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* Copyright 2006 The Android Open Source Project
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
#ifndef SkBlurMaskFilter_DEFINED
#define SkBlurMaskFilter_DEFINED
// we include this since our callers will need to at least be able to ref/unref
#include "SkMaskFilter.h"
#include "SkScalar.h"
#include "SkBlurTypes.h"
class SK_API SkBlurMaskFilter {
* If radius > 0, return the corresponding sigma, else return 0. Use this to convert from the
* (legacy) idea of specify the blur "radius" to the standard notion of specifying its sigma.
static SkScalar ConvertRadiusToSigma(SkScalar radius);
enum BlurFlags {
kNone_BlurFlag = 0x00,
/** The blur layer's radius is not affected by transforms */
kIgnoreTransform_BlurFlag = 0x01,
/** Use a smother, higher qulity blur algorithm */
kHighQuality_BlurFlag = 0x02,
/** mask for all blur flags */
kAll_BlurFlag = 0x03
/** Create a blur maskfilter.
* @param style The SkBlurStyle to use
* @param sigma Standard deviation of the Gaussian blur to apply. Must be > 0.
* @param occluder The rect for which no pixels need be drawn (b.c. it will be overdrawn
* with some opaque object. This is just a hint which backends are free to
* ignore.
* @param flags Flags to use - defaults to none
* @return The new blur maskfilter
static sk_sp<SkMaskFilter> Make(SkBlurStyle style, SkScalar sigma,
const SkRect& occluder, uint32_t flags = kNone_BlurFlag);
static sk_sp<SkMaskFilter> Make(SkBlurStyle style, SkScalar sigma,
uint32_t flags = kNone_BlurFlag) {
return Make(style, sigma, SkRect::MakeEmpty(), flags);
/** Create an emboss maskfilter
@param blurSigma standard deviation of the Gaussian blur to apply
before applying lighting (e.g. 3)
@param direction array of 3 scalars [x, y, z] specifying the direction of the light source
@param ambient 0...1 amount of ambient light
@param specular coefficient for specular highlights (e.g. 8)
@return the emboss maskfilter
static sk_sp<SkMaskFilter> MakeEmboss(SkScalar blurSigma, const SkScalar direction[3],
SkScalar ambient, SkScalar specular);
static const int kMaxDivisions = 6;
// This method computes all the parameters for drawing a partially occluded nine-patched
// blurred rrect mask:
// rrectToDraw - the integerized rrect to draw in the mask
// widthHeight - how large to make the mask (rrectToDraw will be centered in this coord sys)
// rectXs, rectYs - the x & y coordinates of the covering geometry lattice
// texXs, texYs - the texture coordinate at each point in rectXs & rectYs
// numXs, numYs - number of coordinates in the x & y directions
// skipMask - bit mask that contains a 1-bit whenever one of the cells is occluded
// It returns true if 'devRRect' is nine-patchable
static bool ComputeBlurredRRectParams(const SkRRect& srcRRect, const SkRRect& devRRect,
const SkRect& occluder,
SkScalar sigma, SkScalar xformedSigma,
SkRRect* rrectToDraw,
SkISize* widthHeight,
SkScalar rectXs[kMaxDivisions],
SkScalar rectYs[kMaxDivisions],
SkScalar texXs[kMaxDivisions],
SkScalar texYs[kMaxDivisions],
int* numXs, int* numYs, uint32_t* skipMask);
SkBlurMaskFilter(); // can't be instantiated