/**************************************************************************** * * otsvg.h * * Interface for OT-SVG support related things (specification). * * Copyright (C) 2004-2019 by * David Turner, Robert Wilhelm, Werner Lemberg and Moazin Khatti. * * This file is part of the FreeType project, and may only be used, * modified, and distributed under the terms of the FreeType project * license, LICENSE.TXT. By continuing to use, modify, or distribute * this file you indicate that you have read the license and * understand and accept it fully. * */ #ifndef FTSVG_RENDERER_H_ #define FTSVG_RENDERER_H_ #include #include FT_FREETYPE_H #ifdef FREETYPE_H #error "freetype.h of FreeType 1 has been loaded!" #error "Please fix the directory search order for header files" #error "so that freetype.h of FreeType 2 is found first." #endif FT_BEGIN_HEADER /************************************************************************** * * @functype: * SVG_Lib_Init_Func * * @description: * A callback which is called when the first OT-SVG glyph is rendered in * the lifetime of an @FT_Library object. The callback should perform all * sorts of initializations that the SVG rendering library needs such as * allocating memory for `svg_renderer_state` of @FT_LibraryRec. * * @input: * library :: * An instance of @FT_Library. It's passed to give the callbacks access * to `svg_renderer_state` of @FT_LibraryRec. * * @return: * FreeType error code. 0 means success. */ typedef FT_Error (*SVG_Lib_Init_Func)( FT_Library library ); /************************************************************************** * * @functype: * SVG_Lib_Free_Func * * @description: * A callback which is called when the `ot-svg` module is being freed. * It is only called only if the init hook was called earlier. So, if no * OT-SVG glyph is rendered, neither the init hook is called nor the free * hook. * * @input: * library :: * An instance of @FT_Library. It's passed to give the callbacks access * to `svg_renderer_state` of @FT_LibraryRec. */ typedef void (*SVG_Lib_Free_Func)( FT_Library library ); /************************************************************************** * * @functype: * SVG_Lib_Render_Func * * @description: * A callback which is called to render an OT-SVG glyph. This callback * hook is called right after the preset hook has been called with * `cache` set to `TRUE`. The data necessary to render is available * through the handle @FT_SVG_Document which is set in `other` field of * @FT_GlyphSlotRec. * * @input: * slot :: * The slot to render. * * @return: * FreeType error code. 0 means success. */ typedef FT_Error (*SVG_Lib_Render_Func)( FT_GlyphSlot slot ); /************************************************************************** * * @functype: * SVG_Lib_Preset_Slot_Func * * @description: * A callback which is called to preset the glyphslot. It is called from * two places. * * 1. When `FT_Load_Glyph` needs to preset the glyphslot. * 2. Right before the `ot-svg` module calls the render callback hook. * * When it is the former, the argument `cache` is set to `FALSE`. When it * is the latter, the argument `cache` is set to `TRUE`. This distinction * has been made because while presetting a glyphslot many calculations * are needed and later the render callback hook needs the same * calculations, thus, if `cache` is `TRUE`, the hook might _cache_ these * calculations in `svg_renderer_state` of @FT_LibraryRec. * * @input: * slot :: * The glyph slot which has the SVG document loaded. * * cache :: * See description. * * @return: * FreeType error code. 0 means success. */ typedef FT_Error (*SVG_Lib_Preset_Slot_Func)( FT_GlyphSlot slot, FT_Bool cache); /************************************************************************** * * @struct: * SVG_RendererHooks * * @description: * A structure that stores the four hooks needed to render OT-SVG glyphs * properly. The structure is publicly used to set the hooks via driver * properties. * * @fields: * init_svg :: * The initialization hook. * * free_svg :: * The cleanup hook. * * render_hook :: * The render hook. * * preset_slot :: * The preset hook. */ typedef struct SVG_RendererHooks_ { SVG_Lib_Init_Func init_svg; SVG_Lib_Free_Func free_svg; SVG_Lib_Render_Func render_svg; SVG_Lib_Preset_Slot_Func preset_slot; } SVG_RendererHooks; /************************************************************************** * * @struct: * FT_SVG_DocumentRec_ * * @description: * A structure that models one SVG document. * * @fields: * svg_document :: * A pointer to the SVG document. * * svg_document_length :: * The length of `svg_document`. * * metrics :: * A metrics object storing the size information. * * units_per_EM :: * The size of the EM square. * * start_glyph_id :: * The first glyph ID in the glyph range is covered by this document. * * end_glyph_id :: * The last glyph ID in the glyph range is covered by this document. * * transform :: * A 2x2 transformation matrix to apply on the glyph while rendering it. * * delta :: * Translation to apply on the glyph while rendering. * * @note: * `metrics` and `units_per_EM` might look like repetitions since both * fields are stored in face object, but they are not; When the slot is * passed down to a renderer, the renderer can only access the `metrics` * and `units_per_EM` by `slot->face`. However, when `FT_Glyph_To_Bitmap` * sets up a dummy object, it has no way to set a `face` object. Thus, * metrics information and units_per_EM (which is necessary for OT-SVG) * has to be stored separately. */ typedef struct FT_SVG_DocumentRec_ { FT_Byte* svg_document; FT_ULong svg_document_length; FT_Size_Metrics metrics; FT_UShort units_per_EM; FT_UShort start_glyph_id; FT_UShort end_glyph_id; FT_Matrix transform; FT_Vector delta; } FT_SVG_DocumentRec; /************************************************************************** * * @type: * FT_SVG_Document * * @description: * A handle to a FT_SVG_DocumentRec object. */ typedef struct FT_SVG_DocumentRec_* FT_SVG_Document; FT_END_HEADER #endif