/* * Copyright 2019 Google LLC * * Use of this source code is governed by a BSD-style license that can be * found in the LICENSE file. */ #ifndef SkImageFilters_DEFINED #define SkImageFilters_DEFINED #include "include/core/SkColor.h" #include "include/core/SkImage.h" #include "include/core/SkImageFilter.h" #include "include/core/SkPicture.h" #include "include/core/SkRect.h" #include "include/core/SkRefCnt.h" #include "include/core/SkScalar.h" #include "include/core/SkShader.h" #include "include/core/SkTileMode.h" #include "include/core/SkTypes.h" #include #include #include #include class SkBlender; class SkColorFilter; class SkMatrix; class SkRuntimeShaderBuilder; enum class SkBlendMode; struct SkIPoint; struct SkISize; struct SkPoint3; struct SkSamplingOptions; // A set of factory functions providing useful SkImageFilter effects. For image filters that take an // input filter, providing nullptr means it will automatically use the dynamic source image. This // source depends on how the filter is applied, but is either the contents of a saved layer when // drawing with SkCanvas, or an explicit SkImage if using one of the SkImages::MakeWithFilter // factories. class SK_API SkImageFilters { public: // This is just a convenience type to allow passing SkIRects, SkRects, and optional pointers // to those types as a crop rect for the image filter factories. It's not intended to be used // directly. struct CropRect : public std::optional { CropRect() {} // Intentionally not explicit so callers don't have to use this type but can use SkIRect or // SkRect as desired. CropRect(const SkIRect& crop) : std::optional(SkRect::Make(crop)) {} CropRect(const SkRect& crop) : std::optional(crop) {} CropRect(const std::optional& crop) : std::optional(crop) {} CropRect(const std::nullopt_t&) : std::optional() {} // Backwards compatibility for when the APIs used to explicitly accept "const SkRect*" CropRect(std::nullptr_t) {} CropRect(const SkIRect* optionalCrop) { if (optionalCrop) { *this = SkRect::Make(*optionalCrop); } } CropRect(const SkRect* optionalCrop) { if (optionalCrop) { *this = *optionalCrop; } } // std::optional doesn't define == when comparing to another optional... bool operator==(const CropRect& o) const { return this->has_value() == o.has_value() && (!this->has_value() || this->value() == *o); } }; /** * Create a filter that implements a custom blend mode. Each output pixel is the result of * combining the corresponding background and foreground pixels using the 4 coefficients: * k1 * foreground * background + k2 * foreground + k3 * background + k4 * @param k1, k2, k3, k4 The four coefficients used to combine the foreground and background. * @param enforcePMColor If true, the RGB channels will be clamped to the calculated alpha. * @param background The background content, using the source bitmap when this is null. * @param foreground The foreground content, using the source bitmap when this is null. * @param cropRect Optional rectangle that crops the inputs and output. */ static sk_sp Arithmetic(SkScalar k1, SkScalar k2, SkScalar k3, SkScalar k4, bool enforcePMColor, sk_sp background, sk_sp foreground, const CropRect& cropRect = {}); /** * This filter takes an SkBlendMode and uses it to composite the two filters together. * @param mode The blend mode that defines the compositing operation * @param background The Dst pixels used in blending, if null the source bitmap is used. * @param foreground The Src pixels used in blending, if null the source bitmap is used. * @cropRect Optional rectangle to crop input and output. */ static sk_sp Blend(SkBlendMode mode, sk_sp background, sk_sp foreground = nullptr, const CropRect& cropRect = {}); /** * This filter takes an SkBlendMode and uses it to composite the two filters together. * @param blender The blender that defines the compositing operation * @param background The Dst pixels used in blending, if null the source bitmap is used. * @param foreground The Src pixels used in blending, if null the source bitmap is used. * @cropRect Optional rectangle to crop input and output. */ static sk_sp Blend(sk_sp blender, sk_sp background, sk_sp foreground = nullptr, const CropRect& cropRect = {}); /** * Create a filter that blurs its input by the separate X and Y sigmas. The provided tile mode * is used when the blur kernel goes outside the input image. * @param sigmaX The Gaussian sigma value for blurring along the X axis. * @param sigmaY The Gaussian sigma value for blurring along the Y axis. * @param tileMode