tor-browser

hb-ot-math.cc (12300B)

---

/*
* 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_RADICAL_DEGREE_BOTTOM_RAISE_PERCENT, 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)
{
 /* https://github.com/harfbuzz/harfbuzz/issues/4653
  * Cambria Math has incorrect value for displayOperatorMinHeight, and
  * apparently Microsoft implementation swaps displayOperatorMinHeight and
  * delimitedSubFormulaMinHeight, so we do the same if we detect Cambria Math
  * with the swapped values. */
 if ((constant == HB_OT_MATH_CONSTANT_DISPLAY_OPERATOR_MIN_HEIGHT ||
      constant == HB_OT_MATH_CONSTANT_DELIMITED_SUB_FORMULA_MIN_HEIGHT) &&
     font->face->table.MATH->is_bad_cambria (font))
 {
   if (constant == HB_OT_MATH_CONSTANT_DISPLAY_OPERATOR_MIN_HEIGHT)
     constant = HB_OT_MATH_CONSTANT_DELIMITED_SUB_FORMULA_MIN_HEIGHT;
   else
     constant = HB_OT_MATH_CONSTANT_DISPLAY_OPERATOR_MIN_HEIGHT;
 }
 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
* @n−1 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