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 BlurRect(SkScalar sigma, SkMask *dst, const SkRect &src, SkBlurStyle, 19 SkIPoint *margin = NULL, 20 SkMask::CreateMode createMode = 21 SkMask::kComputeBoundsAndRenderImage_CreateMode); 22 static bool BlurRRect(SkScalar sigma, SkMask *dst, const SkRRect &src, SkBlurStyle, 23 SkIPoint *margin = NULL, 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 BoxBlur(SkMask* dst, const SkMask& src, 34 SkScalar sigma, SkBlurStyle style, SkBlurQuality quality, 35 SkIPoint* margin = NULL, bool force_quality=false); 36 37 // the "ground truth" blur does a gaussian convolution; it's slow 38 // but useful for comparison purposes. 39 static bool BlurGroundTruth(SkScalar sigma, SkMask* dst, const SkMask& src, SkBlurStyle, 40 SkIPoint* margin = NULL); 41 42 // If radius > 0, return the corresponding sigma, else return 0 43 static SkScalar ConvertRadiusToSigma(SkScalar radius); 44 // If sigma > 0.5, return the corresponding radius, else return 0 45 static SkScalar ConvertSigmaToRadius(SkScalar sigma); 46 47 /* Helper functions for analytic rectangle blurs */ 48 49 /** Look up the intensity of the (one dimnensional) blurred half-plane. 50 @param profile The precomputed 1D blur profile; memory allocated by and managed by 51 ComputeBlurProfile below. 52 @param loc the location to look up; The lookup will clamp invalid inputs, but 53 meaningful data are available between 0 and blurred_width 54 @param blurred_width The width of the final, blurred rectangle 55 @param sharp_width The width of the original, unblurred rectangle. 56 */ 57 static uint8_t ProfileLookup(const uint8_t* profile, int loc, int blurred_width, int sharp_width); 58 59 /** Allocate memory for and populate the profile of a 1D blurred halfplane. The caller 60 must free the memory. The amount of memory allocated will be exactly 6*sigma bytes. 61 @param sigma The standard deviation of the gaussian blur kernel 62 @param profile_out The location to store the allocated profile curve 63 */ 64 65 static void ComputeBlurProfile(SkScalar sigma, uint8_t** profile_out); 66 67 /** Compute an entire scanline of a blurred step function. This is a 1D helper that 68 will produce both the horizontal and vertical profiles of the blurry rectangle. 69 @param pixels Location to store the resulting pixel data; allocated and managed by caller 70 @param profile Precomputed blur profile computed by ComputeBlurProfile above. 71 @param width Size of the pixels array. 72 @param sigma Standard deviation of the gaussian blur kernel used to compute the profile; 73 this implicitly gives the size of the pixels array. 74 */ 75 76 static void ComputeBlurredScanline(uint8_t* pixels, const uint8_t* profile, 77 unsigned int width, SkScalar sigma); 78 79 80 81 }; 82 83 #endif 84