freetype-commit
[Top][All Lists]
Advanced
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

[Git][freetype/freetype][master] More documentation on handling OT-SVG.

From: Werner Lemberg (@wl)
Subject: [Git][freetype/freetype][master] More documentation on handling OT-SVG.
Date: Sun, 23 Jan 2022 11:24:36 +0000

Werner Lemberg pushed to branch master at FreeType / FreeType

Commits:

4 changed files:

Changes:

  • docs/CHANGES
    1 
    +CHANGES BETWEEN 2.11.1 and 2.12.0
    2 
    +
    3 
    +  I. IMPORTANT CHANGES
    4 
    +
    5 
    +  - FreeType  now   handles  OT-SVG  fonts,  to   be  controlled  with
    6 
    +    `FT_CONFIG_OPTION_SVG`  configuration macro.   By default,  it can
    7 
    +    only load the 'SVG ' table of an OpenType font.  However, by using
    8 
    +    the `svg-hooks` property of the new 'ot-svg' module it is possible
    9 
    +    to register an  external SVG rendering engine.   The FreeType demo
    10 
    +    programs  have been  set  up  to use  'librsvg'  as the  rendering
    11 
    +    library.
    12 
    +
    13 
    +    This work was Moazin Kathri's GSoC 2019 project.
    14 
    +
    15 
    +
    16 
    +======================================================================
    17 
    +
    1 18 
     CHANGES BETWEEN 2.11.0 and 2.11.1
    2 19
    3 20 
       I. IMPORTANT CHANGES

  • include/freetype/ftchapters.h
    ... ... @@ -62,6 +62,7 @@
    62 62 
        *   cid_fonts
    63 63 
        *   pfr_fonts
    64 64 
        *   winfnt_fonts
    65 
    +   *   svg_fonts
    65 66 
        *   font_formats
    66 67 
        *   gasp_table
    67 68 
        *
    ... ... @@ -82,6 +83,7 @@
    82 83 
        *   t1_cid_driver
    83 84 
        *   tt_driver
    84 85 
        *   pcf_driver
    86 
    +   *   ot_svg_driver
    85 87 
        *   properties
    86 88 
        *   parameter_tags
    87 89 
        *   lcd_rendering

  • include/freetype/ftdriver.h
    ... ... @@ -212,16 +212,14 @@ FT_BEGIN_HEADER
    212 212 
        * @description:
    213 213 
        *   While FreeType's TrueType driver doesn't expose API functions by
    214 214 
        *   itself, it is possible to control its behaviour with @FT_Property_Set
    215 
    -   *   and @FT_Property_Get.  The following lists the available properties
    216 
    -   *   together with the necessary macros and structures.
    217 
    -   *
    218 
    -   *   The TrueType driver's module name is 'truetype'.
    215 
    +   *   and @FT_Property_Get.
    219 216 
        *
    220 
    -   *   A single property @interpreter-version is available, as documented in
    221 
    -   *   the @properties section.
    217 
    +   *   The TrueType driver's module name is 'truetype'; a single property
    218 
    +   *   @interpreter-version is available, as documented in the @properties
    219 
    +   *   section.
    222 220 
        *
    223 
    -   *   We start with a list of definitions, kindly provided by Greg
    224 
    -   *   Hitchcock.
    221 
    +   *   To help understand the differences between interpreter versions, we
    222 
    +   *   introduce a list of definitions, kindly provided by Greg Hitchcock.
    225 223 
        *
    226 224 
        *   _Bi-Level Rendering_
    227 225 
        *
    ... ... @@ -300,6 +298,31 @@ FT_BEGIN_HEADER
    300 298 
        */
    301 299
    302 300
    301 
    +  /**************************************************************************
    302 
    +   *
    303 
    +   * @section:
    304 
    +   *   ot_svg_driver
    305 
    +   *
    306 
    +   * @title:
    307 
    +   *   The SVG driver
    308 
    +   *
    309 
    +   * @abstract:
    310 
    +   *   Controlling the external rendering of OT-SVG glyphs.
    311 
    +   *
    312 
    +   * @description:
    313 
    +   *   By default, FreeType can only load the 'SVG~' table of OpenType fonts
    314 
    +   *   if configuration macro `FT_CONFIG_OPTION_SVG` is defined.  To make it
    315 
    +   *   render SVG glyphs, an external SVG rendering library is needed.  All
    316 
    +   *   details on the interface between FreeType and the external library
    317 
    +   *   via function hooks can be found in section @svg_fonts.
    318 
    +   *
    319 
    +   *   The OT-SVG driver's module name is 'ot-svg'; it supports a single
    320 
    +   *   property called @svg-hooks, documented below in the @properties
    321 
    +   *   section.
    322 
    +   *
    323 
    +   */
    324 
    +
    325 
    +
    303 326 
       /**************************************************************************
    304 327 
        *
    305 328 
        * @section:
    ... ... @@ -798,6 +821,40 @@ FT_BEGIN_HEADER
    798 821 
        */
    799 822
    800 823
    824 
    +  /**************************************************************************
    825 
    +   *
    826 
    +   * @property:
    827 
    +   *   svg-hooks
    828 
    +   *
    829 
    +   * @description:
    830 
    +   *   Set up the interface between FreeType and an extern SVG rendering
    831 
    +   *   library like 'librsvg'.  All details on the function hooks can be
    832 
    +   *   found in section @svg_fonts.
    833 
    +   *
    834 
    +   * @example:
    835 
    +   *   The following example code expects that the four hook functions
    836 
    +   *   `svg_*` are defined elsewhere.  Error handling is omitted, too.
    837 
    +   *
    838 
    +   *   ```
    839 
    +   *     FT_Library  library;
    840 
    +   *     SVG_RendererHooks  hooks = {
    841 
    +   *                          (SVG_Lib_Init_Func)svg_init,
    842 
    +   *                          (SVG_Lib_Free_Func)svg_free,
    843 
    +   *                          (SVG_Lib_Render_Func)svg_render,
    844 
    +   *                          (SVG_Lib_Preset_Slot_Func)svg_preset_slot };
    845 
    +   *
    846 
    +   *
    847 
    +   *     FT_Init_FreeType( &library );
    848 
    +   *
    849 
    +   *     FT_Property_Set( library, "ot-svg",
    850 
    +   *                               "svg-hooks", &hooks );
    851 
    +   *   ```
    852 
    +   *
    853 
    +   * @since:
    854 
    +   *   2.12
    855 
    +   */
    856 
    +
    857 
    +
    801 858 
       /**************************************************************************
    802 859 
        *
    803 860 
        * @property:

