www

Unnamed repository; edit this file 'description' to name the repository.
Log | Files | Refs | README

Style.js (3780B)

      1 /**
      2  * This file contains information and classes for the various kinds of styles
      3  * used in TeX. It provides a generic `Style` class, which holds information
      4  * about a specific style. It then provides instances of all the different kinds
      5  * of styles possible, and provides functions to move between them and get
      6  * information about them.
      7  */
      8 
      9 const sigmas = require("./fontMetrics.js").sigmas;
     10 
     11 const metrics = [{}, {}, {}];
     12 for (const key in sigmas) {
     13     if (sigmas.hasOwnProperty(key)) {
     14         for (let i = 0; i < 3; i++) {
     15             metrics[i][key] = sigmas[key][i];
     16         }
     17     }
     18 }
     19 for (let i = 0; i < 3; i++) {
     20     metrics[i].emPerEx = sigmas.xHeight[i] / sigmas.quad[i];
     21 }
     22 
     23 /**
     24  * The main style class. Contains a unique id for the style, a size (which is
     25  * the same for cramped and uncramped version of a style), a cramped flag, and a
     26  * size multiplier, which gives the size difference between a style and
     27  * textstyle.
     28  */
     29 function Style(id, size, multiplier, cramped) {
     30     this.id = id;
     31     this.size = size;
     32     this.cramped = cramped;
     33     this.sizeMultiplier = multiplier;
     34     this.metrics = metrics[size > 0 ? size - 1 : 0];
     35 }
     36 
     37 /**
     38  * Get the style of a superscript given a base in the current style.
     39  */
     40 Style.prototype.sup = function() {
     41     return styles[sup[this.id]];
     42 };
     43 
     44 /**
     45  * Get the style of a subscript given a base in the current style.
     46  */
     47 Style.prototype.sub = function() {
     48     return styles[sub[this.id]];
     49 };
     50 
     51 /**
     52  * Get the style of a fraction numerator given the fraction in the current
     53  * style.
     54  */
     55 Style.prototype.fracNum = function() {
     56     return styles[fracNum[this.id]];
     57 };
     58 
     59 /**
     60  * Get the style of a fraction denominator given the fraction in the current
     61  * style.
     62  */
     63 Style.prototype.fracDen = function() {
     64     return styles[fracDen[this.id]];
     65 };
     66 
     67 /**
     68  * Get the cramped version of a style (in particular, cramping a cramped style
     69  * doesn't change the style).
     70  */
     71 Style.prototype.cramp = function() {
     72     return styles[cramp[this.id]];
     73 };
     74 
     75 /**
     76  * HTML class name, like "displaystyle cramped"
     77  */
     78 Style.prototype.cls = function() {
     79     return sizeNames[this.size] + (this.cramped ? " cramped" : " uncramped");
     80 };
     81 
     82 /**
     83  * HTML Reset class name, like "reset-textstyle"
     84  */
     85 Style.prototype.reset = function() {
     86     return resetNames[this.size];
     87 };
     88 
     89 /**
     90  * Return if this style is tightly spaced (scriptstyle/scriptscriptstyle)
     91  */
     92 Style.prototype.isTight = function() {
     93     return this.size >= 2;
     94 };
     95 
     96 // IDs of the different styles
     97 const D = 0;
     98 const Dc = 1;
     99 const T = 2;
    100 const Tc = 3;
    101 const S = 4;
    102 const Sc = 5;
    103 const SS = 6;
    104 const SSc = 7;
    105 
    106 // String names for the different sizes
    107 const sizeNames = [
    108     "displaystyle textstyle",
    109     "textstyle",
    110     "scriptstyle",
    111     "scriptscriptstyle",
    112 ];
    113 
    114 // Reset names for the different sizes
    115 const resetNames = [
    116     "reset-textstyle",
    117     "reset-textstyle",
    118     "reset-scriptstyle",
    119     "reset-scriptscriptstyle",
    120 ];
    121 
    122 // Instances of the different styles
    123 const styles = [
    124     new Style(D, 0, 1.0, false),
    125     new Style(Dc, 0, 1.0, true),
    126     new Style(T, 1, 1.0, false),
    127     new Style(Tc, 1, 1.0, true),
    128     new Style(S, 2, 0.7, false),
    129     new Style(Sc, 2, 0.7, true),
    130     new Style(SS, 3, 0.5, false),
    131     new Style(SSc, 3, 0.5, true),
    132 ];
    133 
    134 // Lookup tables for switching from one style to another
    135 const sup = [S, Sc, S, Sc, SS, SSc, SS, SSc];
    136 const sub = [Sc, Sc, Sc, Sc, SSc, SSc, SSc, SSc];
    137 const fracNum = [T, Tc, S, Sc, SS, SSc, SS, SSc];
    138 const fracDen = [Tc, Tc, Sc, Sc, SSc, SSc, SSc, SSc];
    139 const cramp = [Dc, Dc, Tc, Tc, Sc, Sc, SSc, SSc];
    140 
    141 // We only export some of the styles. Also, we don't export the `Style` class so
    142 // no more styles can be generated.
    143 module.exports = {
    144     DISPLAY: styles[D],
    145     TEXT: styles[T],
    146     SCRIPT: styles[S],
    147     SCRIPTSCRIPT: styles[SS],
    148 };