1 2 /* 3 * Copyright 2017 Google Inc. 4 * 5 * Use of this source code is governed by a BSD-style license that can be 6 * found in the LICENSE file. 7 */ 8 #ifndef SkShadowUtils_DEFINED 9 #define SkShadowUtils_DEFINED 10 11 #include "SkColor.h" 12 #include "SkScalar.h" 13 #include "../private/SkShadowFlags.h" 14 #include <functional> 15 16 class SkCanvas; 17 class SkPath; 18 class SkResourceCache; 19 20 class SkShadowUtils { 21 public: 22 /** 23 * Draw an offset spot shadow and outlining ambient shadow for the given path using a disc 24 * light. 25 * 26 * @param canvas The canvas on which to draw the shadows. 27 * @param path The occluder used to generate the shadows. 28 * @param occluderHeight The vertical offset of the occluder from the canvas. This is 29 * independent of the canvas's current matrix. 30 * @param lightPos The 3D position of the light relative to the canvas plane. This is 31 * independent of the canvas's current matrix. 32 * @param lightRadius The radius of the disc light. 33 * @param ambientAlpha The maximum alpha of the ambient shadow. 34 * @param spotAlpha The maxium alpha of the spot shadow. 35 * @param color The shadow color. 36 * @param flags Options controlling opaque occluder optimizations and shadow appearance. See 37 * SkShadowFlags. 38 * @param cache Used for testing purposes. Clients should pass nullptr (default). 39 */ 40 static void DrawShadow(SkCanvas* canvas, const SkPath& path, SkScalar occluderHeight, 41 const SkPoint3& lightPos, SkScalar lightRadius, SkScalar ambientAlpha, 42 SkScalar spotAlpha, SkColor color, 43 uint32_t flags = SkShadowFlags::kNone_ShadowFlag, 44 SkResourceCache* cache = nullptr); 45 46 /** 47 * Draw an offset spot shadow and outlining ambient shadow for the given path using a disc 48 * light. Takes a function to vary the z value based on the transformed x and y position. 49 * This shadow will not be cached, as the assumption is that this will be used for animation. 50 * 51 * @param canvas The canvas on which to draw the shadows. 52 * @param path The occluder used to generate the shadows. 53 * @param heightFunc A function which returns the vertical offset of the occluder from the 54 * canvas based on local x and y values (the current matrix is not applied). 55 * @param lightPos The 3D position of the light relative to the canvas plane. This is 56 * independent of the canvas's current matrix. 57 * @param lightRadius The radius of the disc light. 58 * @param ambientAlpha The maximum alpha of the ambient shadow. 59 * @param spotAlpha The maxium alpha of the spot shadow. 60 * @param color The shadow color. 61 * @param flags Options controlling opaque occluder optimizations and shadow appearance. See 62 * SkShadowFlags. 63 */ 64 static void DrawUncachedShadow(SkCanvas* canvas, const SkPath& path, 65 std::function<SkScalar(SkScalar, SkScalar)> heightFunc, 66 const SkPoint3& lightPos, SkScalar lightRadius, 67 SkScalar ambientAlpha, SkScalar spotAlpha, SkColor color, 68 uint32_t flags = SkShadowFlags::kNone_ShadowFlag); 69 }; 70 71 #endif 72
