339 lines
11 KiB
C++
339 lines
11 KiB
C++
/*
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* Copyright © 2016 Igalia S.L.
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*
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* This is part of HarfBuzz, a text shaping library.
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*
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* Permission is hereby granted, without written agreement and without
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* license or royalty fees, to use, copy, modify, and distribute this
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* software and its documentation for any purpose, provided that the
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* above copyright notice and the following two paragraphs appear in
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* all copies of this software.
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*
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* IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
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* DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
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* ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
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* IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
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* DAMAGE.
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*
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* THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
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* BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
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* FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS
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* ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
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* PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
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*
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* Igalia Author(s): Frédéric Wang
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*/
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#include "hb.hh"
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#ifndef HB_NO_MATH
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#include "hb-ot-math-table.hh"
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/**
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* SECTION:hb-ot-math
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* @title: hb-ot-math
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* @short_description: OpenType Math information
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* @include: hb-ot.h
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*
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* Functions for fetching mathematics layout data from OpenType fonts.
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*
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* HarfBuzz itself does not implement a math layout solution. The
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* functions and types provided can be used by client programs to access
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* the font data necessary for typesetting OpenType Math layout.
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*
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**/
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/*
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* OT::MATH
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*/
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/**
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* hb_ot_math_has_data:
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* @face: #hb_face_t to test
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*
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* Tests whether a face has a `MATH` table.
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*
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* Return value: `true` if the table is found, `false` otherwise
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*
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* Since: 1.3.3
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**/
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hb_bool_t
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hb_ot_math_has_data (hb_face_t *face)
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{
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return face->table.MATH->has_data ();
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}
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/**
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* hb_ot_math_get_constant:
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* @font: #hb_font_t to work upon
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* @constant: #hb_ot_math_constant_t the constant to retrieve
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*
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* Fetches the specified math constant. For most constants, the value returned
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* is an #hb_position_t.
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*
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* However, if the requested constant is #HB_OT_MATH_CONSTANT_SCRIPT_PERCENT_SCALE_DOWN,
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* #HB_OT_MATH_CONSTANT_SCRIPT_SCRIPT_PERCENT_SCALE_DOWN or
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* #HB_OT_MATH_CONSTANT_SCRIPT_PERCENT_SCALE_DOWN, then the return value is
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* an integer between 0 and 100 representing that percentage.
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*
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* Return value: the requested constant or zero
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*
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* Since: 1.3.3
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**/
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hb_position_t
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hb_ot_math_get_constant (hb_font_t *font,
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hb_ot_math_constant_t constant)
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{
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return font->face->table.MATH->get_constant(constant, font);
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}
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/**
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* hb_ot_math_get_glyph_italics_correction:
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* @font: #hb_font_t to work upon
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* @glyph: The glyph index from which to retrieve the value
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*
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* Fetches an italics-correction value (if one exists) for the specified
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* glyph index.
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*
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* Return value: the italics correction of the glyph or zero
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*
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* Since: 1.3.3
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**/
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hb_position_t
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hb_ot_math_get_glyph_italics_correction (hb_font_t *font,
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hb_codepoint_t glyph)
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{
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return font->face->table.MATH->get_glyph_info().get_italics_correction (glyph, font);
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}
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/**
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* hb_ot_math_get_glyph_top_accent_attachment:
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* @font: #hb_font_t to work upon
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* @glyph: The glyph index from which to retrieve the value
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*
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* Fetches a top-accent-attachment value (if one exists) for the specified
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* glyph index.
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*
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* For any glyph that does not have a top-accent-attachment value - that is,
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* a glyph not covered by the `MathTopAccentAttachment` table (or, when
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* @font has no `MathTopAccentAttachment` table or no `MATH` table, any
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* glyph) - the function synthesizes a value, returning the position at
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* one-half the glyph's advance width.
