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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. The shadow may be cached, depending on the path type and canvas matrix. If the
* matrix is perspective or the path is volatile, it will not be cached.
*
* @param canvas The canvas on which to draw the shadows.
* @param path The occluder used to generate the shadows.
* @param zPlaneParams Values for the plane function which returns the Z 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 DrawShadow(SkCanvas* canvas, const SkPath& path, const SkPoint3& zPlaneParams,
const SkPoint3& lightPos, SkScalar lightRadius, SkScalar ambientAlpha,
SkScalar spotAlpha, SkColor color,
uint32_t flags = SkShadowFlags::kNone_ShadowFlag);
/**
* Draw an offset spot shadow and outlining ambient shadow for the given path using a disc
* light.
*
* Deprecated version with height value (to be removed when Android and Flutter are updated).
*
* @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.
*/
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) {
SkPoint3 zPlane = SkPoint3::Make(0, 0, occluderHeight);
DrawShadow(canvas, path, zPlane, lightPos, lightRadius, ambientAlpha, spotAlpha,
color, flags);
}
#ifdef SK_BUILD_FOR_ANDROID_FRAMEWORK
/**
* 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 local x and y position.
* This shadow will not be cached, as the assumption is that this will be used for animation.
*
* Deprecated (to be removed when Android is updated).
*
* @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) {
SkPoint3 zPlane;
zPlane.fZ = heightFunc(0, 0);
zPlane.fX = heightFunc(1, 0) - zPlane.fZ;
zPlane.fY = heightFunc(0, 1) - zPlane.fZ;
DrawShadow(canvas, path, zPlane, lightPos, lightRadius, ambientAlpha, spotAlpha,
color, flags);
}
#endif
};
#endif
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