ref: 21d0fa374200aecc6605daf034a47167ea82ed6f
dir: /src/sfnt/ttsvg.c/
/****************************************************************************
*
* ttsvg.c
*
* OpenType SVG Color (specification).
*
* Copyright (C) 2022 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.
*
*/
/**************************************************************************
*
* 'SVG' table specification:
*
* https://docs.microsoft.com/en-us/typography/opentype/spec/svg
*
*/
#include <ft2build.h>
#include <freetype/internal/ftstream.h>
#include <freetype/internal/ftobjs.h>
#include <freetype/internal/ftdebug.h>
#include <freetype/tttags.h>
#include <freetype/ftgzip.h>
#include <freetype/otsvg.h>
#ifdef FT_CONFIG_OPTION_SVG
#include "ttsvg.h"
/* NOTE: These table sizes are given by the specification. */
#define SVG_TABLE_HEADER_SIZE 10U
#define SVG_DOCUMENT_RECORD_SIZE 12U
#define SVG_DOCUMENT_LIST_MINIMUM_SIZE 2U + SVG_DOCUMENT_RECORD_SIZE
#define SVG_MINIMUM_SIZE SVG_TABLE_HEADER_SIZE + \
SVG_DOCUMENT_LIST_MINIMUM_SIZE
typedef struct Svg_
{
FT_UShort version; /* table version (starting at 0) */
FT_UShort num_entries; /* number of SVG document records */
FT_Byte* svg_doc_list; /* pointer to the start of SVG Document List */
void* table; /* memory that backs up SVG */
FT_ULong table_size;
} Svg;
/**************************************************************************
*
* The macro FT_COMPONENT is used in trace mode. It is an implicit
* parameter of the FT_TRACE() and FT_ERROR() macros, usued to print/log
* messages during execution.
*/
#undef FT_COMPONENT
#define FT_COMPONENT ttsvg
FT_LOCAL_DEF( FT_Error )
tt_face_load_svg( TT_Face face,
FT_Stream stream )
{
FT_Error error;
FT_Memory memory = face->root.memory;
FT_ULong table_size;
FT_Byte* table = NULL;
FT_Byte* p = NULL;
Svg* svg = NULL;
FT_ULong offsetToSVGDocumentList;
error = face->goto_table( face, TTAG_SVG, stream, &table_size );
if ( error )
goto NoSVG;
if ( table_size < SVG_MINIMUM_SIZE )
goto InvalidTable;
if ( FT_FRAME_EXTRACT( table_size, table ) )
goto NoSVG;
/* Allocate memory for the SVG object */
if ( FT_NEW( svg ) )
goto NoSVG;
p = table;
svg->version = FT_NEXT_USHORT( p );
offsetToSVGDocumentList = FT_NEXT_ULONG( p );
if ( offsetToSVGDocumentList < SVG_TABLE_HEADER_SIZE ||
offsetToSVGDocumentList > table_size -
SVG_DOCUMENT_LIST_MINIMUM_SIZE )
goto InvalidTable;
svg->svg_doc_list = (FT_Byte*)( table + offsetToSVGDocumentList );
p = svg->svg_doc_list;
svg->num_entries = FT_NEXT_USHORT( p );
FT_TRACE3(( "version: %d\n", svg->version ));
FT_TRACE3(( "number of entries: %d\n", svg->num_entries ));
if ( offsetToSVGDocumentList +
svg->num_entries * SVG_DOCUMENT_RECORD_SIZE > table_size )
goto InvalidTable;
svg->table = table;
svg->table_size = table_size;
face->svg = svg;
face->root.face_flags |= FT_FACE_FLAG_SVG;
return FT_Err_Ok;
InvalidTable:
error = FT_THROW( Invalid_Table );
NoSVG:
FT_FRAME_RELEASE( table );
FT_FREE( svg );
face->svg = NULL;
return error;
}
FT_LOCAL_DEF( void )
tt_face_free_svg( TT_Face face )
{
FT_Memory memory = face->root.memory;
FT_Stream stream = face->root.stream;
Svg* svg = (Svg*)face->svg;
if ( svg )
{
FT_FRAME_RELEASE( svg->table );
FT_FREE( svg );
}
}
typedef struct Svg_doc_
{
FT_UShort start_glyph_id;
FT_UShort end_glyph_id;
FT_ULong offset;
FT_ULong length;
} Svg_doc;
static Svg_doc
extract_svg_doc( FT_Byte* stream )
{
Svg_doc doc;
doc.start_glyph_id = FT_NEXT_USHORT( stream );
doc.end_glyph_id = FT_NEXT_USHORT( stream );
doc.offset = FT_NEXT_ULONG( stream );
doc.length = FT_NEXT_ULONG( stream );
return doc;
}
static FT_Int
compare_svg_doc( Svg_doc doc,
FT_UInt glyph_index )
{
if ( glyph_index < doc.start_glyph_id )
return -1;
else if ( glyph_index > doc.end_glyph_id )
return 1;
else
return 0;
}
static FT_Error
find_doc( FT_Byte* stream,
FT_UShort num_entries,
FT_UInt glyph_index,
FT_ULong *doc_offset,
FT_ULong *doc_length,
FT_UShort *start_glyph,
FT_UShort *end_glyph )
{
FT_Error error;
Svg_doc start_doc;
Svg_doc mid_doc;
Svg_doc end_doc;
FT_Bool found = FALSE;
FT_UInt i = 0;
FT_UInt start_index = 0;
FT_UInt end_index = num_entries - 1;
