1 /* 2 * Copyright 2006 The Android Open Source Project 3 * 4 * Use of this source code is governed by a BSD-style license that can be 5 * found in the LICENSE file. 6 */ 7 8 #ifndef SkBlurMask_DEFINED 9 #define SkBlurMask_DEFINED 10 11 #include "include/core/SkScalar.h" 12 #include "include/core/SkTypes.h" 13 #include "src/core/SkMask.h" 14 15 #include <cstdint> 16 17 class SkRRect; 18 enum SkBlurStyle : int; 19 struct SkIPoint; 20 struct SkRect; 21 22 class SkBlurMask { 23 public: 24 [[nodiscard]] static bool BlurRect(SkScalar sigma, SkMaskBuilder *dst, const SkRect &src, 25 SkBlurStyle, SkIPoint *margin = nullptr, 26 SkMaskBuilder::CreateMode createMode = 27 SkMaskBuilder::kComputeBoundsAndRenderImage_CreateMode); 28 [[nodiscard]] static bool BlurRRect(SkScalar sigma, SkMaskBuilder *dst, const SkRRect &src, 29 SkBlurStyle, SkIPoint *margin = nullptr, 30 SkMaskBuilder::CreateMode createMode = 31 SkMaskBuilder::kComputeBoundsAndRenderImage_CreateMode); 32 33 // forceQuality will prevent BoxBlur from falling back to the low quality approach when sigma 34 // is very small -- this can be used predict the margin bump ahead of time without completely 35 // replicating the internal logic. This permits not only simpler caching of blurred results, 36 // but also being able to predict precisely at what pixels the blurred profile of e.g. a 37 // rectangle will lie. 38 // 39 // Calling details: 40 // * calculate margin - if src.fImage is null, then this call only calculates the border. 41 // * failure - if src.fImage is not null, failure is signal with dst->fImage being 42 // null. 43 44 [[nodiscard]] static bool BoxBlur(SkMaskBuilder* dst, const SkMask& src, 45 SkScalar sigma, SkBlurStyle style, 46 SkIPoint* margin = nullptr); 47 48 // the "ground truth" blur does a gaussian convolution; it's slow 49 // but useful for comparison purposes. 50 [[nodiscard]] static bool BlurGroundTruth(SkScalar sigma, SkMaskBuilder* dst, 51 const SkMask& src, 52 SkBlurStyle, SkIPoint* margin = nullptr); 53 54 // If radius > 0, return the corresponding sigma, else return 0 55 static SkScalar SK_SPI ConvertRadiusToSigma(SkScalar radius); 56 // If sigma > 0.5, return the corresponding radius, else return 0 57 static SkScalar SK_SPI ConvertSigmaToRadius(SkScalar sigma); 58 59 /* Helper functions for analytic rectangle blurs */ 60 61 /** Look up the intensity of the (one dimnensional) blurred half-plane. 62 @param profile The precomputed 1D blur profile; initialized by ComputeBlurProfile below. 63 @param loc the location to look up; The lookup will clamp invalid inputs, but 64 meaningful data are available between 0 and blurred_width 65 @param blurred_width The width of the final, blurred rectangle 66 @param sharp_width The width of the original, unblurred rectangle. 67 */ 68 static uint8_t ProfileLookup(const uint8_t* profile, int loc, int blurredWidth, int sharpWidth); 69 70 /** Populate the profile of a 1D blurred halfplane. 71 @param profile The 1D table to fill in 72 @param size Should be 6*sigma bytes 73 @param sigma The standard deviation of the gaussian blur kernel 74 */ 75 static void ComputeBlurProfile(uint8_t* profile, int size, SkScalar sigma); 76 77 /** Compute an entire scanline of a blurred step function. This is a 1D helper that 78 will produce both the horizontal and vertical profiles of the blurry rectangle. 79 @param pixels Location to store the resulting pixel data; allocated and managed by caller 80 @param profile Precomputed blur profile computed by ComputeBlurProfile above. 81 @param width Size of the pixels array. 82 @param sigma Standard deviation of the gaussian blur kernel used to compute the profile; 83 this implicitly gives the size of the pixels array. 84 */ 85 86 static void ComputeBlurredScanline(uint8_t* pixels, const uint8_t* profile, 87 unsigned int width, SkScalar sigma); 88 }; 89 90 #endif 91