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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 SkShadowUtils_DEFINED
#define SkShadowUtils_DEFINED
#include "SkColor.h"
#include "SkScalar.h"
#include "../private/SkShadowFlags.h"
#include <functional>
class SkCanvas;
class SkPath;
class SkResourceCache;
class SkShadowUtils {
public:
/**
* Draw an offset spot shadow and outlining ambient shadow for the given path using a disc
* light.
*
* @param canvas The canvas on which to draw the shadows.
* @param path The occluder used to generate the shadows.
* @param occluderHeight The vertical offset of the occluder from the canvas. This is
* independent of the canvas's current matrix.
* @param lightPos The 3D position of the light relative to the canvas plane. This is
* independent of the canvas's current matrix.
* @param lightRadius The radius of the disc light.
* @param ambientAlpha The maximum alpha of the ambient shadow.
* @param spotAlpha The maxium alpha of the spot shadow.
* @param color The shadow color.
* @param flags Options controlling opaque occluder optimizations and shadow appearance. See
* SkShadowFlags.
* @param cache Used for testing purposes. Clients should pass nullptr (default).
*/
static void DrawShadow(SkCanvas* canvas, const SkPath& path, SkScalar occluderHeight,
const SkPoint3& lightPos, SkScalar lightRadius, SkScalar ambientAlpha,
SkScalar spotAlpha, SkColor color,
uint32_t flags = SkShadowFlags::kNone_ShadowFlag,
SkResourceCache* cache = nullptr);
/**
* Draw an offset spot shadow and outlining ambient shadow for the given path using a disc
* light. Takes a function to vary the z value based on the transformed x and y position.
* This shadow will not be cached, as the assumption is that this will be used for animation.
*
* @param canvas The canvas on which to draw the shadows.
* @param path The occluder used to generate the shadows.
* @param heightFunc A function which returns the vertical offset of the occluder from the
* canvas based on local x and y values (the current matrix is not applied).
* @param lightPos The 3D position of the light relative to the canvas plane. This is
* independent of the canvas's current matrix.
* @param lightRadius The radius of the disc light.
* @param ambientAlpha The maximum alpha of the ambient shadow.
* @param spotAlpha The maxium alpha of the spot shadow.
* @param color The shadow color.
* @param flags Options controlling opaque occluder optimizations and shadow appearance. See
* SkShadowFlags.
*/
static void DrawUncachedShadow(SkCanvas* canvas, const SkPath& path,
std::function<SkScalar(SkScalar, SkScalar)> heightFunc,
const SkPoint3& lightPos, SkScalar lightRadius,
SkScalar ambientAlpha, SkScalar spotAlpha, SkColor color,
uint32_t flags = SkShadowFlags::kNone_ShadowFlag);
};
#endif
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