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Diffstat (limited to 'src/deps/skia/include/effects/SkGradientShader.h')
| -rw-r--r-- | src/deps/skia/include/effects/SkGradientShader.h | 264 |
1 files changed, 264 insertions, 0 deletions
diff --git a/src/deps/skia/include/effects/SkGradientShader.h b/src/deps/skia/include/effects/SkGradientShader.h new file mode 100644 index 000000000..f8745c3b7 --- /dev/null +++ b/src/deps/skia/include/effects/SkGradientShader.h @@ -0,0 +1,264 @@ +/* + * Copyright 2006 The Android Open Source Project + * + * Use of this source code is governed by a BSD-style license that can be + * found in the LICENSE file. + */ + +#ifndef SkGradientShader_DEFINED +#define SkGradientShader_DEFINED + +#include "include/core/SkShader.h" + +/** \class SkGradientShader + + SkGradientShader hosts factories for creating subclasses of SkShader that + render linear and radial gradients. In general, degenerate cases should not + produce surprising results, but there are several types of degeneracies: + + * A linear gradient made from the same two points. + * A radial gradient with a radius of zero. + * A sweep gradient where the start and end angle are the same. + * A two point conical gradient where the two centers and the two radii are + the same. + + For any degenerate gradient with a decal tile mode, it will draw empty since the interpolating + region is zero area and the outer region is discarded by the decal mode. + + For any degenerate gradient with a repeat or mirror tile mode, it will draw a solid color that + is the average gradient color, since infinitely many repetitions of the gradients will fill the + shape. + + For a clamped gradient, every type is well-defined at the limit except for linear gradients. The + radial gradient with zero radius becomes the last color. The sweep gradient draws the sector + from 0 to the provided angle with the first color, with a hardstop switching to the last color. + When the provided angle is 0, this is just the solid last color again. Similarly, the two point + conical gradient becomes a circle filled with the first color, sized to the provided radius, + with a hardstop switching to the last color. When the two radii are both zero, this is just the + solid last color. + + As a linear gradient approaches the degenerate case, its shader will approach the appearance of + two half planes, each filled by the first and last colors of the gradient. The planes will be + oriented perpendicular to the vector between the two defining points of the gradient. However, + once they become the same point, Skia cannot reconstruct what that expected orientation is. To + provide a stable and predictable color in this case, Skia just uses the last color as a solid + fill to be similar to many of the other degenerate gradients' behaviors in clamp mode. +*/ +class SK_API SkGradientShader { +public: + enum Flags { + /** By default gradients will interpolate their colors in unpremul space + * and then premultiply each of the results. By setting this flag, the + * gradients will premultiply their colors first, and then interpolate + * between them. + * example: https://fiddle.skia.org/c/@GradientShader_MakeLinear + */ + kInterpolateColorsInPremul_Flag = 1 << 0, + }; + + /** Returns a shader that generates a linear gradient between the two specified points. + <p /> + @param pts The start and end points for the gradient. + @param colors The array[count] of colors, to be distributed between the two points + @param pos May be NULL. array[count] of SkScalars, or NULL, of the relative position of + each corresponding color in the colors array. If this is NULL, + the the colors are distributed evenly between the start and end point. + If this is not null, the values must begin with 0, end with 1.0, and + intermediate values must be strictly increasing. + @param count Must be >=2. The number of colors (and pos if not NULL) entries. + @param mode The tiling mode + + example: https://fiddle.skia.org/c/@GradientShader_MakeLinear + */ + static sk_sp<SkShader> MakeLinear(const SkPoint pts[2], + const SkColor colors[], const SkScalar pos[], int count, + SkTileMode mode, + uint32_t flags, const SkMatrix* localMatrix); + static sk_sp<SkShader> MakeLinear(const SkPoint pts[2], + const SkColor colors[], const SkScalar pos[], int count, + SkTileMode mode) { + return MakeLinear(pts, colors, pos, count, mode, 0, nullptr); + } + + /** Returns a shader that generates a linear gradient between the two specified points. + <p /> + @param pts The