274 lines
14 KiB
C#
274 lines
14 KiB
C#
// Copyright (c) Six Labors.
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// Licensed under the Six Labors Split License.
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using System;
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using System.Text;
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namespace SixLabors.Fonts.Tables.General.Post {
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/// <summary>
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/// Represents the OpenType 'post' table, which contains information needed
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/// to use a font on a PostScript printer, including glyph names.
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/// <see href="https://learn.microsoft.com/en-us/typography/opentype/spec/post"/>
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/// </summary>
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internal class PostTable : Table
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{
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/// <summary>
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/// The table tag name identifying the 'post' table.
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/// </summary>
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internal const string TableName = "post";
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/// <summary>
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/// The standard Macintosh glyph name ordering for the first 258 glyph indices.
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/// </summary>
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private static readonly string[] AppleGlyphNameMap
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= new[]
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{
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".notdef", ".null", "nonmarkingreturn", "space", "exclam", "quotedbl", "numbersign", "dollar", "percent", "ampersand", "quotesingle", "parenleft", "parenright",
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"asterisk", "plus", "comma", "hyphen", "period", "slash", "zero", "one", "two", "three", "four", "five", "six", "seven", "eight", "nine", "colon", "semicolon",
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"less", "equal", "greater", "question", "at", "A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M", "N", "O", "P", "Q", "R", "S", "T", "U", "V", "W",
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"X", "Y", "Z", "bracketleft", "backslash", "bracketright", "asciicircum", "underscore", "grave", "a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l", "m",
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"n", "o", "p", "q", "r", "s", "t", "u", "v", "w", "x", "y", "z", "braceleft", "bar", "braceright", "asciitilde", "Adieresis", "Aring", "Ccedilla", "Eacute",
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"Ntilde", "Odieresis", "Udieresis", "aacute", "agrave", "acircumflex", "adieresis", "atilde", "aring", "ccedilla", "eacute", "egrave", "ecircumflex", "edieresis",
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"iacute", "igrave", "icircumflex", "idieresis", "ntilde", "oacute", "ograve", "ocircumflex", "odieresis", "otilde", "uacute", "ugrave", "ucircumflex", "udieresis",
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"dagger", "degree", "cent", "sterling", "section", "bullet", "paragraph", "germandbls", "registered", "copyright", "trademark", "acute", "dieresis", "notequal",
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"AE", "Oslash", "infinity", "plusminus", "lessequal", "greaterequal", "yen", "mu", "partialdiff", "summation", "product", "pi", "integral", "ordfeminine",
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"ordmasculine", "Omega", "ae", "oslash", "questiondown", "exclamdown", "logicalnot", "radical", "florin", "approxequal", "Delta", "guillemotleft", "guillemotright",
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"ellipsis", "nonbreakingspace", "Agrave", "Atilde", "Otilde", "OE", "oe", "endash", "emdash", "quotedblleft", "quotedblright", "quoteleft", "quoteright", "divide",
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"lozenge", "ydieresis", "Ydieresis", "fraction", "currency", "guilsinglleft", "guilsinglright", "fi", "fl", "daggerdbl", "periodcentered", "quotesinglbase", "quotedblbase",
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"perthousand", "Acircumflex", "Ecircumflex", "Aacute", "Edieresis", "Egrave", "Iacute", "Icircumflex", "Idieresis", "Igrave", "Oacute", "Ocircumflex", "apple", "Ograve",
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"Uacute", "Ucircumflex", "Ugrave", "dotlessi", "circumflex", "tilde", "macron", "breve", "dotaccent", "ring", "cedilla", "hungarumlaut", "ogonek", "caron", "Lslash",
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"lslash", "Scaron", "scaron", "Zcaron", "zcaron", "brokenbar", "Eth", "eth", "Yacute", "yacute", "Thorn", "thorn", "minus", "multiply", "onesuperior", "twosuperior",
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"threesuperior", "onehalf", "onequarter", "threequarters", "franc", "Gbreve", "gbreve", "Idotaccent", "Scedilla", "scedilla", "Cacute", "cacute", "Ccaron", "ccaron", "dcroat"
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};
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/// <summary>
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/// Initializes a new instance of the <see cref="PostTable"/> class.