The tile mode applied at edges . * TODO (michaelludwig) - kMirror is not supported yet * @param input The input filter that is blurred, uses source bitmap if this is null. * @param cropRect Optional rectangle that crops the input and output. */ static sk_sp Blur(SkScalar sigmaX, SkScalar sigmaY, SkTileMode tileMode, sk_sp input, const CropRect& cropRect = {}); // As above, but defaults to the decal tile mode. static sk_sp Blur(SkScalar sigmaX, SkScalar sigmaY, sk_sp input, const CropRect& cropRect = {}) { return Blur(sigmaX, sigmaY, SkTileMode::kDecal, std::move(input), cropRect); } /** * Create a filter that applies the color filter to the input filter results. * @param cf The color filter that transforms the input image. * @param input The input filter, or uses the source bitmap if this is null. * @param cropRect Optional rectangle that crops the input and output. */ static sk_sp ColorFilter(sk_sp cf, sk_sp input, const CropRect& cropRect = {}); /** * Create a filter that composes 'inner' with 'outer', such that the results of 'inner' are * treated as the source bitmap passed to 'outer', i.e. result = outer(inner(source)). * @param outer The outer filter that evaluates the results of inner. * @param inner The inner filter that produces the input to outer. */ static sk_sp Compose(sk_sp outer, sk_sp inner); /** * Create a filter that applies a crop to the result of the 'input' filter. Pixels within the * crop rectangle are unmodified from what 'input' produced. Pixels outside of crop match the * provided SkTileMode (defaulting to kDecal). * * NOTE: The optional CropRect argument for many of the factories is equivalent to creating the * filter without a CropRect and then wrapping it in ::Crop(rect, kDecal). Explicitly adding * Crop filters lets you control their tiling and use different geometry for the input and the * output of another filter. * * @param rect The cropping geometry * @param tileMode The tilemode applied to pixels *outside* of 'crop' * @param input The input filter that is cropped, uses source image if this is null */ static sk_sp Crop(const SkRect& rect, SkTileMode tileMode, sk_sp input); static sk_sp Crop(const SkRect& rect, sk_sp input) { return Crop(rect, SkTileMode::kDecal, std::move(input)); } /** * Create a filter that moves each pixel in its color input based on an (x,y) vector encoded * in its displacement input filter. Two color components of the displacement image are * mapped into a vector as scale * (color[xChannel], color[yChannel]), where the channel * selectors are one of R, G, B, or A. * @param xChannelSelector RGBA channel that encodes the x displacement per pixel. * @param yChannelSelector RGBA channel that encodes the y displacement per pixel. * @param scale Scale applied to displacement extracted from image. * @param displacement The filter defining the displacement image, or null to use source. * @param color The filter providing the color pixels to be displaced. If null, * it will use the source. * @param cropRect Optional rectangle that crops the color input and output. */ static sk_sp DisplacementMap(SkColorChannel xChannelSelector, SkColorChannel yChannelSelector, SkScalar scale, sk_sp displacement, sk_sp color, const CropRect& cropRect = {}); /** * Create a filter that draws a drop shadow under the input content. This filter produces an * image that includes the inputs' content. * @param dx The X offset of the shadow. * @param dy The Y offset of the shadow. * @param sigmaX The blur radius for the shadow, along the X axis. * @param sigmaY The blur radius for the shadow, along the Y axis. * @param color The color of the drop shadow. * @param input The input filter, or will use the source bitmap if this is null. * @param cropRect Optional rectangle that crops the input and output. */ static sk_sp DropShadow(SkScalar dx, SkScalar dy, SkScalar sigmaX, SkScalar sigmaY, SkColor color, sk_sp input, const CropRect& cropRect = {}); /** * Create a filter that renders a drop shadow, in exactly the same manner as ::DropShadow, * except that the resulting image does not include the input content. This allows the shadow * and input to be composed by a filter DAG in a more flexible manner. * @param dx The X offset of the shadow. * @param dy The Y offset of the shadow. * @param sigmaX The blur radius for the shadow, along the X axis. * @param sigmaY The blur radius for the shadow, along the Y axis. * @param color The color of the drop shadow. * @param input The input filter, or will use the source bitmap if this