mirror of
git://git.sv.nongnu.org/freetype/freetype2.git
synced 2025-05-09 05:03:53 +00:00
More documentation on handling OT-SVG.
This commit is contained in:
Werner Lemberg
parent
9c1538525b
commit
21d0fa3742
17
docs/CHANGES
17
docs/CHANGES
@ -1,3 +1,20 @@
|
||||
CHANGES BETWEEN 2.11.1 and 2.12.0
|
||||
|
||||
I. IMPORTANT CHANGES
|
||||
|
||||
- FreeType now handles OT-SVG fonts, to be controlled with
|
||||
`FT_CONFIG_OPTION_SVG` configuration macro. By default, it can
|
||||
only load the 'SVG ' table of an OpenType font. However, by using
|
||||
the `svg-hooks` property of the new 'ot-svg' module it is possible
|
||||
to register an external SVG rendering engine. The FreeType demo
|
||||
programs have been set up to use 'librsvg' as the rendering
|
||||
library.
|
||||
|
||||
This work was Moazin Kathri's GSoC 2019 project.
|
||||
|
||||
|
||||
======================================================================
|
||||
|
||||
CHANGES BETWEEN 2.11.0 and 2.11.1
|
||||
|
||||
I. IMPORTANT CHANGES
|
||||
|
||||
@ -62,6 +62,7 @@
|
||||
* cid_fonts
|
||||
* pfr_fonts
|
||||
* winfnt_fonts
|
||||
* svg_fonts
|
||||
* font_formats
|
||||
* gasp_table
|
||||
*
|
||||
@ -82,6 +83,7 @@
|
||||
* t1_cid_driver
|
||||
* tt_driver
|
||||
* pcf_driver
|
||||
* ot_svg_driver
|
||||
* properties
|
||||
* parameter_tags
|
||||
* lcd_rendering
|
||||
|
||||
@ -212,16 +212,14 @@ FT_BEGIN_HEADER
|
||||
* @description:
|
||||
* While FreeType's TrueType driver doesn't expose API functions by
|
||||
* itself, it is possible to control its behaviour with @FT_Property_Set
|
||||
* and @FT_Property_Get. The following lists the available properties
|
||||
* together with the necessary macros and structures.
|
||||
* and @FT_Property_Get.
|
||||
*
|
||||
* The TrueType driver's module name is 'truetype'.
|
||||
* The TrueType driver's module name is 'truetype'; a single property
|
||||
* @interpreter-version is available, as documented in the @properties
|
||||
* section.
|
||||
*
|
||||
* A single property @interpreter-version is available, as documented in
|
||||
* the @properties section.
|
||||
*
|
||||
* We start with a list of definitions, kindly provided by Greg
|
||||
* Hitchcock.
|
||||
* To help understand the differences between interpreter versions, we
|
||||
* introduce a list of definitions, kindly provided by Greg Hitchcock.
|
||||
*
|
||||
* _Bi-Level Rendering_
|
||||
*
|
||||
@ -300,6 +298,31 @@ FT_BEGIN_HEADER
|
||||
*/
|
||||
|
||||
|
||||
/**************************************************************************
|
||||
*
|
||||
* @section:
|
||||
* ot_svg_driver
|
||||
*
|
||||
* @title:
|
||||
* The SVG driver
|
||||
*
|
||||
* @abstract:
|
||||
* Controlling the external rendering of OT-SVG glyphs.
|
||||
*
|
||||
* @description:
|
||||
* By default, FreeType can only load the 'SVG~' table of OpenType fonts
|
||||
* if configuration macro `FT_CONFIG_OPTION_SVG` is defined. To make it
|
||||
* render SVG glyphs, an external SVG rendering library is needed. All
|
||||
* details on the interface between FreeType and the external library
|
||||
* via function hooks can be found in section @svg_fonts.
|
||||
*
|
||||
* The OT-SVG driver's module name is 'ot-svg'; it supports a single
|
||||
* property called @svg-hooks, documented below in the @properties
|
||||
* section.
