git.kianting.info Git - clo/blob - src/libclo/breakLines.ts

   1 /**
   2  * Algorithms and functions for LineBreaking
   3  */
   4 import { join } from "path";
   5 import {BreakPoint, BoxesItem, HGlue} from "./index.js";
   6 /**
   7  * Algorithms in LATEX language
   8 TotalCost(i) = min_{j}~TotalCost(j) + LineCost(j, i)~~~~j=0, 1, ..., i-1
   9
  10 LineCost(j, i)= \begin{cases}
  11 \infty ~~~ if~~LineWidth - \sum_{k=j+1}^{i-1} OrigWidth(item[k]) - newLineWidth(item[i]) < 0 \\
  12 \infty~~if~~NOT~~breakable(item[i]) \\
  13 (LineWidth - \sum_{k=j+1}^{i-1} OrigWidth(item[k]) - newLineWidth(item[i]))^3 ~~elsewhere
  14 \end{cases} */
  15
  16 /**check if a boeitem is BreakPoint Type */
  17 function isBreakPoint (item : any) : item is BreakPoint{
  18     return (item as BreakPoint).newLined !== undefined;
  19 }
  20
  21 /**check if a boeitem is BreakPoint Type */
  22 function isHGlue (item : any) : item is HGlue{
  23     return (item as HGlue).stretchFactor !== undefined;
  24 }
  25
  26
  27 /** measuring original advance width */
  28 function origWidth(item : BoxesItem) : number{
  29     if (isBreakPoint(item)){
  30         console.log(item);
  31         return origWidth(item.original);
  32     }else if(Array.isArray(item)){
  33         return item.map((x)=>origWidth(x))
  34             .reduce((acc, current) => acc + current,
  35             0.0,)
  36     }else if(isHGlue(item)){
  37         return 0.0;
  38     }
  39     else{
  40         return item.width;
  41     }
  42 }
  43
  44 /** measuring new-line triggered advance width */
  45 function newLineWidth(item : BoxesItem) : number{
  46     if (isBreakPoint(item)){
  47         return origWidth(item.newLined);
  48     }else{
  49         // impossible to make a new line
  50         return Infinity;
  51     }
  52 }
  53
  54 let lineCostStorage : any = new Object();
  55
  56 /**
  57  * check the total cost item[0..j].
  58  * @param items
  59  * @param i
  60  * @param lineWidth
  61  */
  62 export function totalCost(items : BoxesItem[], j : number, lineWidth: number){
  63     if (j in lineCostStorage){
  64         return lineCostStorage[j];
  65     }
  66     var returnCost = Infinity;
  67
  68     for(var i=-1; i<=j; i++){
  69         // lineCost
  70         let lCost = lineCost(items, i, j, lineWidth);
  71
  72         if (returnCost > lCost){
  73             returnCost = lCost;
  74         }
  75     }
  76
  77     lineCostStorage[j] = returnCost;
  78     return returnCost;
  79
  80 }
  81
  82
  83
  84 /**
  85  * check the line cost of a line containing items[i+1..j]
  86  * @param items items of box
  87  * @param i beginning (excluded)
  88  * @param j end of the line
  89  * @param lineWidth line width
  90  */
  91 function lineCost(items : BoxesItem[], i : number, j : number, lineWidth: number){
  92     if (!isBreakPoint(items[j])){
  93         return Infinity;
  94     }else{
  95         var tmpItemWidth = 0;
  96         for (var k = i+1; k<j; k++){
  97             tmpItemWidth += origWidth(items[k]);
  98         }
  99
 100         tmpItemWidth += newLineWidth(items[j]);
 101
 102         if (tmpItemWidth > lineWidth){
 103             return Infinity;
 104         }else{
 105             return (lineWidth - tmpItemWidth)**3.0;
 106         }
 107     }
 108
 109 }