is null. * @param cropRect Optional rectangle that crops the input and output. */ static sk_sp DropShadowOnly(SkScalar dx, SkScalar dy, SkScalar sigmaX, SkScalar sigmaY, SkColor color, sk_sp input, const CropRect& cropRect = {}); /** * Create a filter that always produces transparent black. */ static sk_sp Empty(); /** * Create a filter that draws the 'srcRect' portion of image into 'dstRect' using the given * filter quality. Similar to SkCanvas::drawImageRect. The returned image filter evaluates * to transparent black if 'image' is null. * * @param image The image that is output by the filter, subset by 'srcRect'. * @param srcRect The source pixels sampled into 'dstRect' * @param dstRect The local rectangle to draw the image into. * @param sampling The sampling to use when drawing the image. */ static sk_sp Image(sk_sp image, const SkRect& srcRect, const SkRect& dstRect, const SkSamplingOptions& sampling); /** * Create a filter that draws the image using the given sampling. * Similar to SkCanvas::drawImage. The returned image filter evaluates to transparent black if * 'image' is null. * * @param image The image that is output by the filter. * @param sampling The sampling to use when drawing the image. */ static sk_sp Image(sk_sp image, const SkSamplingOptions& sampling) { if (image) { SkRect r = SkRect::Make(image->bounds()); return Image(std::move(image), r, r, sampling); } else { return nullptr; } } /** * Create a filter that fills 'lensBounds' with a magnification of the input. * * @param lensBounds The outer bounds of the magnifier effect * @param zoomAmount The amount of magnification applied to the input image * @param inset The size or width of the fish-eye distortion around the magnified content * @param sampling The SkSamplingOptions applied to the input image when magnified * @param input The input filter that is magnified; if null the source bitmap is used * @param cropRect Optional rectangle that crops the input and output. */ static sk_sp Magnifier(const SkRect& lensBounds, SkScalar zoomAmount, SkScalar inset, const SkSamplingOptions& sampling, sk_sp input, const CropRect& cropRect = {}); /** * Create a filter that applies an NxM image processing kernel to the input image. This can be * used to produce effects such as sharpening, blurring, edge detection, etc. * @param kernelSize The kernel size in pixels, in each dimension (N by M). * @param kernel The image processing kernel. Must contain N * M elements, in row order. * @param gain A scale factor applied to each pixel after convolution. This can be * used to normalize the kernel, if it does not already sum to 1. * @param bias A bias factor added to each pixel after convolution. * @param kernelOffset An offset applied to each pixel coordinate before convolution. * This can be used to center the kernel over the image * (e.g., a 3x3 kernel should have an offset of {1, 1}). * @param tileMode How accesses outside the image are treated. * TODO (michaelludwig) - kMirror is not supported yet * @param convolveAlpha If true, all channels are convolved. If false, only the RGB channels * are convolved, and alpha is copied from the source image. * @param input The input image filter, if null the source bitmap is used instead. * @param cropRect Optional rectangle to which the output processing will be limited. */ static sk_sp MatrixConvolution(const SkISize& kernelSize, const SkScalar kernel[], SkScalar gain, SkScalar bias, const SkIPoint& kernelOffset, SkTileMode tileMode, bool convolveAlpha, sk_sp input, const CropRect& cropRect = {}); /** * Create a filter that transforms the input image by 'matrix'. This matrix transforms the * local space, which means it effectively happens prior to any transformation coming from the * SkCanvas initiating the filtering. * @param matrix The matrix to apply to the original content. * @param sampling How the image will be sampled when it is transformed * @param input The image filter to transform, or null to use the source image. */ static sk_sp MatrixTransform(const SkMatrix& matrix, const SkSamplingOptions& sampling, sk_sp input); /** * Create a filter that merges the 'count' filters together by drawing their results in order * with src-over blending. * @param filters The input filter array to merge, which must have 'count' elements. Any null * filter pointers will use the source bitmap instead. * @param count The number of input filters to be merged. * @param cropRect Optional rectangle that crops all input filters and the output. */ static sk_sp