|
||||
*
|
||||
*/
|
||||
|
||||
|
||||
/**************************************************************************
|
||||
*
|
||||
* @section:
|
||||
@ -798,6 +821,40 @@ FT_BEGIN_HEADER
|
||||
*/
|
||||
|
||||
|
||||
/**************************************************************************
|
||||
*
|
||||
* @property:
|
||||
* svg-hooks
|
||||
*
|
||||
* @description:
|
||||
* Set up the interface between FreeType and an extern SVG rendering
|
||||
* library like 'librsvg'. All details on the function hooks can be
|
||||
* found in section @svg_fonts.
|
||||
*
|
||||
* @example:
|
||||
* The following example code expects that the four hook functions
|
||||
* `svg_*` are defined elsewhere. Error handling is omitted, too.
|
||||
*
|
||||
* ```
|
||||
* FT_Library library;
|
||||
* SVG_RendererHooks hooks = {
|
||||
* (SVG_Lib_Init_Func)svg_init,
|
||||
* (SVG_Lib_Free_Func)svg_free,
|
||||
* (SVG_Lib_Render_Func)svg_render,
|
||||
* (SVG_Lib_Preset_Slot_Func)svg_preset_slot };
|
||||
*
|
||||
*
|
||||
* FT_Init_FreeType( &library );
|
||||
*
|
||||
* FT_Property_Set( library, "ot-svg",
|
||||
* "svg-hooks", &hooks );
|
||||
* ```
|
||||
*
|
||||
* @since:
|
||||
* 2.12
|
||||
*/
|
||||
|
||||
|
||||
/**************************************************************************
|
||||
*
|
||||
* @property:
|
||||
|
||||
@ -31,6 +31,29 @@
|
||||
FT_BEGIN_HEADER
|
||||
|
||||
|
||||
/**************************************************************************
|
||||
*
|
||||
* @section:
|
||||
* svg_fonts
|
||||
*
|
||||
* @title:
|
||||
* OpenType SVG Fonts
|
||||
*
|
||||
* @abstract:
|
||||
* OT-SVG API between FreeType and an external SVG rendering library.
|
||||
*
|
||||
* @description:
|
||||
* This section describes the four hooks necessary to render SVG
|
||||
* 'documents' that are contained in an OpenType font's 'SVG~' table.
|
||||
*
|
||||
* For more information on the implementation, see our standard hooks
|
||||
* based on 'librsvg' in the [FreeType Demo
|
||||
* Programs](https://gitlab.freedesktop.org/freetype/freetype-demos)
|
||||
* repository.
|
||||
*
|
||||
*/
|
||||
|
||||
|
||||
/**************************************************************************
|
||||
*
|
||||
* @functype:
|
||||
@ -42,9 +65,6 @@ FT_BEGIN_HEADER
|
||||
* one would want to allocate a structure and point the `data_pointer`
|
||||
* to it and perform any library initializations that might be needed.
|
||||
*
|
||||
* For more information on the implementation, see our standard hooks
|
||||
* based on Librsvg in the 'FreeType Demo Programs' repository.
|
||||
*
|
||||
* @inout:
|
||||
* data_pointer ::
|
||||
* The SVG rendering module stores a pointer variable that can be used
|
||||
@ -77,9 +97,6 @@ FT_BEGIN_HEADER
|
||||
* structure that was allocated in the init hook and perform any
|
||||
* library-related closure that might be needed.
|
||||
*
|
||||
* For more information on the implementation, see our standard hooks
|
||||
* based on Librsvg in the 'FreeType Demo Programs' repository.
|
||||
*
|
||||
* @inout:
|
||||
* data_pointer ::
|
||||
* The SVG rendering module stores a pointer variable that can be used
|
||||
@ -101,7 +118,7 @@ FT_BEGIN_HEADER
|
||||
*
|
||||
* @description:
|
||||
* A callback that is called to render an OT-SVG glyph. This callback
|
||||
* hook is called right after the preset hook @SVG_Lib_Preset_SlotFunc
|
||||
* hook is called right after the preset hook @SVG_Lib_Preset_Slot_Func
|
||||
* has been called with `cache` set to `TRUE`. The data necessary to
|
||||
* render is available through the handle @FT_SVG_Document, which is set
|
||||
* in the `other` field of @FT_GlyphSlotRec.
