harfbuzz/src/hb-ot-math.cc

339 lines
11 KiB
C++
Raw Blame History

This file contains ambiguous Unicode characters

This file contains Unicode characters that might be confused with other characters. If you think that this is intentional, you can safely ignore this warning. Use the Escape button to reveal them.

/*
* Copyright © 2016 Igalia S.L.
*
* This is part of HarfBuzz, a text shaping library.
*
* Permission is hereby granted, without written agreement and without
* license or royalty fees, to use, copy, modify, and distribute this
* software and its documentation for any purpose, provided that the
* above copyright notice and the following two paragraphs appear in
* all copies of this software.
*
* IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
* DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
* ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
* IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
* DAMAGE.
*
* THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
* BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
* FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS
* ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
* PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
*
* Igalia Author(s): Frédéric Wang
*/
#include "hb.hh"
#ifndef HB_NO_MATH
#include "hb-ot-math-table.hh"
/**
* SECTION:hb-ot-math
* @title: hb-ot-math
* @short_description: OpenType Math information
* @include: hb-ot.h
*
* Functions for fetching mathematics layout data from OpenType fonts.
*
* HarfBuzz itself does not implement a math layout solution. The
* functions and types provided can be used by client programs to access
* the font data necessary for typesetting OpenType Math layout.
*
**/
/*
* OT::MATH
*/
/**
* hb_ot_math_has_data:
* @face: #hb_face_t to test
*
* Tests whether a face has a `MATH` table.
*
* Return value: `true` if the table is found, `false` otherwise
*
* Since: 1.3.3
**/
hb_bool_t
hb_ot_math_has_data (hb_face_t *face)
{
return face->table.MATH->has_data ();
}
/**
* hb_ot_math_get_constant:
* @font: #hb_font_t to work upon
* @constant: #hb_ot_math_constant_t the constant to retrieve
*
* Fetches the specified math constant. For most constants, the value returned
* is an #hb_position_t.
*
* However, if the requested constant is #HB_OT_MATH_CONSTANT_SCRIPT_PERCENT_SCALE_DOWN,
* #HB_OT_MATH_CONSTANT_SCRIPT_SCRIPT_PERCENT_SCALE_DOWN or
* #HB_OT_MATH_CONSTANT_SCRIPT_PERCENT_SCALE_DOWN, then the return value is
* an integer between 0 and 100 representing that percentage.
*
* Return value: the requested constant or zero
*
* Since: 1.3.3
**/
hb_position_t
hb_ot_math_get_constant (hb_font_t *font,
hb_ot_math_constant_t constant)
{
return font->face->table.MATH->get_constant(constant, font);
}
/**
* hb_ot_math_get_glyph_italics_correction:
* @font: #hb_font_t to work upon
* @glyph: The glyph index from which to retrieve the value
*
* Fetches an italics-correction value (if one exists) for the specified
* glyph index.
*
* Return value: the italics correction of the glyph or zero
*
* Since: 1.3.3
**/
hb_position_t
hb_ot_math_get_glyph_italics_correction (hb_font_t *font,
hb_codepoint_t glyph)
{
return font->face->table.MATH->get_glyph_info().get_italics_correction (glyph, font);
}
/**
* hb_ot_math_get_glyph_top_accent_attachment:
* @font: #hb_font_t to work upon
* @glyph: The glyph index from which to retrieve the value
*
* Fetches a top-accent-attachment value (if one exists) for the specified
* glyph index.
*
* For any glyph that does not have a top-accent-attachment value - that is,
* a glyph not covered by the `MathTopAccentAttachment` table (or, when
* @font has no `MathTopAccentAttachment` table or no `MATH` table, any
* glyph) - the function synthesizes a value, returning the position at
* one-half the glyph's advance width.
*
* Return value: the top accent attachment of the glyph or 0.5 * the advance
* width of @glyph
*
* Since: 1.3.3
**/
hb_position_t
hb_ot_math_get_glyph_top_accent_attachment (hb_font_t *font,
hb_codepoint_t glyph)
{
return font->face->table.MATH->get_glyph_info().get_top_accent_attachment (glyph, font);
}
/**
* hb_ot_math_is_glyph_extended_shape:
* @face: #hb_face_t to work upon
* @glyph: The glyph index to test
*
* Tests whether the given glyph index is an extended shape in the face.
*
* Return value: `true` if the glyph is an extended shape, `false` otherwise
*
* Since: 1.3.3
**/
hb_bool_t
hb_ot_math_is_glyph_extended_shape (hb_face_t *face,
hb_codepoint_t glyph)
{
return face->table.MATH->get_glyph_info().is_extended_shape (glyph);
}
/**
* hb_ot_math_get_glyph_kerning:
* @font: #hb_font_t to work upon
* @glyph: The glyph index from which to retrieve the value
* @kern: The #hb_ot_math_kern_t from which to retrieve the value
* @correction_height: the correction height to use to determine the kerning.
*
* Fetches the math kerning (cut-ins) value for the specified font, glyph index, and
* @kern.
*
* If the MathKern table is found, the function examines it to find a height
* value that is greater or equal to @correction_height. If such a height
* value is found, corresponding kerning value from the table is returned. If
* no such height value is found, the last kerning value is returned.
*
* Return value: requested kerning value or zero
*
* Since: 1.3.3
**/
hb_position_t
hb_ot_math_get_glyph_kerning (hb_font_t *font,
hb_codepoint_t glyph,
hb_ot_math_kern_t kern,
hb_position_t correction_height)
{
return font->face->table.MATH->get_glyph_info().get_kerning (glyph,
