add initial marp implementation with sample content and build configuration
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// @flow
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import {supportedCodepoint} from "./unicodeScripts";
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import type {Mode} from "./types";
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/**
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* This file contains metrics regarding fonts and individual symbols. The sigma
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* and xi variables, as well as the metricMap map contain data extracted from
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* TeX, TeX font metrics, and the TTF files. These data are then exposed via the
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* `metrics` variable and the getCharacterMetrics function.
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*/
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// In TeX, there are actually three sets of dimensions, one for each of
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// textstyle (size index 5 and higher: >=9pt), scriptstyle (size index 3 and 4:
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// 7-8pt), and scriptscriptstyle (size index 1 and 2: 5-6pt). These are
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// provided in the arrays below, in that order.
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//
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// The font metrics are stored in fonts cmsy10, cmsy7, and cmsy5 respectively.
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// This was determined by running the following script:
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//
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// latex -interaction=nonstopmode \
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// '\documentclass{article}\usepackage{amsmath}\begin{document}' \
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// '$a$ \expandafter\show\the\textfont2' \
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// '\expandafter\show\the\scriptfont2' \
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// '\expandafter\show\the\scriptscriptfont2' \
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// '\stop'
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//
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// The metrics themselves were retrieved using the following commands:
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//
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// tftopl cmsy10
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// tftopl cmsy7
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// tftopl cmsy5
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//
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// The output of each of these commands is quite lengthy. The only part we
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// care about is the FONTDIMEN section. Each value is measured in EMs.
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const sigmasAndXis = {
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slant: [0.250, 0.250, 0.250], // sigma1
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space: [0.000, 0.000, 0.000], // sigma2
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stretch: [0.000, 0.000, 0.000], // sigma3
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shrink: [0.000, 0.000, 0.000], // sigma4
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xHeight: [0.431, 0.431, 0.431], // sigma5
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quad: [1.000, 1.171, 1.472], // sigma6
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extraSpace: [0.000, 0.000, 0.000], // sigma7
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num1: [0.677, 0.732, 0.925], // sigma8
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num2: [0.394, 0.384, 0.387], // sigma9
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num3: [0.444, 0.471, 0.504], // sigma10
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denom1: [0.686, 0.752, 1.025], // sigma11
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denom2: [0.345, 0.344, 0.532], // sigma12
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sup1: [0.413, 0.503, 0.504], // sigma13
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sup2: [0.363, 0.431, 0.404], // sigma14
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sup3: [0.289, 0.286, 0.294], // sigma15
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sub1: [0.150, 0.143, 0.200], // sigma16
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sub2: [0.247, 0.286, 0.400], // sigma17
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supDrop: [0.386, 0.353, 0.494], // sigma18
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subDrop: [0.050, 0.071, 0.100], // sigma19
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delim1: [2.390, 1.700, 1.980], // sigma20
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delim2: [1.010, 1.157, 1.420], // sigma21
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axisHeight: [0.250, 0.250, 0.250], // sigma22
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// These font metrics are extracted from TeX by using tftopl on cmex10.tfm;
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// they correspond to the font parameters of the extension fonts (family 3).
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// See the TeXbook, page 441. In AMSTeX, the extension fonts scale; to
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// match cmex7, we'd use cmex7.tfm values for script and scriptscript
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// values.
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defaultRuleThickness: [0.04, 0.049, 0.049], // xi8; cmex7: 0.049
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bigOpSpacing1: [0.111, 0.111, 0.111], // xi9
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bigOpSpacing2: [0.166, 0.166, 0.166], // xi10
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bigOpSpacing3: [0.2, 0.2, 0.2], // xi11
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bigOpSpacing4: [0.6, 0.611, 0.611], // xi12; cmex7: 0.611
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bigOpSpacing5: [0.1, 0.143, 0.143], // xi13; cmex7: 0.143
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// The \sqrt rule width is taken from the height of the surd character.
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// Since we use the same font at all sizes, this thickness doesn't scale.
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sqrtRuleThickness: [0.04, 0.04, 0.04],
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// This value determines how large a pt is, for metrics which are defined
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// in terms of pts.
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// This value is also used in katex.scss; if you change it make sure the
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// values match.
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ptPerEm: [10.0, 10.0, 10.0],
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// The space between adjacent `|` columns in an array definition. From
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// `\showthe\doublerulesep` in LaTeX. Equals 2.0 / ptPerEm.
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doubleRuleSep: [0.2, 0.2, 0.2],
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// The width of separator lines in {array} environments. From
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// `\showthe\arrayrulewidth` in LaTeX. Equals 0.4 / ptPerEm.
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arrayRuleWidth: [0.04, 0.04, 0.04],
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// Two values from LaTeX source2e:
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fboxsep: [0.3, 0.3, 0.3], // 3 pt / ptPerEm
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fboxrule: [0.04, 0.04, 0.04], // 0.4 pt / ptPerEm
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};
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// This map contains a mapping from font name and character code to character
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// metrics, including height, depth, italic correction, and skew (kern from the
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// character to the corresponding \skewchar)
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// This map is generated via `make metrics`. It should not be changed manually.