|
||||
@ -110,9 +127,6 @@ FT_BEGIN_HEADER
|
||||
* buffer that is allocated already at `slot->bitmap.buffer`. It also
|
||||
* sets the `num_grays` value as well as `slot->format`.
|
||||
*
|
||||
* For more information on the implementation, see our standard hooks
|
||||
* based on Librsvg in the 'FreeType Demo Programs' repository.
|
||||
*
|
||||
* @input:
|
||||
* slot ::
|
||||
* The slot to render.
|
||||
@ -145,6 +159,7 @@ FT_BEGIN_HEADER
|
||||
* two places.
|
||||
*
|
||||
* 1. When `FT_Load_Glyph` needs to preset the glyph slot.
|
||||
*
|
||||
* 2. Right before the `svg` module calls the render callback hook.
|
||||
*
|
||||
* When it is the former, the argument `cache` is set to `FALSE`. When
|
||||
@ -165,9 +180,6 @@ FT_BEGIN_HEADER
|
||||
* matrices into the SVG coordinate system, as the original matrix is
|
||||
* intended for the TTF/CFF coordinate system.
|
||||
*
|
||||
* For more information on the implementation, see our standard hooks
|
||||
* based on Librsvg in the 'FreeType Demo Programs' repository.
|
||||
*
|
||||
* @input:
|
||||
* slot ::
|
||||
* The glyph slot that has the SVG document loaded.
|
||||
@ -201,8 +213,8 @@ FT_BEGIN_HEADER
|
||||
*
|
||||
* @description:
|
||||
* A structure that stores the four hooks needed to render OT-SVG glyphs
|
||||
* properly. The structure is publicly used to set the hooks via driver
|
||||
* properties.
|
||||
* properly. The structure is publicly used to set the hooks via the
|
||||
* @svg-hooks driver property.
|
||||
*
|
||||
* The behavior of each hook is described in its documentation. One
|
||||
* thing to note is that the preset hook and the render hook often need
|
||||
@ -211,9 +223,6 @@ FT_BEGIN_HEADER
|
||||
* For example, in the preset hook one can draw the glyph on a recorder
|
||||
* surface and later create a bitmap surface from it in the render hook.
|
||||
*
|
||||
* For more information on the implementation, see our standard hooks
|
||||
* based on Librsvg in the 'FreeType Demo Programs' repository.
|
||||
*
|
||||
* @fields:
|
||||
* init_svg ::
|
||||
* The initialization hook.
|
||||
@ -244,7 +253,7 @@ FT_BEGIN_HEADER
|
||||
/**************************************************************************
|
||||
*
|
||||
* @struct:
|
||||
* FT_SVG_DocumentRec_
|
||||
* FT_SVG_DocumentRec
|
||||
*
|
||||
* @description:
|
||||
* A structure that models one SVG document.
|
||||
@ -276,12 +285,12 @@ FT_BEGIN_HEADER
|
||||
* The translation to apply to the glyph while rendering.
|
||||
*
|
||||
* @note:
|
||||
* When the slot is passed down to a renderer, the renderer can only
|
||||
* access the `metrics` and `units_per_EM` fields via `slot->face`.
|
||||
* However, when `FT_Glyph_To_Bitmap` sets up a dummy object, it has no
|
||||
* way to set a `face` object. Thus, metrics information and
|
||||
* `units_per_EM` (which is necessary for OT-SVG) has to be stored
|
||||
* separately.
|
||||
* When an @FT_GlyphSlot object `slot` is passed down to a renderer, the
|
||||
* renderer can only access the `metrics` and `units_per_EM` fields via
|
||||
* `slot->face`. However, when @FT_Glyph_To_Bitmap sets up a dummy
|
||||
* object, it has no way to set a `face` object. Thus, metrics
|
||||
* information and `units_per_EM` (which is necessary for OT-SVG) has to
|
||||
* be stored separately.
|
||||
*
|
||||
* @since:
|
||||
* 2.12
|
||||
|
||||
Loading…
x
Reference in New Issue
Block a user