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Add a `units_per_EM' field. 

A field `units_per_EM' is added to `FT_SVG_DocumentRec' and
`FT_SvgGlyphRec'. This is needed because the renderer needs this
info to properly scale the SVGs if the viewbox width and height
differ from `face->units_per_EM'. Face object can't be accessed
because of the restrictions put by `FT_Glyph_To_Bitmap' thus this
has to be provided separately just like `metrics'.
This commit is contained in:
Moazin Khatti 2019-06-24 00:33:45 +05:00
parent 7275d6562f
commit e48cf716f8
4 changed files with 34 additions and 0 deletions
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15
include/freetype/ftglyph.h
View File

@ -259,6 +259,20 @@ FT_BEGIN_HEADER
*
* metrics ::
* A metrics object storing the size information.
*
* units_per_EM ::
* The size of the EM square.
*
* @note:
* `metrics' and `units_per_EM' might look like repetitions since both
* fields are stored in face objects. However, the Glyph Management API
* requires an `FT_Glyph' to store all the information that completely
* describes a glyph. Outline glyphs are themselves scaled thus they
* don't need this information. However, SVG documents do. The field of
* `units_per_EM' is needed because the SVG is to be scaled in case its
* viewbox size differs from `units_per_EM'. For more info, refer to
* the section `Coordinate Systems and Glyph Metrics' of the OpenType
* SVG specs.
*/
typedef struct FT_SvgGlyphRec_
{
@ -267,6 +281,7 @@ FT_BEGIN_HEADER
FT_ULong svg_document_length;
FT_UInt glyph_index;
FT_Size_Metrics metrics;
FT_UShort units_per_EM;
/* TODO: (OT-SVG) Maybe put a transformation matrix here */
} FT_SvgGlyphRec;

15
include/freetype/svgrenderer.h
View File

@ -165,6 +165,20 @@ FT_BEGIN_HEADER
*
* metrics ::
* A metrics object storing the size information.
*
* units_per_EM ::
* The size of the EM square.
*
* @note:
* `metrics' and `units_per_EM' might look like repetitions since both
* fields are stored in face objects. However, the Glyph Management API
* requires an `FT_Glyph' to store all the information that completely
* describes a glyph. Outline glyphs are themselves scaled thus they
* don't need this information. However, SVG documents do. The field of
* `units_per_EM' is needed because the SVG is to be scaled in case its
* viewbox size differs from `units_per_EM'. For more info, refer to
* the section `Coordinate Systems and Glyph Metrics' of the OpenType
* SVG specs.
*/
typedef struct FT_SVG_DocumentRec_
@ -172,6 +186,7 @@ FT_BEGIN_HEADER
FT_Byte* svg_document;
FT_ULong svg_document_length;
FT_Size_Metrics metrics;
FT_UShort units_per_EM;
} FT_SVG_DocumentRec;
/**************************************************************************

3
src/base/ftglyph.c
View File

@ -327,6 +327,7 @@
glyph->svg_document_length = doc_length;
glyph->glyph_index = slot->glyph_index;
glyph->metrics = document->metrics;
glyph->units_per_EM = document->units_per_EM;
/* copy the document into glyph */
FT_MEM_COPY( glyph->svg_document, document->svg_document, doc_length );
@ -376,6 +377,7 @@
target->glyph_index = source->glyph_index;
target->svg_document_length = source->svg_document_length;
target->metrics = source->metrics;
target->units_per_EM = source->units_per_EM;
/* allocate space for the svg document */
target->svg_document = memory->alloc( memory,
@ -410,6 +412,7 @@
document->svg_document = glyph->svg_document;
document->svg_document_length = glyph->svg_document_length;
document->metrics = glyph->metrics;
document->units_per_EM = glyph->units_per_EM;
slot->format = FT_GLYPH_FORMAT_SVG;
slot->other = document;

1
src/sfnt/ttsvg.c
View File

@ -232,6 +232,7 @@
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;
glyph->other = svg_document;
glyph->metrics.horiAdvance *= ((float)glyph->face->size->metrics.x_ppem)/((float)glyph->face->units_per_EM) * 64.0;