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 "SkBlurTypes.h" 12 #include "SkShader.h" 13 #include "SkMask.h" 14 #include "SkRRect.h" 15 16 class SkBlurMask { 17 public: 18 static bool SK_WARN_UNUSED_RESULT BlurRect(SkScalar sigma, SkMask *dst, const SkRect &src, 19 SkBlurStyle, SkIPoint *margin = nullptr, 20 SkMask::CreateMode createMode = 21 SkMask::kComputeBoundsAndRenderImage_CreateMode); 22 static bool SK_WARN_UNUSED_RESULT BlurRRect(SkScalar sigma, SkMask *dst, const SkRRect &src, 23 SkBlurStyle, SkIPoint *margin = nullptr, 24 SkMask::CreateMode createMode = 25 SkMask::kComputeBoundsAndRenderImage_CreateMode); 26 27 // forceQuality will prevent BoxBlur from falling back to the low quality approach when sigma 28 // is very small -- this can be used predict the margin bump ahead of time without completely 29 // replicating the internal logic. This permits not only simpler caching of blurred results, 30 // but also being able to predict precisely at what pixels the blurred profile of e.g. a 31 // rectangle will lie. 32 33 static bool SK_WARN_UNUSED_RESULT BoxBlur(SkMask* dst, const SkMask& src, 34 SkScalar sigma, SkBlurStyle style, SkBlurQuality, 35 SkIPoint* margin = nullptr, 36 bool forceQuality = false); 37 38 // the "ground truth" blur does a gaussian convolution; it's slow 39 // but useful for comparison purposes. 40 static bool SK_WARN_UNUSED_RESULT BlurGroundTruth(SkScalar sigma, SkMask* dst, 41 const SkMask& src, 42 SkBlurStyle, SkIPoint* margin = nullptr); 43 44 // If radius > 0, return the corresponding sigma, else return 0 45 static SkScalar ConvertRadiusToSigma(SkScalar radius); 46 // If sigma > 0.5, return the corresponding radius, else return 0 47 static SkScalar ConvertSigmaToRadius(SkScalar sigma); 48 49 /* Helper functions for analytic rectangle blurs */ 50 51 /** Look up the intensity of the (one dimnensional) blurred half-plane. 52 @param profile The precomputed 1D blur profile; memory allocated by and managed by 53 ComputeBlurProfile below. 54 @param loc the location to look up; The lookup will clamp invalid inputs, but 55 meaningful data are available between 0 and blurred_width 56 @param blurred_width The width of the final, blurred rectangle 57 @param sharp_width The width of the original, unblurred rectangle. 58 */ 59 static uint8_t ProfileLookup(const uint8_t* profile, int loc, int blurredWidth, int sharpWidth); 60 61 /** Allocate memory for and populate the profile of a 1D blurred halfplane. The caller 62 must free the memory. The amount of memory allocated will be exactly 6*sigma bytes. 63 @param sigma The standard deviation of the gaussian blur kernel 64 */ 65 66 static uint8_t* ComputeBlurProfile(SkScalar sigma); 67 68 /** Compute an entire scanline of a blurred step function. This is a 1D helper that 69 will produce both the horizontal and vertical profiles of the blurry rectangle. 70 @param pixels Location to store the resulting pixel data; allocated and managed by caller 71 @param profile Precomputed blur profile computed by ComputeBlurProfile above. 72 @param width Size of the pixels array. 73 @param sigma Standard deviation of the gaussian blur kernel used to compute the profile; 74 this implicitly gives the size of the pixels array. 75 */ 76 77 static void ComputeBlurredScanline(uint8_t* pixels, const uint8_t* profile, 78 unsigned int width, SkScalar sigma); 79 80 81 82 }; 83 84 #endif 85