261 lines
7.3 KiB
C
261 lines
7.3 KiB
C
/****************************************************************************
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*
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* ttsvg.c
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*
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* OpenType SVG Color (specification).
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*
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* Copyright (C) 2018-2019 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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/**************************************************************************
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*
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* `SVG' table specification:
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*
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* https://docs.microsoft.com/en-us/typography/opentype/spec/svg
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*
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*/
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#include <ft2build.h>
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#include FT_INTERNAL_STREAM_H
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#include FT_INTERNAL_OBJECTS_H
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#include FT_TRUETYPE_TAGS_H
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#include FT_GZIP_H
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#include FT_SVG_RENDER_H
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#ifdef FT_CONFIG_OPTION_SVG
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#include "ttsvg.h"
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/* TODO: (OT-SVG) Decide whether to add documentation here or not */
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typedef struct Svg_
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{
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FT_UShort version; /* Table version (starting at 0) */
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FT_UShort num_entries; /* Number of SVG document records */
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/* Pointer to the starting of SVG Document List */
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FT_Byte* svg_doc_list;
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/* Memory that backs up SVG */
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void* table;
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FT_ULong table_size;
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} Svg;
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FT_LOCAL_DEF( FT_Error )
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tt_face_load_svg( TT_Face face,
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FT_Stream stream )
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{
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FT_Error error;
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FT_Memory memory = face->root.memory;
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FT_ULong table_size;
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FT_Byte* table = NULL;
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FT_Byte* p = NULL;
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Svg* svg = NULL;
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FT_ULong offsetToSVGDocumentList;
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error = face->goto_table( face, TTAG_SVG, stream, &table_size );
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if( error )
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goto NoSVG;
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if( FT_FRAME_EXTRACT( table_size, table ))
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goto NoSVG;
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/* Allocate the memory for the Svg object */
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if( FT_NEW( svg ) )
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goto NoSVG;
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p = table;
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svg->version = FT_NEXT_USHORT( p );
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offsetToSVGDocumentList = FT_NEXT_ULONG( p );
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if( offsetToSVGDocumentList == 0 )
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goto InvalidTable;
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svg->svg_doc_list = (FT_Byte*)( table + offsetToSVGDocumentList );
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p = svg->svg_doc_list;
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svg->num_entries = FT_NEXT_USHORT( p );
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svg->table = table;
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svg->table_size = table_size;
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face->svg = svg;
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face->root.face_flags |= FT_FACE_FLAG_SVG;
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return FT_Err_Ok;
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InvalidTable:
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error = FT_THROW( Invalid_Table );
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NoSVG:
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FT_FRAME_RELEASE( table );
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FT_FREE( svg );
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face->svg = NULL;
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return error;
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}
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FT_LOCAL_DEF( void )
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tt_face_free_svg( TT_Face face )
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{
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FT_Memory memory = face->root.memory;
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FT_Stream stream = face->root.stream;
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Svg* svg = (Svg*) face->svg;
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if( svg )
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{
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FT_FRAME_RELEASE( svg->table );
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FT_FREE( svg );
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}
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}
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FT_Error
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find_doc( FT_Byte* stream,
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FT_UShort num_entries,
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FT_UInt glyph_index,
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FT_ULong *doc_offset,
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FT_ULong *doc_length,
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FT_UShort *start_glyph,
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FT_UShort *end_glyph )
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{
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FT_Error error;
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FT_UShort start_glyph_id;
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FT_UShort end_glyph_id;
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FT_ULong cur_doc_offset;
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FT_ULong cur_doc_length;
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FT_Bool found = FALSE;
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FT_UInt i = 0;
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/* TODO: (OT-SVG) Convert to efficient search algorithm */
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/* TODO: (OT-SVG) Use Frame Fields here instead of `FT_NEXT_*' */
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for ( i = 0; i < num_entries; i++)