start and end points for the gradient. + @param colors The array[count] of colors, to be distributed between the two points + @param pos May be NULL. array[count] of SkScalars, or NULL, of the relative position of + each corresponding color in the colors array. If this is NULL, + the the colors are distributed evenly between the start and end point. + If this is not null, the values must begin with 0, end with 1.0, and + intermediate values must be strictly increasing. + @param count Must be >=2. The number of colors (and pos if not NULL) entries. + @param mode The tiling mode + + example: https://fiddle.skia.org/c/@GradientShader_MakeLinear + */ + static sk_sp<SkShader> MakeLinear(const SkPoint pts[2], + const SkColor4f colors[], sk_sp<SkColorSpace> colorSpace, + const SkScalar pos[], int count, SkTileMode mode, + uint32_t flags, const SkMatrix* localMatrix); + static sk_sp<SkShader> MakeLinear(const SkPoint pts[2], + const SkColor4f colors[], sk_sp<SkColorSpace> colorSpace, + const SkScalar pos[], int count, SkTileMode mode) { + return MakeLinear(pts, colors, std::move(colorSpace), pos, count, mode, 0, nullptr); + } + + /** Returns a shader that generates a radial gradient given the center and radius. + <p /> + @param center The center of the circle for this gradient + @param radius Must be positive. The radius of the circle for this gradient + @param colors The array[count] of colors, to be distributed between the center and edge of the circle + @param pos May be NULL. The array[count] of SkScalars, or NULL, of the relative position of + each corresponding color in the colors array. If this is NULL, + the the colors are distributed evenly between the center and edge of the circle. + If this is not null, the values must begin with 0, end with 1.0, and + intermediate values must be strictly increasing. + @param count Must be >= 2. The number of colors (and pos if not NULL) entries + @param mode The tiling mode + */ + static sk_sp<SkShader> MakeRadial(const SkPoint& center, SkScalar radius, + const SkColor colors[], const SkScalar pos[], int count, + SkTileMode mode, + uint32_t flags, const SkMatrix* localMatrix); + static sk_sp<SkShader> MakeRadial(const SkPoint& center, SkScalar radius, + const SkColor colors[], const SkScalar pos[], int count, + SkTileMode mode) { + return MakeRadial(center, radius, colors, pos, count, mode, 0, nullptr); + } + + /** Returns a shader that generates a radial gradient given the center and radius. + <p /> + @param center The center of the circle for this gradient + @param radius Must be positive. The radius of the circle for this gradient + @param colors The array[count] of colors, to be distributed between the center and edge of the circle + @param pos May be NULL. The array[count] of SkScalars, or NULL, of the relative position of + each corresponding color in the colors array. If this is NULL, + the the colors are distributed evenly between the center and edge of the circle. + If this is not null, the values must begin with 0, end with 1.0, and + intermediate values must be strictly increasing. + @param count Must be >= 2. The number of colors (and pos if not NULL) entries + @param mode The tiling mode + */ + static sk_sp<SkShader> MakeRadial(const SkPoint& center, SkScalar radius, + const SkColor4f colors[], sk_sp<SkColorSpace> colorSpace, + const SkScalar pos[], int count, SkTileMode mode, + uint32_t flags, const SkMatrix* localMatrix); + static sk_sp<SkShader> MakeRadial(const SkPoint& center, SkScalar radius, + const SkColor4f colors[], sk_sp<SkColorSpace> colorSpace, + const SkScalar pos[], int count, SkTileMode mode) { + return MakeRadial(center, radius, colors, std::move(colorSpace), pos, count, mode, + 0, nullptr); + } + + /** + * Returns a shader that generates a conical gradient given two circles, or + * returns NULL if the inputs are invalid. The gradient interprets the + * two circles according to the following HTML spec. + * http://dev.w3.org/html5/2dcontext/#dom-context-2d-createradialgradient + */ + static sk_sp<SkShader> MakeTwoPointConical(const SkPoint& start, SkScalar startRadius, + const SkPoint& end, SkScalar endRadius, + const SkColor colors[], const SkScalar pos[], + int count, SkTileMode mode, + uint32_t flags, const SkMatrix* localMatrix); + static sk_sp<SkShader> MakeTwoPointConical(const SkPoint& start, SkScalar startRadius, + const SkPoint& end, SkScalar endRadius, + const SkColor colors[], const SkScalar pos[], + int count, SkTileMode mode) { + return MakeTwoPointConical(start, startRadius, end, endRadius, colors, pos, count, mode, + 