Merge(sk_sp* const filters, int count, const CropRect& cropRect = {}); /** * Create a filter that merges the results of the two filters together with src-over blending. * @param first The first input filter, or the source bitmap if this is null. * @param second The second input filter, or the source bitmap if this null. * @param cropRect Optional rectangle that crops the inputs and output. */ static sk_sp Merge(sk_sp first, sk_sp second, const CropRect& cropRect = {}) { sk_sp array[] = { std::move(first), std::move(second) }; return Merge(array, 2, cropRect); } /** * Create a filter that offsets the input filter by the given vector. * @param dx The x offset in local space that the image is shifted. * @param dy The y offset in local space that the image is shifted. * @param input The input that will be moved, if null the source bitmap is used instead. * @param cropRect Optional rectangle to crop the input and output. */ static sk_sp Offset(SkScalar dx, SkScalar dy, sk_sp input, const CropRect& cropRect = {}); /** * Create a filter that produces the SkPicture as its output, clipped to both 'targetRect' and * the picture's internal cull rect. * * If 'pic' is null, the returned image filter produces transparent black. * * @param pic The picture that is drawn for the filter output. * @param targetRect The drawing region for the picture. */ static sk_sp Picture(sk_sp pic, const SkRect& targetRect); // As above, but uses SkPicture::cullRect for the drawing region. static sk_sp Picture(sk_sp pic) { SkRect target = pic ? pic->cullRect() : SkRect::MakeEmpty(); return Picture(std::move(pic), target); } /** * Create a filter that fills the output with the per-pixel evaluation of the SkShader produced * by the SkRuntimeShaderBuilder. The shader is defined in the image filter's local coordinate * system, so it will automatically be affected by SkCanvas' transform. * * This variant assumes that the runtime shader samples 'childShaderName' with the same input * coordinate passed to to shader. * * This requires a GPU backend or SkSL to be compiled in. * * @param builder The builder used to produce the runtime shader, that will in turn * fill the result image * @param childShaderName The name of the child shader defined in the builder that will be * bound to the input param (or the source image if the input param * is null). If empty, the builder can have exactly one child shader, * which automatically binds the input param. * @param input The image filter that will be provided as input to the runtime * shader. If null the implicit source image is used instead */ static sk_sp RuntimeShader(const SkRuntimeShaderBuilder& builder, std::string_view childShaderName, sk_sp input) { return RuntimeShader(builder, /*sampleRadius=*/0.f, childShaderName, std::move(input)); } /** * As above, but 'sampleRadius' defines the sampling radius of 'childShaderName' relative to * the runtime shader produced by 'builder'. If greater than 0, the coordinate passed to * childShader.eval() will be up to 'sampleRadius' away (maximum absolute offset in 'x' or 'y') * from the coordinate passed into the runtime shader. * * This allows Skia to provide sampleable values for the image filter without worrying about * boundary conditions. * * This requires a GPU backend or SkSL to be compiled in. */ static sk_sp RuntimeShader(const SkRuntimeShaderBuilder& builder, SkScalar sampleRadius, std::string_view childShaderName, sk_sp input); /** * Create a filter that fills the output with the per-pixel evaluation of the SkShader produced * by the SkRuntimeShaderBuilder. The shader is defined in the image filter's local coordinate * system, so it will automatically be affected by SkCanvas' transform. * * This requires a GPU backend or SkSL to be compiled in. * * @param builder The builder used to produce the runtime shader, that will in turn * fill the result image * @param childShaderNames The names of the child shaders defined in the builder that will be * bound to the input params (or the source image if the input param * is null). If any name is null, or appears more than once, factory * fails and returns nullptr. * @param inputs The image filters that will be provided as input to the runtime * shader. If any are null, the implicit source image is used instead. * @param inputCount How many entries are present in 'childShaderNames' and 'inputs'. */ static sk_sp RuntimeShader(const SkRuntimeShaderBuilder& builder, std::string_view childShaderNames[], const sk_sp inputs[], int inputCount) { return