cdf/src/old/bitmap.js

A library for creating oldschool demo-like animations with JavaScript

(function(global,cdf_varname){var lib = global[cdf_varname] || {};

  var encodeNumber = function(num){
    return (0+num).toString(26).split('').map(function(num){
      var cc = num.charCodeAt(0);
      return String.fromCharCode(cc+(cc<=57 ?49:10));
    }).join('');
  };

  var decodeNumber = function(str){
    return parseInt(str.split('').map(function(s){
      var n = s.charCodeAt(0);
      return String.fromCharCode((n-10<97)?n-49:n-10);
    }).join(''),26)
  };

  lib.map = {
    /**
     * Draw a bit sequence onto canvas
     * @param {cdf.Canvas} canvas c0deff canvas to draw bit sequence onto
     * @param {string} bits  A string of bits. For example, 0110
     * @param {CanvasRenderingContext2D.fillStyle} fillStyle A fillstyle to put non-empty bits with
     */
    draw: function(canvas, bits, fillStyle, invert){
      bits = bits.split('')
      bits.forEach(function(b,n){
        if((b==0 && !invert) || (b!=0 && invert))return;
        x = n%canvas.width;
        y = Math.floor(n/canvas.width);
        canvas.plot(x,y,1,fillStyle);
      })
    },
    /**
     * Turns bit sequence to map
     * @param {string} bits A string of bits. For example, 0000110100100111111111100000000000000001101
     * @return {string} A map, for example (4)2#1##1##10(16)2#1
     */
    bitsToMap: function(bits){
      return bits
        .replace(/(0+)/g,function(a){return encodeNumber(a.length)})
        .replace(/(1+)/g,function(a){return a.length});
    },
    /**
     * Turns map to bit sequence
     * @param {string} map A map, for example (4)2#1##1##10(16)2#1
     * @return {string} A string of bits. For example, 0000110100100111111111100000000000000001101
     */
    mapToBits: function(map){
      return map
        .replace(/\d+/g,function(a){return '1'.repeat(a)})
        .replace(/[a-z]+/g,function(a){return '0'.repeat(decodeNumber(a))})
    },
    /**
     * Create new canvas and draw a bit sequence onto it
     * @param {int} width
     * @param {int} height
     * @param {string} bits
     * @param {CanvasRenderingContext2D.fillStyle} fillStyle A fillstyle to put non-empty bits with
     * @return {lib.canvas} Canvas filled with pattern
     */
    c: function(width, height, bits, fillStyle){
      var c = new lib.Canvas(width,height);
      if(bits.match(/[a-z]/))bits = this.mapToBits(bits);
      this.draw(c, bits, fillStyle);
      return c;
    }
  }

if(cdf_varname) global[cdf_varname]=lib;})(window, (typeof module!=='undefined'&& module.exports)?false:'cdf');