kern,
correction_height,
font);
}
/**
* hb_ot_math_get_glyph_kernings:
* @font: #hb_font_t to work upon
* @glyph: The glyph index from which to retrieve the kernings
* @kern: The #hb_ot_math_kern_t from which to retrieve the kernings
* @start_offset: offset of the first kern entry to retrieve
* @entries_count: (inout) (optional): Input = the maximum number of kern entries to return;
* Output = the actual number of kern entries returned
* @kern_entries: (out caller-allocates) (array length=entries_count): array of kern entries returned
*
* Fetches the raw MathKern (cut-in) data for the specified font, glyph index,
* and @kern. The corresponding list of kern values and correction heights is
* returned as a list of #hb_ot_math_kern_entry_t structs.
*
* See also #hb_ot_math_get_glyph_kerning, which handles selecting the
* appropriate kern value for a given correction height.
*
* <note>For a glyph with @n defined kern values (where @n > 0), there are only
* @n1 defined correction heights, as each correction height defines a boundary
* past which the next kern value should be selected. Therefore, only the
* #hb_ot_math_kern_entry_t.kern_value of the uppermost #hb_ot_math_kern_entry_t
* actually comes from the font; its corresponding
* #hb_ot_math_kern_entry_t.max_correction_height is always set to
* <code>INT32_MAX</code>.</note>
*
* Return value: the total number of kern values available or zero
*
* Since: 3.4.0
**/
unsigned int
hb_ot_math_get_glyph_kernings (hb_font_t *font,
hb_codepoint_t glyph,
hb_ot_math_kern_t kern,
unsigned int start_offset,
unsigned int *entries_count, /* IN/OUT */
hb_ot_math_kern_entry_t *kern_entries /* OUT */)
{
return font->face->table.MATH->get_glyph_info().get_kernings (glyph,
kern,
start_offset,
entries_count,
kern_entries,
font);
}
/**
* hb_ot_math_get_glyph_variants:
* @font: #hb_font_t to work upon
* @glyph: The index of the glyph to stretch
* @direction: The direction of the stretching (horizontal or vertical)
* @start_offset: offset of the first variant to retrieve
* @variants_count: (inout): Input = the maximum number of variants to return;
* Output = the actual number of variants returned
* @variants: (out) (array length=variants_count): array of variants returned
*
* Fetches the MathGlyphConstruction for the specified font, glyph index, and
* direction. The corresponding list of size variants is returned as a list of
* #hb_ot_math_glyph_variant_t structs.
*
* <note>The @direction parameter is only used to select between horizontal
* or vertical directions for the construction. Even though all #hb_direction_t
* values are accepted, only the result of #HB_DIRECTION_IS_HORIZONTAL is
* considered.</note>
*
* Return value: the total number of size variants available or zero
*
* Since: 1.3.3
**/
unsigned int
hb_ot_math_get_glyph_variants (hb_font_t *font,
hb_codepoint_t glyph,
hb_direction_t direction,
unsigned int start_offset,
unsigned int *variants_count, /* IN/OUT */
hb_ot_math_glyph_variant_t *variants /* OUT */)
{
return font->face->table.MATH->get_variants().get_glyph_variants (glyph, direction, font,
start_offset,
variants_count,
variants);
}
/**
* hb_ot_math_get_min_connector_overlap:
* @font: #hb_font_t to work upon
* @direction: direction of the stretching (horizontal or vertical)
*
* Fetches the MathVariants table for the specified font and returns the
* minimum overlap of connecting glyphs that are required to draw a glyph
* assembly in the specified direction.
*
* <note>The @direction parameter is only used to select between horizontal
* or vertical directions for the construction. Even though all #hb_direction_t
* values are accepted, only the result of #HB_DIRECTION_IS_HORIZONTAL is
* considered.</note>
*
* Return value: requested minimum connector overlap or zero
*
* Since: 1.3.3
**/
hb_position_t
hb_ot_math_get_min_connector_overlap (hb_font_t *font,
hb_direction_t direction)
{
return font->face->table.MATH->get_variants().get_min_connector_overlap (direction, font);
}
/**
* hb_ot_math_get_glyph_assembly:
* @font: #hb_font_t to work upon
* @glyph: The index of the glyph to stretch
* @direction: direction of the stretching (horizontal or vertical)
* @start_offset: offset of the first glyph part to retrieve
* @parts_count: (inout): Input = maximum number of glyph parts to return;
* Output = actual number of parts returned
* @parts: (out) (array length=parts_count): the glyph parts returned
* @italics_correction: (out): italics correction of the glyph assembly
*
* Fetches the GlyphAssembly for the specified font, glyph index, and direction.
* Returned are a list of #hb_ot_math_glyph_part_t glyph parts that can be
* used to draw the glyph and an italics-correction value (if one is defined
* in the font).
*
* <note>The @direction parameter is only used to select between horizontal
* or vertical directions for the construction. Even though all #hb_direction_t
* values are accepted, only the result of #HB_DIRECTION_IS_HORIZONTAL is
* considered.</note>
*
* Return value: the total number of parts in the glyph assembly
*
* Since: 1.3.3
**/
unsigned int
hb_ot_math_get_glyph_assembly (hb_font_t *font,
hb_codepoint_t glyph,
hb_direction_t direction,
unsigned int start_offset,
unsigned int *parts_count, /* IN/OUT */
hb_ot_math_glyph_part_t *parts, /* OUT */
hb_position_t *italics_correction /* OUT */)
{
return font->face->table.MATH->get_variants().get_glyph_parts (glyph,
direction,
font,
start_offset,
parts_count,
parts,
italics_correction);
}
#endif