RuntimeShader(builder, /*maxSampleRadius=*/0.f, childShaderNames, inputs, inputCount); } /** * As above, but 'maxSampleRadius' defines the sampling limit on coordinates provided to all * child shaders. Like the single-child variant with a sample radius, this can be used to * inform Skia that the runtime shader guarantees that all dynamic children (defined in * childShaderNames) will be evaluated with coordinates at most 'maxSampleRadius' away from the * coordinate provided to the runtime shader itself. * * This requires a GPU backend or SkSL to be compiled in. */ static sk_sp RuntimeShader(const SkRuntimeShaderBuilder& builder, SkScalar maxSampleRadius, std::string_view childShaderNames[], const sk_sp inputs[], int inputCount); enum class Dither : bool { kNo = false, kYes = true }; /** * Create a filter that fills the output with the per-pixel evaluation of the SkShader. The * shader is defined in the image filter's local coordinate system, so will automatically * be affected by SkCanvas' transform. * * Like Image() and Picture(), this is a leaf filter that can be used to introduce inputs to * a complex filter graph, but should generally be combined with a filter that as at least * one null input to use the implicit source image. * * Returns an image filter that evaluates to transparent black if 'shader' is null. * * @param shader The shader that fills the result image */ static sk_sp Shader(sk_sp shader, const CropRect& cropRect = {}) { return Shader(std::move(shader), Dither::kNo, cropRect); } static sk_sp Shader(sk_sp shader, Dither dither, const CropRect& cropRect = {}); /** * Create a tile image filter. * @param src Defines the pixels to tile * @param dst Defines the pixel region that the tiles will be drawn to * @param input The input that will be tiled, if null the source bitmap is used instead. */ static sk_sp Tile(const SkRect& src, const SkRect& dst, sk_sp input); // Morphology filter effects /** * Create a filter that dilates each input pixel's channel values to the max value within the * given radii along the x and y axes. * @param radiusX The distance to dilate along the x axis to either side of each pixel. * @param radiusY The distance to dilate along the y axis to either side of each pixel. * @param input The image filter that is dilated, using source bitmap if this is null. * @param cropRect Optional rectangle that crops the input and output. */ static sk_sp Dilate(SkScalar radiusX, SkScalar radiusY, sk_sp input, const CropRect& cropRect = {}); /** * Create a filter that erodes each input pixel's channel values to the minimum channel value * within the given radii along the x and y axes. * @param radiusX The distance to erode along the x axis to either side of each pixel. * @param radiusY The distance to erode along the y axis to either side of each pixel. * @param input The image filter that is eroded, using source bitmap if this is null. * @param cropRect Optional rectangle that crops the input and output. */ static sk_sp Erode(SkScalar radiusX, SkScalar radiusY, sk_sp input, const CropRect& cropRect = {}); // Lighting filter effects /** * Create a filter that calculates the diffuse illumination from a distant light source, * interpreting the alpha channel of the input as the height profile of the surface (to * approximate normal vectors). * @param direction The direction to the distance light. * @param lightColor The color of the diffuse light source. * @param surfaceScale Scale factor to transform from alpha values to physical height. * @param kd Diffuse reflectance coefficient. * @param input The input filter that defines surface normals (as alpha), or uses the * source bitmap when null. * @param cropRect Optional rectangle that crops the input and output. */ static sk_sp DistantLitDiffuse(const SkPoint3& direction, SkColor lightColor, SkScalar surfaceScale, SkScalar kd, sk_sp input, const CropRect& cropRect = {}); /** * Create a filter that calculates the diffuse illumination from a point light source, using * alpha channel of the input as the height profile of the surface (to approximate normal * vectors). * @param location The location of the point light. * @param lightColor The color of the diffuse light source. * @param surfaceScale Scale factor to transform from alpha values to physical height. * @param kd Diffuse reflectance coefficient. * @param input The input filter that defines surface normals (as alpha), or uses the * source bitmap when null. * @param cropRect Optional rectangle that crops the input and