JDK14/Java14源码在线阅读

/*
 * Copyright © 2010  Red Hat, Inc.
 * Copyright © 2012  Google, Inc.
 *
 *  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.
 *
 * Red Hat Author(s): Behdad Esfahbod
 * Google Author(s): Behdad Esfahbod
 */

#ifndef HB_OT_HEAD_TABLE_HH
#define HB_OT_HEAD_TABLE_HH

#include "hb-open-type.hh"

/*
 * head -- Font Header
 * https://docs.microsoft.com/en-us/typography/opentype/spec/head
 */
#define HB_OT_TAG_head HB_TAG('h','e','a','d')


namespace OT {


struct head
{
  friend struct OffsetTable;

  static constexpr hb_tag_t tableTag = HB_OT_TAG_head;

  unsigned int get_upem () const
  {
    unsigned int upem = unitsPerEm;
    /* If no valid head table found, assume 1000, which matches typical Type1 usage. */
    return 16 <= upem && upem <= 16384 ? upem : 1000;
  }

  enum mac_style_flag_t {
    BOLD        = 1u<<0,
    ITALIC      = 1u<<1,
    UNDERLINE   = 1u<<2,
    OUTLINE     = 1u<<3,
    SHADOW      = 1u<<4,
    CONDENSED   = 1u<<5
  };

  bool is_bold () const      { return macStyle & BOLD; }
  bool is_italic () const    { return macStyle & ITALIC; }
  bool is_condensed () const { return macStyle & CONDENSED; }

  bool sanitize (hb_sanitize_context_t *c) const
  {
    TRACE_SANITIZE (this);
    return_trace (c->check_struct (this) &&
                  version.major == 1 &&
                  magicNumber == 0x5F0F3CF5u);
  }

  protected:
  FixedVersion<>version;                /* Version of the head table--currently
                                         * 0x00010000u for version 1.0. */
  FixedVersion<>fontRevision;           /* Set by font manufacturer. */
  HBUINT32      checkSumAdjustment;     /* To compute: set it to 0, sum the
                                         * entire font as HBUINT32, then store
                                         * 0xB1B0AFBAu - sum. */
  HBUINT32      magicNumber;            /* Set to 0x5F0F3CF5u. */
  HBUINT16      flags;                  /* Bit 0: Baseline for font at y=0;
                                         * Bit 1: Left sidebearing point at x=0;
                                         * Bit 2: Instructions may depend on point size;
                                         * Bit 3: Force ppem to integer values for all
                                         *   internal scaler math; may use fractional
                                         *   ppem sizes if this bit is clear;
                                         * Bit 4: Instructions may alter advance width
                                         *   (the advance widths might not scale linearly);
                                         * Bits 5-10: These should be set according to
                                         *   Apple's specification. However, they are not
                                         *   implemented in OpenType.
                                         * Bit 5: This bit should be set in fonts that are
                                         *   intended to e laid out vertically, and in
                                         *   which the glyphs have been drawn such that an
                                         *   x-coordinate of 0 corresponds to the desired
                                         *   vertical baseline.
                                         * Bit 6: This bit must be set to zero.
                                         * Bit 7: This bit should be set if the font
                                         *   requires layout for correct linguistic
                                         *   rendering (e.g. Arabic fonts).
                                         * Bit 8: This bit should be set for a GX font
                                         *   which has one or more metamorphosis effects
                                         *   designated as happening by default.
                                         * Bit 9: This bit should be set if the font
                                         *   contains any strong right-to-left glyphs.
                                         * Bit 10: This bit should be set if the font
                                         *   contains Indic-style rearrangement effects.
                                         * Bit 11: Font data is 'lossless,' as a result
                                         *   of having been compressed and decompressed
                                         *   with the Agfa MicroType Express engine.
                                         * Bit 12: Font converted (produce compatible metrics)
                                         * Bit 13: Font optimized for ClearType™.
                                         *   Note, fonts that rely on embedded bitmaps (EBDT)
                                         *   for rendering should not be considered optimized
                                         *   for ClearType, and therefore should keep this bit
                                         *   cleared.
                                         * Bit 14: Last Resort font. If set, indicates that
                                         * the glyphs encoded in the cmap subtables are simply
                                         * generic symbolic representations of code point
                                         * ranges and don’t truly represent support for those
                                         * code points. If unset, indicates that the glyphs
                                         * encoded in the cmap subtables represent proper
                                         * support for those code points.
                                         * Bit 15: Reserved, set to 0. */
  HBUINT16      unitsPerEm;             /* Valid range is from 16 to 16384. This value
                                         * should be a power of 2 for fonts that have
                                         * TrueType outlines. */
  LONGDATETIME  created;                /* Number of seconds since 12:00 midnight,
                                           January 1, 1904. 64-bit integer */
  LONGDATETIME  modified;               /* Number of seconds since 12:00 midnight,
                                           January 1, 1904. 64-bit integer */
  HBINT16       xMin;                   /* For all glyph bounding boxes. */
  HBINT16       yMin;                   /* For all glyph bounding boxes. */
  HBINT16       xMax;                   /* For all glyph bounding boxes. */
  HBINT16       yMax;                   /* For all glyph bounding boxes. */
  HBUINT16      macStyle;               /* Bit 0: Bold (if set to 1);
                                         * Bit 1: Italic (if set to 1)
                                         * Bit 2: Underline (if set to 1)
                                         * Bit 3: Outline (if set to 1)
                                         * Bit 4: Shadow (if set to 1)
                                         * Bit 5: Condensed (if set to 1)

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