ftsdfrend.h (3386B)
1 /**************************************************************************** 2 * 3 * ftsdfrend.h 4 * 5 * Signed Distance Field renderer interface (specification). 6 * 7 * Copyright (C) 2020-2025 by 8 * David Turner, Robert Wilhelm, and Werner Lemberg. 9 * 10 * Written by Anuj Verma. 11 * 12 * This file is part of the FreeType project, and may only be used, 13 * modified, and distributed under the terms of the FreeType project 14 * license, LICENSE.TXT. By continuing to use, modify, or distribute 15 * this file you indicate that you have read the license and 16 * understand and accept it fully. 17 * 18 */ 19 20 21 #ifndef FTSDFREND_H_ 22 #define FTSDFREND_H_ 23 24 #include <freetype/ftrender.h> 25 #include <freetype/ftmodapi.h> 26 #include <freetype/internal/ftobjs.h> 27 28 FT_BEGIN_HEADER 29 30 31 /************************************************************************** 32 * 33 * @struct: 34 * SDF_Renderer_Module 35 * 36 * @description: 37 * This struct extends the native renderer struct `FT_RendererRec`. It 38 * is basically used to store various parameters required by the 39 * renderer and some additional parameters that can be used to tweak the 40 * output of the renderer. 41 * 42 * @fields: 43 * root :: 44 * The native rendere struct. 45 * 46 * spread :: 47 * This is an essential parameter/property required by the renderer. 48 * `spread` defines the maximum unsigned value that is present in the 49 * final SDF output. For the default value check file 50 * `ftsdfcommon.h`. 51 * 52 * flip_sign :: 53 * By default positive values indicate positions inside of contours, 54 * i.e., filled by a contour. If this property is true then that 55 * output will be the opposite of the default, i.e., negative values 56 * indicate positions inside of contours. 57 * 58 * flip_y :: 59 * Setting this parameter to true makes the output image flipped 60 * along the y-axis. 61 * 62 * overlaps :: 63 * Set this to true to generate SDF for glyphs having overlapping 64 * contours. The overlapping support is limited to glyphs that do not 65 * have self-intersecting contours. Also, removing overlaps require a 66 * considerable amount of extra memory; additionally, it will not work 67 * if generating SDF from bitmap. 68 * 69 * @note: 70 * All properties except `overlaps` are valid for both the 'sdf' and 71 * 'bsdf' renderers. 72 * 73 */ 74 typedef struct SDF_Renderer_Module_ 75 { 76 FT_RendererRec root; 77 FT_UInt spread; 78 FT_Bool flip_sign; 79 FT_Bool flip_y; 80 FT_Bool overlaps; 81 82 } SDF_Renderer_Module, *SDF_Renderer; 83 84 85 /************************************************************************** 86 * 87 * @renderer: 88 * ft_sdf_renderer_class 89 * 90 * @description: 91 * Renderer to convert @FT_Outline to signed distance fields. 92 * 93 */ 94 FT_DECLARE_RENDERER( ft_sdf_renderer_class ) 95 96 97 /************************************************************************** 98 * 99 * @renderer: 100 * ft_bitmap_sdf_renderer_class 101 * 102 * @description: 103 * This is not exactly a renderer; it is just a converter that 104 * transforms bitmaps to signed distance fields. 105 * 106 * @note: 107 * This is not a separate module, it is part of the 'sdf' module. 108 * 109 */ 110 FT_DECLARE_RENDERER( ft_bitmap_sdf_renderer_class ) 111 112 113 FT_END_HEADER 114 115 #endif /* FTSDFREND_H_ */ 116 117 118 /* END */