cdf/src/old/gradient.js

A library for creating oldschool demo-like animations with JavaScript

/* drawing gradients */

(function (global) {
  var lib = global.cdf || {};

  var grad = lib.gradient = lib.Gradient = lib.grad = function (dst, gradParams) {
    if(!(this instanceof lib.Gradient)){
      return new grad(dst, gradParams);
    }
    if(dst && dst.ctx){
      this.canvas = dst;
      this.params = gradParams;
    } else {
      this.canvas = new lib.Canvas(100,100);
      this.params = dst;
    }
    if(typeof this.params[0] === 'string') this.params = grad.interpolateColors(this.params);
  };

  grad.interpolateColors = function(colors){
    var gradParams = [];
    colors.forEach(function(color,index,all){
      gradParams.push({color:color, offset:index/(all.length-1)});
    });
    return gradParams;
  };

  grad.prototype = {
    getFillStyle: function(x0,y0,x1,y1){
      var lingrad = this.canvas.ctx.createLinearGradient(x0, y0, x1, y1);
      for (var j = 0; j < this.params.length; j++) {
        lingrad.addColorStop(this.params[j].offset, this.params[j].color);
      }
      return lingrad;
    },
    draw: function(x0,y0,x1,y1){
      this.canvas.fill(this.getFillStyle(x0,y0,x1,y1));
      return this;
    },
    drawV: function () { return this.draw(0, 0, this.canvas.w, 0); },
    drawH: function(){ return this.draw(0,0,0,this.canvas.h);},
    drawAngle: function (angleInDeg, cx,cy, length) {
      var dst = this.canvas;
      cx = cx === undefined? dst.cx : cx;
      cy = cy === undefined? dst.cy : cy;
      var r = length/2 || Math.sqrt(dst.cy*dst.cy+dst.cx*dst.cx);
      var angle = angleInDeg * lib.utils.DEG_TO_RAD;
      this.draw(Math.sin(angle)*r+cx,Math.cos(angle)*r+cy,Math.sin(angle+Math.PI)*r+cx,Math.cos(angle+Math.PI)*r+cy);
    }
  };

  if(typeof module!=='undefined'&& module.exports){module.exports=lib;}else{global.cdf=lib;}
})(window);