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* Copyright 2017 Google Inc.
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
#ifndef SkDrawShadowInfo_DEFINED
#define SkDrawShadowInfo_DEFINED
#include "SkColor.h"
#include "SkPoint.h"
#include "SkPoint3.h"
class SkMatrix;
class SkPath;
struct SkRect;
struct SkDrawShadowRec {
SkPoint3 fZPlaneParams;
SkPoint3 fLightPos;
SkScalar fLightRadius;
SkColor fAmbientColor;
SkColor fSpotColor;
uint32_t fFlags;
namespace SkDrawShadowMetrics {
static constexpr auto kAmbientHeightFactor = 1.0f / 128.0f;
static constexpr auto kAmbientGeomFactor = 64.0f;
inline SkScalar AmbientBlurRadius(SkScalar height) {
return height*kAmbientHeightFactor*kAmbientGeomFactor;
inline SkScalar AmbientRecipAlpha(SkScalar height) {
return 1.0f + SkTMax(height*kAmbientHeightFactor, 0.0f);
inline SkScalar SpotBlurRadius(SkScalar occluderZ, SkScalar lightZ, SkScalar lightRadius) {
return lightRadius*SkTPin(occluderZ / (lightZ - occluderZ), 0.0f, 0.95f);
inline void GetSpotParams(SkScalar occluderZ, SkScalar lightX, SkScalar lightY, SkScalar lightZ,
SkScalar lightRadius,
SkScalar* blurRadius, SkScalar* scale, SkVector* translate) {
SkScalar zRatio = SkTPin(occluderZ / (lightZ - occluderZ), 0.0f, 0.95f);
*blurRadius = lightRadius*zRatio;
*scale = SkTMax(lightZ / (lightZ - occluderZ), 1.0f);
*translate = SkVector::Make(-zRatio * lightX, -zRatio * lightY);
// get bounds prior to the ctm being applied
void GetLocalBounds(const SkPath&, const SkDrawShadowRec&, const SkMatrix& ctm, SkRect* bounds);