197 lines
5.5 KiB
C
197 lines
5.5 KiB
C
/****************************************************************************
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*
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* svgrenderer.h
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*
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* Interface for SVG Renderer Module (specification).
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*
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* Copyright (C) 2004-2019 by
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* David Turner, Robert Wilhelm, Werner Lemberg and Moazin Khatti.
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*
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* This file is part of the FreeType project, and may only be used,
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* modified, and distributed under the terms of the FreeType project
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* license, LICENSE.TXT. By continuing to use, modify, or distribute
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* this file you indicate that you have read the license and
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* understand and accept it fully.
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*
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*/
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#ifndef FTSVG_RENDERER_H_
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#define FTSVG_RENDERER_H_
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#include <ft2build.h>
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#include FT_FREETYPE_H
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#ifdef FREETYPE_H
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#error "freetype.h of FreeType 1 has been loaded!"
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#error "Please fix the directory search order for header files"
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#error "so that freetype.h of FreeType 2 is found first."
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#endif
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FT_BEGIN_HEADER
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/**************************************************************************
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*
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* @functype:
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* SVG_Lib_Init_Func
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*
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* @description:
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* A callback used to initiate the SVG Rendering port
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*
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* @input:
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* library ::
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* A instance of library. This is required to initialize the
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* renderer's state which will be held in the library.
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*
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* @return:
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* FreeType error code. 0 means success.
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*/
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typedef FT_Error
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(*SVG_Lib_Init_Func)( FT_Library library );
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/**************************************************************************
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*
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* @functype:
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* SVG_Lib_Free_Func
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*
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* @description:
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* A callback used to free the SVG Rendering port. Calling this callback
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* shall do all cleanups that the SVG Rendering port wants to do.
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*
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* @input:
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* library ::
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* A instance of library. This is required to free the renderer's
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* state which will be held in the library.
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*/
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typedef void
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(*SVG_Lib_Free_Func)( FT_Library library );
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/**************************************************************************
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*
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* @functype:
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* SVG_Lib_Render_Func
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*
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* @description:
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* A callback used to render the glyph loaded in the slot.
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*
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* @input:
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* slot ::
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* The whole glyph slot object.
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*
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* outline_bbox ::
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* The bounding box of the glyph in font units. So that the renderer
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* may not need to calculate it again.
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*
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* @return:
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* FreeType error code. 0 means success.
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*/
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typedef FT_Error
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(*SVG_Lib_Render_Func)( FT_GlyphSlot slot,
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FT_BBox outline_bbox);
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/**************************************************************************
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*
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* @functype:
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* SVG_Lib_Get_Buffer_Size_Func
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*
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* @description:
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* A callback which is called to get the size of the image buffer needed.
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* This buffer will ultimately be populated by `SVG_Lib_Render_Func`
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* hook.
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*
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* @input:
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* slot ::
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* The glyph slot which has the SVG document loaded as well as other
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* info.
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*
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* bbox ::
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* The bbox in font units. This is required for the rendering port to
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* predict the final size of the image buffer.
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*
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* @return:
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* Size of the state structure in bytes.
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*/
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typedef FT_ULong
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(*SVG_Lib_Get_Buffer_Size_Func)( FT_GlyphSlot slot,
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FT_BBox bbox );
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typedef struct SVG_RendererHooks_
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{
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/* Api Hooks for OT-SVG Rendering */
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SVG_Lib_Init_Func init_svg;
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SVG_Lib_Free_Func free_svg;
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SVG_Lib_Render_Func render_svg;
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SVG_Lib_Get_Buffer_Size_Func get_buffer_size;
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} SVG_RendererHooks;
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/**************************************************************************
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*
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* @struct:
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* FT_SVG_DocumentRec_
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*
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* @description:
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* A structure that models one SVG document.
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*
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* @fields:
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* svg_document ::
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* A pointer to the SVG document string.
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*
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* svg_document_length ::
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* The length of the SVG document string.
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*
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* metrics ::
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* A metrics object storing the size information.
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*
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* units_per_EM ::
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* The size of the EM square.
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*
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* start_glyph_id ::
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* The starting glyph ID for the glyph range that this document has.
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*
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* end_glyph_id ::
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* The ending glyph ID for the glyph range that this document has.
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*
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* @note:
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* `metrics` and `units_per_EM` might look like repetitions since both
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* fields are stored in face objects. However, the Glyph Management API
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* requires an `FT_Glyph` to store all the information that completely
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* describes a glyph. Outline glyphs are themselves scaled thus they
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* don`t need this information. However, SVG documents do. The field
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* of `units_per_EM` is needed because the SVG is to be scaled in case
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* its viewbox size differs from `units_per_EM`. For more info, refer
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* to the section `Coordinate Systems and Glyph Metrics` of the OpenType
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* SVG specs.
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*/
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typedef struct FT_SVG_DocumentRec_
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{
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FT_Byte* svg_document;
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FT_ULong svg_document_length;
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FT_Size_Metrics metrics;
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FT_UShort units_per_EM;
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FT_UShort start_glyph_id;
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FT_UShort end_glyph_id;
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/* TODO: (OT-SVG) Not storing glyph_index here for now. Might need to
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* at some point. Review this! */
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} FT_SVG_DocumentRec;
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/**************************************************************************
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*
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* @type:
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* FT_SVG_Document
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*
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* @description:
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* A handle to a FT_SVG_DocumentRec object.
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*/
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typedef struct FT_SVG_DocumentRec_* FT_SVG_Document;
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FT_END_HEADER
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#endif
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