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/// </summary>
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/// <param name="formatMajor">The major version of the post table format.</param>
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/// <param name="formatMinor">The minor version of the post table format.</param>
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/// <param name="underlinePosition">The suggested distance of the top of the underline from the baseline.</param>
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/// <param name="underlineThickness">The suggested underline thickness.</param>
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/// <param name="italicAngle">The italic angle in counter-clockwise degrees from the vertical.</param>
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/// <param name="isFixedPitch">Non-zero if the font is monospaced; zero if proportionally spaced.</param>
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/// <param name="minMemType42">The minimum memory usage when downloaded as a Type 42 font.</param>
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/// <param name="maxMemType42">The maximum memory usage when downloaded as a Type 42 font.</param>
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/// <param name="minMemType1">The minimum memory usage when downloaded as a Type 1 font.</param>
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/// <param name="maxMemType1">The maximum memory usage when downloaded as a Type 1 font.</param>
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/// <param name="postRecords">The array of post name records for glyph name mapping.</param>
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public PostTable(
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ushort formatMajor,
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ushort formatMinor,
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short underlinePosition,
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short underlineThickness,
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float italicAngle,
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uint isFixedPitch,
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uint minMemType42,
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uint maxMemType42,
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uint minMemType1,
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uint maxMemType1,
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PostNameRecord[] postRecords)
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{
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this.FormatMajor = formatMajor;
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this.FormatMinor = formatMinor;
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this.UnderlinePosition = underlinePosition;
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this.UnderlineThickness = underlineThickness;
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this.ItalicAngle = italicAngle;
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this.IsFixedPitch = isFixedPitch;
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this.MinMemType42 = minMemType42;
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this.MaxMemType42 = maxMemType42;
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this.MinMemType1 = minMemType1;
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this.MaxMemType1 = maxMemType1;
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this.PostRecords = postRecords;
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}
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/// <summary>
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/// Gets the array of post name records mapping glyph indices to PostScript names.
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/// </summary>
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public PostNameRecord[] PostRecords { get; }
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/// <summary>
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/// Gets the major version number of the post table format.
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/// </summary>
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public ushort FormatMajor { get; }
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/// <summary>
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/// Gets the minor version number of the post table format.
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/// </summary>
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public ushort FormatMinor { get; }
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/// <summary>
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/// Gets the suggested distance of the top of the underline from the baseline, in font design units.
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/// Negative values indicate below baseline.
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/// </summary>
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public short UnderlinePosition { get; }
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/// <summary>
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/// Gets the suggested underline thickness, in font design units.
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/// </summary>
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public short UnderlineThickness { get; }
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/// <summary>
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/// Gets the italic angle in counter-clockwise degrees from the vertical.
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/// Zero for upright text, negative for text that leans to the right.
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/// </summary>
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public float ItalicAngle { get; }
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/// <summary>
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/// Gets a value indicating whether the font is monospaced.
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/// Non-zero if the font is not proportionally spaced (i.e., monospaced).
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/// </summary>
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public uint IsFixedPitch { get; }
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/// <summary>
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/// Gets the minimum memory usage when an OpenType font is downloaded as a Type 42 font.
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/// </summary>
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public uint MinMemType42 { get; }
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/// <summary>
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/// Gets the maximum memory usage when an OpenType font is downloaded as a Type 42 font.
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/// </summary>
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public uint MaxMemType42 { get; }
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/// <summary>
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/// Gets the minimum memory usage when an OpenType font is downloaded as a Type 1 font.
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/// </summary>
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public uint MinMemType1 { get; }
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/// <summary>
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/// Gets the maximum memory usage when an OpenType font is downloaded as a Type 1 font.
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/// </summary>
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public uint MaxMemType1 { get; }
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/// <summary>
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/// Loads the <see cref="PostTable"/> from the specified font reader.
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/// </summary>
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/// <param name="fontReader">The font reader to read the table from.</param>
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/// <returns>The loaded <see cref="PostTable"/>, or <see langword="null"/> if the table is not present.</returns>
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public static PostTable? Load(FontReader fontReader)
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{
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if (!fontReader.TryGetReaderAtTablePosition(TableName, out BigEndianBinaryReader? binaryReader))
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{
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return null;
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}
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using (binaryReader)
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{
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return Load(binaryReader);
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}
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}
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/// <summary>
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/// Loads the <see cref="PostTable"/> from the specified binary reader.