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*
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* Return value: the top accent attachment of the glyph or 0.5 * the advance
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* width of @glyph
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*
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* Since: 1.3.3
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**/
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hb_position_t
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hb_ot_math_get_glyph_top_accent_attachment (hb_font_t *font,
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hb_codepoint_t glyph)
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{
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return font->face->table.MATH->get_glyph_info().get_top_accent_attachment (glyph, font);
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}
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/**
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* hb_ot_math_is_glyph_extended_shape:
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* @face: #hb_face_t to work upon
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* @glyph: The glyph index to test
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*
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* Tests whether the given glyph index is an extended shape in the face.
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*
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* Return value: `true` if the glyph is an extended shape, `false` otherwise
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*
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* Since: 1.3.3
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**/
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hb_bool_t
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hb_ot_math_is_glyph_extended_shape (hb_face_t *face,
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hb_codepoint_t glyph)
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{
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return face->table.MATH->get_glyph_info().is_extended_shape (glyph);
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}
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/**
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* hb_ot_math_get_glyph_kerning:
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* @font: #hb_font_t to work upon
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* @glyph: The glyph index from which to retrieve the value
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* @kern: The #hb_ot_math_kern_t from which to retrieve the value
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* @correction_height: the correction height to use to determine the kerning.
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*
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* Fetches the math kerning (cut-ins) value for the specified font, glyph index, and
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* @kern.
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*
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* If the MathKern table is found, the function examines it to find a height
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* value that is greater or equal to @correction_height. If such a height
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* value is found, corresponding kerning value from the table is returned. If
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* no such height value is found, the last kerning value is returned.
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*
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* Return value: requested kerning value or zero
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*
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* Since: 1.3.3
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**/
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hb_position_t
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hb_ot_math_get_glyph_kerning (hb_font_t *font,
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hb_codepoint_t glyph,
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hb_ot_math_kern_t kern,
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hb_position_t correction_height)
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{
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return font->face->table.MATH->get_glyph_info().get_kerning (glyph,
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kern,
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correction_height,
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font);
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}
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/**
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* hb_ot_math_get_glyph_kernings:
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* @font: #hb_font_t to work upon
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* @glyph: The glyph index from which to retrieve the kernings
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* @kern: The #hb_ot_math_kern_t from which to retrieve the kernings
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* @start_offset: offset of the first kern entry to retrieve
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* @entries_count: (inout) (optional): Input = the maximum number of kern entries to return;
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* Output = the actual number of kern entries returned
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* @kern_entries: (out caller-allocates) (array length=entries_count): array of kern entries returned
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*
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* Fetches the raw MathKern (cut-in) data for the specified font, glyph index,
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* and @kern. The corresponding list of kern values and correction heights is
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* returned as a list of #hb_ot_math_kern_entry_t structs.
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*
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* See also #hb_ot_math_get_glyph_kerning, which handles selecting the
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* appropriate kern value for a given correction height.
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*
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* <note>For a glyph with @n defined kern values (where @n > 0), there are only
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* @n−1 defined correction heights, as each correction height defines a boundary
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* past which the next kern value should be selected. Therefore, only the
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* #hb_ot_math_kern_entry_t.kern_value of the uppermost #hb_ot_math_kern_entry_t
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* actually comes from the font; its corresponding
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* #hb_ot_math_kern_entry_t.max_correction_height is always set to
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* <code>INT32_MAX</code>.</note>
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*
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* Return value: the total number of kern values available or zero
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*
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* Since: 3.4.0
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**/
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unsigned int
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hb_ot_math_get_glyph_kernings (hb_font_t *font,
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hb_codepoint_t glyph,
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hb_ot_math_kern_t kern,
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unsigned int start_offset,
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unsigned int *entries_count, /* IN/OUT */
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hb_ot_math_kern_entry_t *kern_entries /* OUT */)
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{
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return font->face->table.MATH->get_glyph_info().get_kernings (glyph,
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kern,
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start_offset,
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entries_count,
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kern_entries,
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font);
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}
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/**
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* hb_ot_math_get_glyph_variants:
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* @font: #hb_font_t to work upon
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* @glyph: The index of the glyph to stretch
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* @direction: The direction of the stretching (horizontal or vertical)
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* @start_offset: offset of the first variant to retrieve
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* @variants_count: (inout): Input = the maximum number of variants to return;
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* Output = the actual number of variants returned
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* @variants: (out) (array length=variants_count): array of variants returned
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*
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* Fetches the MathGlyphConstruction for the specified font, glyph index, and
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* direction. The corresponding list of size variants is returned as a list of
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* #hb_ot_math_glyph_variant_t structs.