  • include/freetype/otsvg.h
    ... ... @@ -31,6 +31,29 @@
    31 31 
     FT_BEGIN_HEADER
    32 32
    33 33
    34 
    +  /**************************************************************************
    35 
    +   *
    36 
    +   * @section:
    37 
    +   *   svg_fonts
    38 
    +   *
    39 
    +   * @title:
    40 
    +   *   OpenType SVG Fonts
    41 
    +   *
    42 
    +   * @abstract:
    43 
    +   *   OT-SVG API between FreeType and an external SVG rendering library.
    44 
    +   *
    45 
    +   * @description:
    46 
    +   *   This section describes the four hooks necessary to render SVG
    47 
    +   *   'documents' that are contained in an OpenType font's 'SVG~' table.
    48 
    +   *
    49 
    +   *   For more information on the implementation, see our standard hooks
    50 
    +   *   based on 'librsvg' in the [FreeType Demo
    51 
    +   *   Programs](https://gitlab.freedesktop.org/freetype/freetype-demos)
    52 
    +   *   repository.
    53 
    +   *
    54 
    +   */
    55 
    +
    56 
    +
    34 57 
       /**************************************************************************
    35 58 
        *
    36 59 
        * @functype:
    ... ... @@ -42,9 +65,6 @@ FT_BEGIN_HEADER
    42 65 
        *   one would want to allocate a structure and point the `data_pointer`
    43 66 
        *   to it and perform any library initializations that might be needed.
    44 67 
        *
    45 
    -   *   For more information on the implementation, see our standard hooks
    46 
    -   *   based on Librsvg in the 'FreeType Demo Programs' repository.
    47 
    -   *
    48 68 
        * @inout:
    49 69 
        *   data_pointer ::
    50 70 
        *     The SVG rendering module stores a pointer variable that can be used
    ... ... @@ -77,9 +97,6 @@ FT_BEGIN_HEADER
    77 97 
        *   structure that was allocated in the init hook and perform any
    78 98 
        *   library-related closure that might be needed.
    79 99 
        *
    80 
    -   *   For more information on the implementation, see our standard hooks
    81 
    -   *   based on Librsvg in the 'FreeType Demo Programs' repository.
    82 
    -   *
    83 100 
        * @inout:
    84 101 
        *   data_pointer ::
    85 102 
        *     The SVG rendering module stores a pointer variable that can be used
    ... ... @@ -101,7 +118,7 @@ FT_BEGIN_HEADER
    101 118 
        *
    102 119 
        * @description:
    103 120 
        *   A callback that is called to render an OT-SVG glyph.  This callback
    104 
    -   *   hook is called right after the preset hook @SVG_Lib_Preset_SlotFunc
    121 
    +   *   hook is called right after the preset hook @SVG_Lib_Preset_Slot_Func
    105 122 
        *   has been called with `cache` set to `TRUE`.  The data necessary to
    106 123 
        *   render is available through the handle @FT_SVG_Document, which is set
    107 124 
        *   in the `other` field of @FT_GlyphSlotRec.
    ... ... @@ -110,9 +127,6 @@ FT_BEGIN_HEADER
    110 127 
        *   buffer that is allocated already at `slot->bitmap.buffer`.  It also
    111 128 
        *   sets the `num_grays` value as well as `slot->format`.
    112 129 
        *
    113 
    -   *   For more information on the implementation, see our standard hooks
    114 
    -   *   based on Librsvg in the 'FreeType Demo Programs' repository.
    115 
    -   *
    116 130 
        * @input:
    117 131 
        *   slot ::
    118 132 
        *     The slot to render.
    ... ... @@ -145,6 +159,7 @@ FT_BEGIN_HEADER
    145 159 
        *   two places.
    146 160 
        *
    147 161 
        *   1. When `FT_Load_Glyph` needs to preset the glyph slot.
    162 
    +   *
    148 163 
        *   2. Right before the `svg` module calls the render callback hook.