0, nullptr); + } + + /** + * Returns a shader that generates a conical gradient given two circles, or + * returns NULL if the inputs are invalid. The gradient interprets the + * two circles according to the following HTML spec. + * http://dev.w3.org/html5/2dcontext/#dom-context-2d-createradialgradient + */ + static sk_sp<SkShader> MakeTwoPointConical(const SkPoint& start, SkScalar startRadius, + const SkPoint& end, SkScalar endRadius, + const SkColor4f colors[], + sk_sp<SkColorSpace> colorSpace, const SkScalar pos[], + int count, SkTileMode mode, + uint32_t flags, const SkMatrix* localMatrix); + static sk_sp<SkShader> MakeTwoPointConical(const SkPoint& start, SkScalar startRadius, + const SkPoint& end, SkScalar endRadius, + const SkColor4f colors[], + sk_sp<SkColorSpace> colorSpace, const SkScalar pos[], + int count, SkTileMode mode) { + return MakeTwoPointConical(start, startRadius, end, endRadius, colors, + std::move(colorSpace), pos, count, mode, 0, nullptr); + } + + /** Returns a shader that generates a sweep gradient given a center. + <p /> + @param cx The X coordinate of the center of the sweep + @param cx The Y coordinate of the center of the sweep + @param colors The array[count] of colors, to be distributed around the center, within + the gradient angle range. + @param pos May be NULL. The array[count] of SkScalars, or NULL, of the relative + position of each corresponding color in the colors array. If this is + NULL, then the colors are distributed evenly within the angular range. + If this is not null, the values must begin with 0, end with 1.0, and + intermediate values must be strictly increasing. + @param count Must be >= 2. The number of colors (and pos if not NULL) entries + @param mode Tiling mode: controls drawing outside of the gradient angular range. + @param startAngle Start of the angular range, corresponding to pos == 0. + @param endAngle End of the angular range, corresponding to pos == 1. + */ + static sk_sp<SkShader> MakeSweep(SkScalar cx, SkScalar cy, + const SkColor colors[], const SkScalar pos[], int count, + SkTileMode mode, + SkScalar startAngle, SkScalar endAngle, + uint32_t flags, const SkMatrix* localMatrix); + static sk_sp<SkShader> MakeSweep(SkScalar cx, SkScalar cy, + const SkColor colors[], const SkScalar pos[], int count, + uint32_t flags, const SkMatrix* localMatrix) { + return MakeSweep(cx, cy, colors, pos, count, SkTileMode::kClamp, 0, 360, flags, + localMatrix); + } + static sk_sp<SkShader> MakeSweep(SkScalar cx, SkScalar cy, + const SkColor colors[], const SkScalar pos[], int count) { + return MakeSweep(cx, cy, colors, pos, count, 0, nullptr); + } + + /** Returns a shader that generates a sweep gradient given a center. + <p /> + @param cx The X coordinate of the center of the sweep + @param cx The Y coordinate of the center of the sweep + @param colors The array[count] of colors, to be distributed around the center, within + the gradient angle range. + @param pos May be NULL. The array[count] of SkScalars, or NULL, of the relative + position of each corresponding color in the colors array. If this is + NULL, then the colors are distributed evenly within the angular range. + If this is not null, the values must begin with 0, end with 1.0, and + intermediate values must be strictly increasing. + @param count Must be >= 2. The number of colors (and pos if not NULL) entries + @param mode Tiling mode: controls drawing outside of the gradient angular range. + @param startAngle Start of the angular range, corresponding to pos == 0. + @param endAngle End of the angular range, corresponding to pos == 1. + */ + static sk_sp<SkShader> MakeSweep(SkScalar cx, SkScalar cy, + const SkColor4f colors[], sk_sp<SkColorSpace> colorSpace, + const SkScalar pos[], int count, + SkTileMode mode, + SkScalar startAngle, SkScalar endAngle, + uint32_t flags, const SkMatrix* localMatrix); + static sk_sp<SkShader> MakeSweep(SkScalar cx, SkScalar cy, + const SkColor4f colors[], sk_sp<SkColorSpace> colorSpace, + const SkScalar pos[], int count, + uint32_t flags, const SkMatrix* localMatrix) { + return MakeSweep(cx, cy, colors, std::move(colorSpace), pos, count, + SkTileMode::kClamp, 0, 360, flags, localMatrix); + } + static sk_sp<SkShader> MakeSweep(SkScalar cx, SkScalar cy, + const SkColor4f colors[], sk_sp<SkColorSpace> colorSpace, + const SkScalar pos[], int count) { + return MakeSweep(cx, cy, colors, std::move(colorSpace), pos, count, 0, nullptr); + } + + static void RegisterFlattenables(); +}; + +#endif |