output. */ static sk_sp PointLitDiffuse(const SkPoint3& location, SkColor lightColor, SkScalar surfaceScale, SkScalar kd, sk_sp input, const CropRect& cropRect = {}); /** * Create a filter that calculates the diffuse illumination from a spot light source, using * alpha channel of the input as the height profile of the surface (to approximate normal * vectors). The spot light is restricted to be within 'cutoffAngle' of the vector between * the location and target. * @param location The location of the spot light. * @param target The location that the spot light is point towards * @param falloffExponent Exponential falloff parameter for illumination outside of cutoffAngle * @param cutoffAngle Maximum angle from lighting direction that receives full light * @param lightColor The color of the diffuse light source. * @param surfaceScale Scale factor to transform from alpha values to physical height. * @param kd Diffuse reflectance coefficient. * @param input The input filter that defines surface normals (as alpha), or uses the * source bitmap when null. * @param cropRect Optional rectangle that crops the input and output. */ static sk_sp SpotLitDiffuse(const SkPoint3& location, const SkPoint3& target, SkScalar falloffExponent, SkScalar cutoffAngle, SkColor lightColor, SkScalar surfaceScale, SkScalar kd, sk_sp input, const CropRect& cropRect = {}); /** * Create a filter that calculates the specular illumination from a distant light source, * interpreting the alpha channel of the input as the height profile of the surface (to * approximate normal vectors). * @param direction The direction to the distance light. * @param lightColor The color of the specular light source. * @param surfaceScale Scale factor to transform from alpha values to physical height. * @param ks Specular reflectance coefficient. * @param shininess The specular exponent determining how shiny the surface is. * @param input The input filter that defines surface normals (as alpha), or uses the * source bitmap when null. * @param cropRect Optional rectangle that crops the input and output. */ static sk_sp DistantLitSpecular(const SkPoint3& direction, SkColor lightColor, SkScalar surfaceScale, SkScalar ks, SkScalar shininess, sk_sp input, const CropRect& cropRect = {}); /** * Create a filter that calculates the specular illumination from a point light source, using * alpha channel of the input as the height profile of the surface (to approximate normal * vectors). * @param location The location of the point light. * @param lightColor The color of the specular light source. * @param surfaceScale Scale factor to transform from alpha values to physical height. * @param ks Specular reflectance coefficient. * @param shininess The specular exponent determining how shiny the surface is. * @param input The input filter that defines surface normals (as alpha), or uses the * source bitmap when null. * @param cropRect Optional rectangle that crops the input and output. */ static sk_sp PointLitSpecular(const SkPoint3& location, SkColor lightColor, SkScalar surfaceScale, SkScalar ks, SkScalar shininess, sk_sp input, const CropRect& cropRect = {}); /** * Create a filter that calculates the specular illumination from a spot light source, using * alpha channel of the input as the height profile of the surface (to approximate normal * vectors). The spot light is restricted to be within 'cutoffAngle' of the vector between * the location and target. * @param location The location of the spot light. * @param target The location that the spot light is point towards * @param falloffExponent Exponential falloff parameter for illumination outside of cutoffAngle * @param cutoffAngle Maximum angle from lighting direction that receives full light * @param lightColor The color of the specular light source. * @param surfaceScale Scale factor to transform from alpha values to physical height. * @param ks Specular reflectance coefficient. * @param shininess The specular exponent determining how shiny the surface is. * @param input The input filter that defines surface normals (as alpha), or uses the * source bitmap when null. * @param cropRect Optional rectangle that crops the input and output. */ static sk_sp SpotLitSpecular(const SkPoint3& location, const SkPoint3& target, SkScalar falloffExponent, SkScalar cutoffAngle, SkColor lightColor, SkScalar surfaceScale, SkScalar ks, SkScalar shininess, sk_sp input, const CropRect& cropRect = {}); private: SkImageFilters() = delete; }; #endif // SkImageFilters_DEFINED