    149 164 
        *
    150 165 
        *   When it is the former, the argument `cache` is set to `FALSE`.  When
    ... ... @@ -165,9 +180,6 @@ FT_BEGIN_HEADER
    165 180 
        *   matrices into the SVG coordinate system, as the original matrix is
    166 181 
        *   intended for the TTF/CFF coordinate system.
    167 182 
        *
    168 
    -   *   For more information on the implementation, see our standard hooks
    169 
    -   *   based on Librsvg in the 'FreeType Demo Programs' repository.
    170 
    -   *
    171 183 
        * @input:
    172 184 
        *   slot ::
    173 185 
        *     The glyph slot that has the SVG document loaded.
    ... ... @@ -201,8 +213,8 @@ FT_BEGIN_HEADER
    201 213 
        *
    202 214 
        * @description:
    203 215 
        *   A structure that stores the four hooks needed to render OT-SVG glyphs
    204 
    -   *   properly.  The structure is publicly used to set the hooks via driver
    205 
    -   *   properties.
    216 
    +   *   properly.  The structure is publicly used to set the hooks via the
    217 
    +   *   @svg-hooks driver property.
    206 218 
        *
    207 219 
        *   The behavior of each hook is described in its documentation.  One
    208 220 
        *   thing to note is that the preset hook and the render hook often need
    ... ... @@ -211,9 +223,6 @@ FT_BEGIN_HEADER
    211 223 
        *   For example, in the preset hook one can draw the glyph on a recorder
    212 224 
        *   surface and later create a bitmap surface from it in the render hook.
    213 225 
        *
    214 
    -   *   For more information on the implementation, see our standard hooks
    215 
    -   *   based on Librsvg in the 'FreeType Demo Programs' repository.
    216 
    -   *
    217 226 
        * @fields:
    218 227 
        *   init_svg ::
    219 228 
        *     The initialization hook.
    ... ... @@ -244,7 +253,7 @@ FT_BEGIN_HEADER
    244 253 
       /**************************************************************************
    245 254 
        *
    246 255 
        * @struct:
    247 
    -   *   FT_SVG_DocumentRec_
    256 
    +   *   FT_SVG_DocumentRec
    248 257 
        *
    249 258 
        * @description:
    250 259 
        *   A structure that models one SVG document.
    ... ... @@ -276,12 +285,12 @@ FT_BEGIN_HEADER
    276 285 
        *     The translation to apply to the glyph while rendering.
    277 286 
        *
    278 287 
        * @note:
    279 
    -   *   When the slot is passed down to a renderer, the renderer can only
    280 
    -   *   access the `metrics` and `units_per_EM` fields via `slot->face`.
    281 
    -   *   However, when `FT_Glyph_To_Bitmap` sets up a dummy object, it has no
    282 
    -   *   way to set a `face` object.  Thus, metrics information and
    283 
    -   *   `units_per_EM` (which is necessary for OT-SVG) has to be stored
    284 
    -   *   separately.
    288 
    +   *   When an @FT_GlyphSlot object `slot` is passed down to a renderer, the
    289 
    +   *   renderer can only access the `metrics` and `units_per_EM` fields via
    290 
    +   *   `slot->face`.  However, when @FT_Glyph_To_Bitmap sets up a dummy
    291 
    +   *   object, it has no way to set a `face` object.  Thus, metrics
    292 
    +   *   information and `units_per_EM` (which is necessary for OT-SVG) has to
    293 
    +   *   be stored separately.
    285 294 
        *
    286 295 
        * @since:
    287 296 
        *   2.12

    • —
    View it on GitLab.
    You're receiving this email because of your account on gitlab.freedesktop.org. If you'd like to receive fewer emails, you can adjust your notification settings.

    reply via email to
    [Prev in Thread] Current Thread [Next in Thread]