FT_Int comp_res;
/* search algorithm */
if ( num_entries == 0 )
{
error = FT_THROW( Invalid_Table );
return error;
}
start_doc = extract_svg_doc( stream + start_index * 12 );
end_doc = extract_svg_doc( stream + end_index * 12 );
if ( ( compare_svg_doc( start_doc, glyph_index ) == -1 ) ||
( compare_svg_doc( end_doc, glyph_index ) == 1 ) )
{
error = FT_THROW( Invalid_Glyph_Index );
return error;
}
while ( start_index <= end_index )
{
i = ( start_index + end_index ) / 2;
mid_doc = extract_svg_doc( stream + i * 12 );
comp_res = compare_svg_doc( mid_doc, glyph_index );
if ( comp_res == 1 )
{
start_index = i + 1;
start_doc = extract_svg_doc( stream + start_index * 4 );
}
else if ( comp_res == -1 )
{
end_index = i - 1;
end_doc = extract_svg_doc( stream + end_index * 4 );
}
else
{
found = TRUE;
break;
}
}
/* search algorithm end */
if ( found != TRUE )
{
FT_TRACE5(( "SVG glyph not found\n" ));
error = FT_THROW( Invalid_Glyph_Index );
}
else
{
*doc_offset = mid_doc.offset;
*doc_length = mid_doc.length;
*start_glyph = mid_doc.start_glyph_id;
*end_glyph = mid_doc.end_glyph_id;
error = FT_Err_Ok;
}
return error;
}
FT_LOCAL_DEF( FT_Error )
tt_face_load_svg_doc( FT_GlyphSlot glyph,
FT_UInt glyph_index )
{
FT_Byte* doc_list; /* pointer to the SVG doc list */
FT_UShort num_entries; /* total number of entries in doc list */
FT_ULong doc_offset;
FT_ULong doc_length;
FT_UShort start_glyph_id;
FT_UShort end_glyph_id;
FT_Error error = FT_Err_Ok;
TT_Face face = (TT_Face)glyph->face;
FT_Memory memory = face->root.memory;
Svg* svg = (Svg*)face->svg;
FT_SVG_Document svg_document = (FT_SVG_Document)glyph->other;
FT_ASSERT( !( svg == NULL ) );
doc_list = svg->svg_doc_list;
num_entries = FT_NEXT_USHORT( doc_list );
error = find_doc( doc_list, num_entries, glyph_index,
&doc_offset, &doc_length,
&start_glyph_id, &end_glyph_id );
if ( error != FT_Err_Ok )
goto Exit;
doc_list = svg->svg_doc_list; /* reset, so we can use it again */
doc_list = (FT_Byte*)( doc_list + doc_offset );
if ( ( doc_list[0] == 0x1F ) && ( doc_list[1] == 0x8B )
&& ( doc_list[2] == 0x08 ) )
{
#ifdef FT_CONFIG_OPTION_USE_ZLIB
FT_ULong uncomp_size;
FT_Byte* uncomp_buffer;
/*
* Get the size of the original document. This helps in allotting the
* buffer to accommodate the uncompressed version. The last 4 bytes
* of the compressed document are equal to the original size modulo
* 2^32. Since the size of SVG documents is less than 2^32 bytes we
* can use this accurately. The four bytes are stored in
* little-endian format.
*/
FT_TRACE4(( "SVG document is GZIP compressed\n" ));
uncomp_size = (FT_ULong)doc_list[doc_length - 1] << 24 |
(FT_ULong)doc_list[doc_length - 2] << 16 |
(FT_ULong)doc_list[doc_length - 3] << 8 |
(FT_ULong)doc_list[doc_length - 4];
if ( FT_QALLOC( uncomp_buffer, uncomp_size ) )
goto Exit;
error = FT_Gzip_Uncompress( memory,
uncomp_buffer,
&uncomp_size,
doc_list,
doc_length );
if ( error )
{
FT_FREE( uncomp_buffer );
error = FT_THROW( Invalid_Table );
goto Exit;
}
glyph->internal->flags |= FT_GLYPH_OWN_GZIP_SVG;
doc_list = uncomp_buffer;
doc_length = uncomp_size;
#else /* !FT_CONFIG_OPTION_USE_ZLIB */
error = FT_THROW( Unimplemented_Feature );
goto Exit;
#endif /* !FT_CONFIG_OPTION_USE_ZLIB */
}
svg_document->svg_document = doc_list;
svg_document->svg_document_length = doc_length;
svg_document->metrics = glyph->face->size->metrics;
svg_document->units_per_EM = glyph->face->units_per_EM;
svg_document->start_glyph_id = start_glyph_id;
svg_document->end_glyph_id = end_glyph_id;
svg_document->transform.xx = 0x10000;
svg_document->transform.xy = 0;
svg_document->transform.yx = 0;
svg_document->transform.yy = 0x10000;
svg_document->delta.x = 0;
svg_document->delta.y = 0;
FT_TRACE5(( "start_glyph_id: %d\n", start_glyph_id ));
FT_TRACE5(( "end_glyph_id: %d\n", end_glyph_id ));
FT_TRACE5(( "svg_document:\n" ));
FT_TRACE5(( " %.*s\n", (FT_UInt)doc_length, doc_list ));
glyph->other = svg_document;
Exit:
return error;
}
#else /* !FT_CONFIG_OPTION_SVG */
/* ANSI C doesn't like empty source files */
typedef int _tt_svg_dummy;
#endif /* !FT_CONFIG_OPTION_SVG */
/* END */