| |
| /* |
| * 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 "include/core/SkColor.h" |
| #include "include/core/SkScalar.h" |
| #include "include/core/SkTypes.h" |
| #include "include/private/SkShadowFlags.h" |
| |
| #include <cstdint> |
| |
| class SkCanvas; |
| class SkMatrix; |
| class SkPath; |
| struct SkPoint3; |
| struct SkRect; |
| |
| 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 Generally, the 3D position of the light relative to the canvas plane. |
| * If kDirectionalLight_ShadowFlag is set, this specifies a vector pointing |
| * towards the light. |
| * @param lightRadius Generally, the radius of the disc light. |
| * If DirectionalLight_ShadowFlag is set, this specifies the amount of |
| * blur when the occluder is at Z offset == 1. The blur will grow linearly |
| * as the Z value increases. |
| * @param ambientColor The color of the ambient shadow. |
| * @param spotColor The color of the spot shadow. |
| * @param flags Options controlling opaque occluder optimizations, shadow appearance, |
| * and light position. 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); |
| |
| /** |
| * Generate bounding box for shadows relative to path. Includes both the ambient and spot |
| * shadow bounds. |
| * |
| * @param ctm Current transformation matrix to device space. |
| * @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 Generally, the 3D position of the light relative to the canvas plane. |
| * If kDirectionalLight_ShadowFlag is set, this specifies a vector pointing |
| * towards the light. |
| * @param lightRadius Generally, the radius of the disc light. |
| * If DirectionalLight_ShadowFlag is set, this specifies the amount of |
| * blur when the occluder is at Z offset == 1. The blur will grow linearly |
| * as the Z value increases. |
| * @param flags Options controlling opaque occluder optimizations, shadow appearance, |
| * and light position. See SkShadowFlags. |
| * @param bounds Return value for shadow bounding box. |
| * @return Returns true if successful, false otherwise. |
| */ |
| static bool GetLocalBounds(const SkMatrix& ctm, const SkPath& path, |
| const SkPoint3& zPlaneParams, const SkPoint3& lightPos, |
| SkScalar lightRadius, uint32_t flags, SkRect* bounds); |
| |
| /** |
| * 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 |