Add `FT_Glyph` support for OT-SVG glyphs.

* include/freetype/ftglyph.h (FT_SvgGlyphRec, FT_SvgGlyph): New structure.

* src/base/ftglyph.c: Include `otsvg.h`.
(ft_svg_glyph_init, ft_svg_glyph_done, ft_svg_glyph_copy,
ft_svg_glyph_transform, ft_svg_glyph_prepare): New function.
(ft_svg_glyph_class): New class.
(FT_New_Glyph, FT_Glyph_To_Bitmap): Updated to handle OT-SVG glyphs.
* src/base/ftglyph.h: Updated.

1 files changed, 88 insertions, 2 deletions

diff --git a/include/freetype/ftglyph.h b/include/freetype/ftglyph.h
index c934fd55c..b6071369b 100644
--- a/include/freetype/ftglyph.h
+++ b/include/freetype/ftglyph.h
@@ -126,7 +126,7 @@ FT_BEGIN_HEADER
    *
    * @description:
    *   A handle to an object used to model a bitmap glyph image.  This is a
-   *   sub-class of @FT_Glyph, and a pointer to @FT_BitmapGlyphRec.
+   *   'sub-class' of @FT_Glyph, and a pointer to @FT_BitmapGlyphRec.
    */
   typedef struct FT_BitmapGlyphRec_*  FT_BitmapGlyph;
 
@@ -142,7 +142,7 @@ FT_BEGIN_HEADER
    *
    * @fields:
    *   root ::
-   *     The root @FT_Glyph fields.
+   *     The root fields of @FT_Glyph.
    *
    *   left ::
    *     The left-side bearing, i.e., the horizontal distance from the
@@ -224,6 +224,92 @@ FT_BEGIN_HEADER
 
   /**************************************************************************
    *
+   * @type:
+   *   FT_SvgGlyph
+   *
+   * @description:
+   *   A handle to an object used to model an SVG glyph.  This is a
+   *   'sub-class' of @FT_Glyph, and a pointer to @FT_SvgGlyphRec.
+   *
+   * @since:
+   *   2.12
+   */
+  typedef struct FT_SvgGlyphRec_*  FT_SvgGlyph;
+
+
+  /**************************************************************************
+   *
+   * @struct:
+   *   FT_SvgGlyphRec
+   *
+   * @description:
+   *   A structure used for OT-SVG glyphs.  This is a 'sub-class' of
+   *   @FT_GlyphRec.
+   *
+   * @fields:
+   *   root ::
+   *     The root @FT_GlyphRec fields.
+   *
+   *   svg_document ::
+   *     A pointer to the SVG document.
+   *
+   *   svg_document_length ::
+   *     The length of `svg_document`.
+   *
+   *   glyph_index ::
+   *     The index of the glyph to be rendered.
+   *
+   *   metrics ::
+   *     A metrics object storing the size information.
+   *
+   *   units_per_EM ::
+   *     The size of the EM square.
+   *
+   *   start_glyph_id ::
+   *     The first glyph ID in the glyph range covered by this document.
+   *
+   *   end_glyph_id ::
+   *     The last glyph ID in the glyph range covered by this document.
+   *
+   *   transform ::
+   *     A 2x2 transformation matrix to apply to the glyph while rendering
+   *     it.
+   *
+   *   delta ::
+   *     Translation to apply to the glyph while rendering.
+   *
+   * @note:
+   *   The Glyph Management API requires @FT_Glyph or its 'sub-class' to have
+   *   all the information needed to completely define the glyph's rendering.
+   *   Outline-based glyphs can directly apply transformations to the outline
+   *   but this is not possible for an SVG document that hasn't been parsed.
+   *   Therefore, the transformation is stored along with the document.  In
+   *   the absence of a 'ViewBox' or 'Width'/'Height' attribute, the size of
+   *   the ViewPort should be assumed to be 'units_per_EM'.
+   */
+  typedef struct  FT_SvgGlyphRec_
+  {
+    FT_GlyphRec  root;
+
+    FT_Byte*  svg_document;
+    FT_ULong  svg_document_length;
+
+    FT_UInt  glyph_index;
+
+    FT_Size_Metrics  metrics;
+    FT_UShort        units_per_EM;
+
+    FT_UShort  start_glyph_id;
+    FT_UShort  end_glyph_id;
+
+    FT_Matrix  transform;
+    FT_Vector  delta;
+
+  } FT_SvgGlyphRec;
+
+
+  /**************************************************************************
+   *
    * @function:
    *   FT_New_Glyph
    *