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/// </summary>
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/// <param name="reader">The binary reader positioned at the start of the post table data.</param>
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/// <returns>The loaded <see cref="PostTable"/>.</returns>
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/// <exception cref="NotSupportedException">Thrown when the table format version is not supported.</exception>
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public static PostTable Load(BigEndianBinaryReader reader)
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{
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// HEADER
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// Type | Name | Description
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// ----------------|---------------------|---------------------------------------------------------------
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// Version16Dot16 | version | 0x00010000 for version 1.0, 0x00020000 for version 2.0, 0x00025000 for version 2.5 (deprecated), 0x00030000 for version 3.0
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// Fixed | italicAngle | Italic angle in counter-clockwise degrees from the vertical. Zero for upright text, negative for text that leans to the right (forward).
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// FWORD | underlinePosition | This is the suggested distance of the top of the underline from the baseline (negative values indicate below baseline). The PostScript definition of this FontInfo dictionary key (the y coordinate of the center of the stroke) is not used for historical reasons. The value of the PostScript key may be calculated by subtracting half the underlineThickness from the value of this field.
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// FWORD | underlineThickness | Suggested values for the underline thickness. In general, the underline thickness should match the thickness of the underscore character (U+005F LOW LINE), and should also match the strikeout thickness, which is specified in the OS/2 table.
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// uint32 | isFixedPitch | Set to 0 if the font is proportionally spaced, non-zero if the font is not proportionally spaced (i.e. monospaced).
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// uint32 | minMemType42 | Minimum memory usage when an OpenType font is downloaded.
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// uint32 | maxMemType42 | Maximum memory usage when an OpenType font is downloaded.
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// uint32 | minMemType1 | Minimum memory usage when an OpenType font is downloaded as a Type 1 font.
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// uint32 | maxMemType1 | Maximum memory usage when an OpenType font is downloaded as a Type 1 font.
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// FORMAT 2.0
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// Type | Name | Description
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// --------|-----------------------------|--------------------------------------------------------------
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// uint16 | numGlyphs | Number of glyphs (this should be the same as numGlyphs in 'maxp' table).
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// uint16 | glyphNameIndex[numGlyphs] | Array of indices into the string data. See below for details.
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// uint8 | stringData[variable] | Storage for the string data.
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ushort formatMajor = reader.ReadUInt16();
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ushort formatMinor = reader.ReadUInt16();
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float italicAngle = reader.ReadFixed();
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short underlinePosition = reader.ReadFWORD();
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short underlineThickness = reader.ReadFWORD();
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uint isFixedPitch = reader.ReadUInt32();
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uint minMemType42 = reader.ReadUInt32();
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uint maxMemType42 = reader.ReadUInt32();
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uint minMemType1 = reader.ReadUInt32();
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uint maxMemType1 = reader.ReadUInt32();
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PostNameRecord[] records = Array.Empty<PostNameRecord>();
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if (formatMajor == 1)
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{
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// Supported, no extra subtables needed
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}
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else if (formatMajor == 2 && formatMinor == 0)
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{
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ushort numGlyphs = reader.ReadUInt16();
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records = new PostNameRecord[numGlyphs];
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ushort[] glyphIndices = reader.ReadUInt16Array(numGlyphs);
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for (int i = 0; i < numGlyphs; i++)
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{
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ushort glyphNameIndex = glyphIndices[i];
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string name;
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// < 258 is a standard fixed apple mapping
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if (glyphNameIndex <= 257)
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{
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name = AppleGlyphNameMap[glyphNameIndex];
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}
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else
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{
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byte strLength = reader.ReadByte();
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name = reader.ReadString(strLength, Encoding.ASCII);
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}
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records[i] = new PostNameRecord(glyphNameIndex, name);
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}
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}
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else if (formatMajor > 3)
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{
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throw new NotSupportedException($"{TableName} table format {formatMajor}.{formatMinor} is not supported.");
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}
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// TODO: Validate maximum numbers against maxp table.
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return new PostTable(
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formatMajor,
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formatMinor,
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underlinePosition,
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underlineThickness,
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italicAngle,
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isFixedPitch,
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minMemType42,
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maxMemType42,
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minMemType1,
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maxMemType1,
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records);
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}
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/// <summary>
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/// Gets the PostScript name for the glyph at the specified name index.
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/// </summary>
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/// <param name="nameIndex">The name index to look up.</param>
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/// <returns>The PostScript glyph name, or <see langword="null"/> if not found.</returns>
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public string? GetPostScriptName(int nameIndex)
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{
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if (this.PostRecords is not null)
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{
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for (int i = 0; i < this.PostRecords.Length; i++)
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{
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PostNameRecord p = this.PostRecords[i];
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if (p.NameIndex == nameIndex)
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{
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return p.Name;
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}
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}
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}
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return null;
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}
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}
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}
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