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*
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* <note>The @direction parameter is only used to select between horizontal
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* or vertical directions for the construction. Even though all #hb_direction_t
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* values are accepted, only the result of #HB_DIRECTION_IS_HORIZONTAL is
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* considered.</note>
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*
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* Return value: the total number of size variants available or zero
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*
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* Since: 1.3.3
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**/
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unsigned int
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hb_ot_math_get_glyph_variants (hb_font_t *font,
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hb_codepoint_t glyph,
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hb_direction_t direction,
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unsigned int start_offset,
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unsigned int *variants_count, /* IN/OUT */
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hb_ot_math_glyph_variant_t *variants /* OUT */)
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{
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return font->face->table.MATH->get_variants().get_glyph_variants (glyph, direction, font,
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start_offset,
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variants_count,
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variants);
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}
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/**
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* hb_ot_math_get_min_connector_overlap:
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* @font: #hb_font_t to work upon
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* @direction: direction of the stretching (horizontal or vertical)
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*
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* Fetches the MathVariants table for the specified font and returns the
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* minimum overlap of connecting glyphs that are required to draw a glyph
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* assembly in the specified direction.
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*
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* <note>The @direction parameter is only used to select between horizontal
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* or vertical directions for the construction. Even though all #hb_direction_t
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* values are accepted, only the result of #HB_DIRECTION_IS_HORIZONTAL is
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* considered.</note>
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*
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* Return value: requested minimum connector overlap or zero
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*
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* Since: 1.3.3
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**/
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hb_position_t
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hb_ot_math_get_min_connector_overlap (hb_font_t *font,
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hb_direction_t direction)
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{
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return font->face->table.MATH->get_variants().get_min_connector_overlap (direction, font);
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}
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/**
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* hb_ot_math_get_glyph_assembly:
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* @font: #hb_font_t to work upon
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* @glyph: The index of the glyph to stretch
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* @direction: direction of the stretching (horizontal or vertical)
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* @start_offset: offset of the first glyph part to retrieve
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* @parts_count: (inout): Input = maximum number of glyph parts to return;
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* Output = actual number of parts returned
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* @parts: (out) (array length=parts_count): the glyph parts returned
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* @italics_correction: (out): italics correction of the glyph assembly
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*
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* Fetches the GlyphAssembly for the specified font, glyph index, and direction.
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* Returned are a list of #hb_ot_math_glyph_part_t glyph parts that can be
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* used to draw the glyph and an italics-correction value (if one is defined
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* in the font).
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*
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* <note>The @direction parameter is only used to select between horizontal
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* or vertical directions for the construction. Even though all #hb_direction_t
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* values are accepted, only the result of #HB_DIRECTION_IS_HORIZONTAL is
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* considered.</note>
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*
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* Return value: the total number of parts in the glyph assembly
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*
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* Since: 1.3.3
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**/
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unsigned int
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hb_ot_math_get_glyph_assembly (hb_font_t *font,
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hb_codepoint_t glyph,
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hb_direction_t direction,
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unsigned int start_offset,
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unsigned int *parts_count, /* IN/OUT */
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hb_ot_math_glyph_part_t *parts, /* OUT */
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hb_position_t *italics_correction /* OUT */)
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{
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return font->face->table.MATH->get_variants().get_glyph_parts (glyph,
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direction,
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font,
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start_offset,
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parts_count,
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parts,
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italics_correction);
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}
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#endif
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