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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 "SkPoint3.h"
#include "SkScalar.h"
#include "../private/SkShadowFlags.h"
class SkCanvas;
class SkPath;
class SkResourceCache;
class SK_API 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 ambientColor The color of the ambient shadow.
* @param spotColor The color of the spot shadow.
* @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,
SkColor ambientColor, SkColor spotColor,
uint32_t flags = SkShadowFlags::kNone_ShadowFlag);
/**
* Deprecated version that uses one color and two alphas, and supports tonal color.
*
* 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& zPlane,
const SkPoint3& lightPos, SkScalar lightRadius, SkScalar ambientAlpha,
SkScalar spotAlpha, SkColor color,
uint32_t flags = SkShadowFlags::kNone_ShadowFlag) {
SkColor ambientColor;
SkColor spotColor;
if (flags & SkShadowFlags::kDisableTonalColor_ShadowFlag) {
ambientColor = SkColorSetARGB(ambientAlpha*SkColorGetA(color), SkColorGetR(color),
SkColorGetG(color), SkColorGetB(color));
spotColor = SkColorSetARGB(spotAlpha*SkColorGetA(color), SkColorGetR(color),
SkColorGetG(color), SkColorGetB(color));
} else {
SkColor inAmbient = SkColorSetA(color, ambientAlpha*SkColorGetA(color));
SkColor inSpot = SkColorSetA(color, spotAlpha*SkColorGetA(color));
ComputeTonalColors(inAmbient, inSpot, &ambientColor, &spotColor);
}
DrawShadow(canvas, path, zPlane, lightPos, lightRadius, ambientColor, spotColor, flags);
}
/**
* Deprecated version with height value (to be removed when Flutter is updated).
*
* 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.
*/
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);
}
/**
* Helper routine to compute color values for one-pass tonal alpha.
*
* @param inAmbientColor Original ambient color
* @param inSpotColor Original spot color
* @param outAmbientColor Modified ambient color
* @param outSpotColor Modified spot color
*/
static void ComputeTonalColors(SkColor inAmbientColor, SkColor inSpotColor,
SkColor* outAmbientColor, SkColor* outSpotColor);
};
#endif
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