skia2/include/utils/SkShadowUtils.h
Jim Van Verth b436655ad5 Add height function to shadow tessellators.
Prep work for adding perspective support.

Bug: skia:
Change-Id: Id07d3050afb3f0d001b885e482adb8d03125b619
Reviewed-on: https://skia-review.googlesource.com/10167
Commit-Queue: Jim Van Verth <jvanverth@google.com>
Reviewed-by: Brian Salomon <bsalomon@google.com>
2017-03-27 19:06:59 +00:00

72 lines
3.2 KiB
C++

/*
* 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