagefilter can be completely
* replaced by the returned colorfilter. i.e. the two effects will affect drawing in the same
* way.
bool asAColorFilter(SkColorFilter** filterPtr) const;
* Returns the number of inputs this filter will accept (some inputs can be NULL).
int countInputs() const;
* Returns the input filter at a given index, or NULL if no input is connected. The indices
* used are filter-specific.
const SkImageFilter* getInput(int i) const;
// Default impl returns union of all input bounds.
virtual SkRect computeFastBounds(const SkRect& bounds) const;
// Can this filter DAG compute the resulting bounds of an object-space rectangle?
bool canComputeFastBounds() const;
* If this filter can be represented by another filter + a localMatrix, return that filter,
* else return null.
sk_sp<SkImageFilter> makeWithLocalMatrix(const SkMatrix& matrix) const;
static sk_sp<SkImageFilter> Deserialize(const void* data, size_t size,
const SkDeserialProcs* procs = nullptr) {
return sk_sp<SkImageFilter>(static_cast<SkImageFilter*>(
SkFlattenable::Deserialize(kSkImageFilter_Type, data, size, procs).release()));
sk_sp<SkImageFilter> refMe() const {
return sk_ref_sp(const_cast<SkImageFilter*>(this));
friend class SkImageFilter_Base;
using INHERITED = SkFlattenable;