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/****************************************************************************
*
* ttsvg.c
*
* OpenType SVG Color (specification).
*
* Copyright (C) 2018-2019 by
* David Turner, Robert Wilhelm, and Werner Lemberg.
*
* 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 FT_INTERNAL_STREAM_H
#include FT_INTERNAL_OBJECTS_H
#include FT_TRUETYPE_TAGS_H
#include FT_GZIP_H
#include FT_SVG_RENDERER_H
#include "ttsvg.h"
/* TODO: (OT-SVG) Decide whether to add documentation here or not */
typedef struct Svg_
{
FT_UShort version; /* Table version (starting at 0) */
FT_UShort num_entries; /* Number of SVG document records */
/* Pointer to the starting of SVG Document List */
FT_Byte* svg_doc_list;
/* Memory that backs up SVG */
void* table;
FT_ULong table_size;
} Svg;
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( FT_FRAME_EXTRACT( table_size, table ))
goto NoSVG;
/* Allocate the 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 == 0 )
goto InvalidTable;
svg->svg_doc_list = (FT_Byte*)( table + offsetToSVGDocumentList );
p = svg->svg_doc_list;
svg->num_entries = FT_NEXT_USHORT( p );
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 );
}
}
FT_Error
find_doc( FT_Byte* stream,
FT_UShort num_entries,
FT_UInt glyph_index,
FT_ULong *doc_offset,
FT_ULong *doc_length )
{
FT_Error error;
FT_UShort start_glyph_id;
FT_UShort end_glyph_id;
FT_ULong cur_doc_offset;
FT_ULong cur_doc_length;
FT_Bool found = FALSE;
FT_UInt i = 0;
/* TODO: (OT-SVG) Convert to efficient search algorithm */
/* TODO: (OT-SVG) Use Frame Fields here instead of `FT_NEXT_*' */
for ( i = 0; i < num_entries; i++)
{
start_glyph_id = FT_NEXT_USHORT( stream );
end_glyph_id = FT_NEXT_USHORT( stream );
cur_doc_offset = FT_NEXT_ULONG( stream );
cur_doc_length = FT_NEXT_ULONG( stream );
if ( ( glyph_index >= start_glyph_id) &&
( glyph_index <= end_glyph_id ) )
{
found = TRUE;
*doc_offset = cur_doc_offset;
*doc_length = cur_doc_length;
break;
}
}
if ( found != TRUE )
error = FT_THROW( Invalid_Glyph_Index );
else
error = FT_Err_Ok;
return error;
}
FT_LOCAL_DEF(FT_Error)
tt_face_load_svg_doc( FT_GlyphSlot glyph,
FT_UInt glyph_index )
{
/* TODO: (OT-SVG) properly clean stuff here on errors */
FT_Byte* doc_list; /* Pointer to the Svg Document List */
FT_UShort num_entries; /* Total no of entires in doc list */
FT_ULong doc_offset;
FT_ULong doc_length;
FT_ULong uncomp_size;
FT_Byte* uncomp_buffer;
FT_Bool is_gzip_encoded = FALSE;
FT_Error error = FT_Err_Ok;
TT_Face face = (TT_Face)glyph->face;
FT_Memory memory = face->root.memory;
Svg* svg = face->svg;
FT_SVG_Document svg_document = glyph->other;
/* handle svg being 0x0 situation here */
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 );
if ( error != FT_Err_Ok )
return error;
doc_list = svg->svg_doc_list; /* Reset to 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 ) )
{
is_gzip_encoded = TRUE;
/* get the size of the orignal document. This helps in alotting the
* buffer to accomodate the uncompressed version. The last 4 bytes
* of the compressed document are equal to orignal_size modulo 2^32.
* Since SVG docs will be lesser in size then 2^32, we can use this
* accurately. The four bytes are stored in little-endian format.
*/
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];
uncomp_buffer = (FT_Byte*) memory->alloc(memory, uncomp_size);
glyph->internal->flags |= FT_GLYPH_OWN_GZIP_SVG;
error = FT_Gzip_Uncompress( memory, uncomp_buffer, &uncomp_size,
doc_list, doc_length );
if ( error != FT_Err_Ok )
{
error = FT_THROW( Invalid_Table );
return error;
}
doc_list = uncomp_buffer;
doc_length = uncomp_size;
}
svg_document->svg_document = doc_list;
svg_document->svg_document_length = doc_length;
svg_document->metrics = glyph->face->size->metrics;
glyph->other = svg_document;
glyph->metrics.horiAdvance *= ((float)glyph->face->size->metrics.x_ppem)/((float)glyph->face->units_per_EM) * 64.0;
glyph->metrics.vertAdvance *= ((float)glyph->face->size->metrics.y_ppem)/((float)glyph->face->units_per_EM) * 64.0;
return FT_Err_Ok;
}
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