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import metricMap from "./fontMetricsData";
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// These are very rough approximations. We default to Times New Roman which
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// should have Latin-1 and Cyrillic characters, but may not depending on the
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// operating system. The metrics do not account for extra height from the
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// accents. In the case of Cyrillic characters which have both ascenders and
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// descenders we prefer approximations with ascenders, primarily to prevent
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// the fraction bar or root line from intersecting the glyph.
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// TODO(kevinb) allow union of multiple glyph metrics for better accuracy.
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const extraCharacterMap = {
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// Latin-1
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'Å': 'A',
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'Ð': 'D',
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'Þ': 'o',
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'å': 'a',
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'ð': 'd',
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'þ': 'o',
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// Cyrillic
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'А': 'A',
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'Б': 'B',
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'В': 'B',
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'Г': 'F',
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'Д': 'A',
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'Е': 'E',
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'Ж': 'K',
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'З': '3',
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'И': 'N',
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'Й': 'N',
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'К': 'K',
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'Л': 'N',
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'М': 'M',
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'Н': 'H',
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'О': 'O',
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'П': 'N',
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'Р': 'P',
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'С': 'C',
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'Т': 'T',
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'У': 'y',
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'Ф': 'O',
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'Х': 'X',
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'Ц': 'U',
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'Ч': 'h',
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'Ш': 'W',
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'Щ': 'W',
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'Ъ': 'B',
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'Ы': 'X',
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'Ь': 'B',
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'Э': '3',
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'Ю': 'X',
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'Я': 'R',
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'а': 'a',
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'б': 'b',
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'в': 'a',
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'г': 'r',
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'д': 'y',
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'е': 'e',
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'ж': 'm',
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'з': 'e',
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'и': 'n',
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'й': 'n',
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'к': 'n',
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'л': 'n',
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'м': 'm',
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'н': 'n',
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'о': 'o',
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'п': 'n',
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'р': 'p',
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'с': 'c',
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'т': 'o',
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'у': 'y',
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'ф': 'b',
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'х': 'x',
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'ц': 'n',
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'ч': 'n',
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'ш': 'w',
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'щ': 'w',
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'ъ': 'a',
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'ы': 'm',
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'ь': 'a',
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'э': 'e',
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'ю': 'm',
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'я': 'r',
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};
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export type CharacterMetrics = {
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depth: number;
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height: number;
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italic: number;
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skew: number;
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width: number;
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};
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export type MetricMap = {
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[string]: number[]
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}
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/**
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* This function adds new font metrics to default metricMap
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* It can also override existing metrics
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*/
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export function setFontMetrics(fontName: string, metrics: MetricMap) {
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metricMap[fontName] = metrics;
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}
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/**
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* This function is a convenience function for looking up information in the
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* metricMap table. It takes a character as a string, and a font.
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*
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* Note: the `width` property may be undefined if fontMetricsData.js wasn't
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* built using `Make extended_metrics`.
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*/
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export function getCharacterMetrics(
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character: string,
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font: string,
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mode: Mode,
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): ?CharacterMetrics {
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if (!metricMap[font]) {
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throw new Error(`Font metrics not found for font: ${font}.`);
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}
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let ch = character.charCodeAt(0);
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let metrics = metricMap[font][ch];
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if (!metrics && character[0] in extraCharacterMap) {
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ch = extraCharacterMap[character[0]].charCodeAt(0);
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metrics = metricMap[font][ch];
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}
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if (!metrics && mode === 'text') {
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// We don't typically have font metrics for Asian scripts.
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// But since we support them in text mode, we need to return
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// some sort of metrics.
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// So if the character is in a script we support but we
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// don't have metrics for it, just use the metrics for
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// the Latin capital letter M. This is close enough because
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// we (currently) only care about the height of the glyph
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// not its width.
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if (supportedCodepoint(ch)) {
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metrics = metricMap[font][77]; // 77 is the charcode for 'M'
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}
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}
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if (metrics) {
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return {
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depth: metrics[0],
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height: metrics[1],
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italic: metrics[2],
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skew: metrics[3],
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width: metrics[4],
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};
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}
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}
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type FontSizeIndex = 0 | 1 | 2;
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export type FontMetrics = {
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cssEmPerMu: number,
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[string]: number,
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};
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const fontMetricsBySizeIndex: {[FontSizeIndex]: FontMetrics} = {};
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/**
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* Get the font metrics for a given size.
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*/
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export function getGlobalMetrics(size: number): FontMetrics {
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let sizeIndex: FontSizeIndex;
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if (size >= 5) {
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sizeIndex = 0;
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} else if (size >= 3) {
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sizeIndex = 1;
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} else {
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sizeIndex = 2;
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}
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if (!fontMetricsBySizeIndex[sizeIndex]) {
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const metrics = fontMetricsBySizeIndex[sizeIndex] = {
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cssEmPerMu: sigmasAndXis.quad[sizeIndex] / 18,
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};
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for (const key in sigmasAndXis) {
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if (sigmasAndXis.hasOwnProperty(key)) {
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metrics[key] = sigmasAndXis[key][sizeIndex];
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}
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}
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}
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return fontMetricsBySizeIndex[sizeIndex];
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}
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