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{
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start_glyph_id = FT_NEXT_USHORT( stream );
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end_glyph_id = FT_NEXT_USHORT( stream );
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cur_doc_offset = FT_NEXT_ULONG( stream );
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cur_doc_length = FT_NEXT_ULONG( stream );
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if ( ( glyph_index >= start_glyph_id) &&
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( glyph_index <= end_glyph_id ) )
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{
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found = TRUE;
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*doc_offset = cur_doc_offset;
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*doc_length = cur_doc_length;
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break;
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}
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}
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if ( found != TRUE )
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error = FT_THROW( Invalid_Glyph_Index );
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else
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{
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*start_glyph = start_glyph_id;
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*end_glyph = end_glyph_id;
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error = FT_Err_Ok;
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}
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return error;
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}
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FT_LOCAL_DEF(FT_Error)
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tt_face_load_svg_doc( FT_GlyphSlot glyph,
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FT_UInt glyph_index )
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{
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/* TODO: (OT-SVG) properly clean stuff here on errors */
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FT_Byte* doc_list; /* Pointer to the Svg Document List */
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FT_UShort num_entries; /* Total no of entires in doc list */
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FT_ULong doc_offset;
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FT_ULong doc_length;
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FT_UShort start_glyph_id;
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FT_UShort end_glyph_id;
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FT_ULong uncomp_size;
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FT_Byte* uncomp_buffer;
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FT_Error error = FT_Err_Ok;
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TT_Face face = (TT_Face)glyph->face;
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FT_Memory memory = face->root.memory;
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Svg* svg = face->svg;
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FT_SVG_Document svg_document = glyph->other;
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/* handle svg being 0x0 situation here */
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doc_list = svg->svg_doc_list;
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num_entries = FT_NEXT_USHORT( doc_list );
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error = find_doc( doc_list, num_entries, glyph_index,
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&doc_offset, &doc_length,
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&start_glyph_id, &end_glyph_id );
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if ( error != FT_Err_Ok )
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return error;
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doc_list = svg->svg_doc_list; /* Reset to so we can use it again */
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doc_list = (FT_Byte*)( doc_list + doc_offset );
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if( ( doc_list[0] == 0x1F ) && ( doc_list[1] == 0x8B )
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&& ( doc_list[2] == 0x08 ) )
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{
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/* get the size of the orignal document. This helps in alotting the
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* buffer to accomodate the uncompressed version. The last 4 bytes
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* of the compressed document are equal to orignal_size modulo 2^32.
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* Since SVG docs will be lesser in size then 2^32, we can use this
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* accurately. The four bytes are stored in little-endian format.
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*/
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uncomp_size = (FT_ULong)doc_list[doc_length - 1] << 24 |
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(FT_ULong)doc_list[doc_length - 2] << 16 |
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(FT_ULong)doc_list[doc_length - 3] << 8 |
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(FT_ULong)doc_list[doc_length - 4];
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uncomp_buffer = (FT_Byte*) memory->alloc(memory, uncomp_size);
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glyph->internal->flags |= FT_GLYPH_OWN_GZIP_SVG;
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error = FT_Gzip_Uncompress( memory, uncomp_buffer, &uncomp_size,
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doc_list, doc_length );
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if ( error != FT_Err_Ok )
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{
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error = FT_THROW( Invalid_Table );
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return error;
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}
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doc_list = uncomp_buffer;
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doc_length = uncomp_size;
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}
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svg_document->svg_document = doc_list;
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svg_document->svg_document_length = doc_length;
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svg_document->metrics = glyph->face->size->metrics;
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svg_document->units_per_EM = glyph->face->units_per_EM;
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svg_document->start_glyph_id = start_glyph_id;
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svg_document->end_glyph_id = end_glyph_id;
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glyph->other = svg_document;
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glyph->metrics.horiAdvance *= ((float)glyph->face->size->metrics.x_ppem)/
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((float)glyph->face->units_per_EM) * 64.0;
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glyph->metrics.vertAdvance *= ((float)glyph->face->size->metrics.y_ppem)/
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((float)glyph->face->units_per_EM) * 64.0;
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return FT_Err_Ok;
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}
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#else /* !FT_CONFIG_OPTION_SVG */
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/* ANSI C doesn't like empty source files */
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typedef int _tt_cpal_dummy;
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#endif /* !FT_CONFIG_OPTION_SVG */
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