lkarch.org/tools/hexgl/bkcore.coffee/ImageData.js

// Generated by CoffeeScript 1.4.0

/*
  Loads an image and gives access to pixel data.
  
  @class bkcore.ImageData
  @author Thibaut 'BKcore' Despoulain <http://bkcore.com>
*/


(function() {
  var ImageData, exports;

  ImageData = (function() {
    /*
        Creates a new ImageData object
        
        @param path string The path of the image
        @param callback function A callback function to be called
          once th eimage is loaded
    */

    function ImageData(path, callback) {
      var _this = this;
      this.image = new Image;
      this.pixels = null;
      this.canvas = null;
      this.loaded = false;
      this.image.onload = function() {
        var context;
        _this.canvas = document.createElement('canvas');
        _this.canvas.width = _this.image.width;
        _this.canvas.height = _this.image.height;
        context = _this.canvas.getContext('2d');
        context.drawImage(_this.image, 0, 0);
        _this.pixels = context.getImageData(0, 0, _this.canvas.width, _this.canvas.height);
        _this.loaded = true;
        context = null;
        _this.canvas = null;
        _this.image = null;
        return callback != null ? callback.call(_this) : void 0;
      };
      this.image.crossOrigin = "anonymous";
      this.image.src = path;
    }

    /*
        Gets pixel RGBA data at given index
        
        @param x int In pixels
        @param y int In pixels
        @return Object{r,g,b,a}
    */


    ImageData.prototype.getPixel = function(x, y) {
      var i;
      if (!(this.pixels != null) || x < 0 || y < 0 || x >= this.pixels.width || y >= this.pixels.height) {
        return {
          r: 0,
          g: 0,
          b: 0,
          a: 0
        };
      }
      i = (y * this.pixels.width + x) * 4;
      return {
        r: this.pixels.data[i],
        g: this.pixels.data[i + 1],
        b: this.pixels.data[i + 2],
        a: this.pixels.data[i + 3]
      };
    };

    /*
        Gets pixel RGBA data at given float index using bilinear interpolation
        
        @param x float In subpixels
        @param y float In subpixels
        @return Object{r,g,b,a}
    */


    ImageData.prototype.getPixelBilinear = function(fx, fy) {
      var ax, ay, c, cf1, cf2, cx, cxy, cy, dx, dy, rx, ry, x, y;
      x = Math.floor(fx);
      y = Math.floor(fy);
      rx = fx - x - .5;
      ry = fy - y - .5;
      ax = Math.abs(rx);
      ay = Math.abs(ry);
      dx = rx < 0 ? -1 : 1;
      dy = ry < 0 ? -1 : 1;
      c = this.getPixel(x, y);
      cx = this.getPixel(x + dx, y);
      cy = this.getPixel(x, y + dy);
      cxy = this.getPixel(x + dx, y + dy);
      cf1 = [(1 - ax) * c.r + ax * cx.r, (1 - ax) * c.g + ax * cx.g, (1 - ax) * c.b + ax * cx.b, (1 - ax) * c.a + ax * cx.a];
      cf2 = [(1 - ax) * cy.r + ax * cxy.r, (1 - ax) * cy.g + ax * cxy.g, (1 - ax) * cy.b + ax * cxy.b, (1 - ax) * cy.a + ax * cxy.a];
      return {
        r: (1 - ay) * cf1[0] + ay * cf2[0],
        g: (1 - ay) * cf1[1] + ay * cf2[1],
        b: (1 - ay) * cf1[2] + ay * cf2[2],
        a: (1 - ay) * cf1[3] + ay * cf2[3]
      };
    };

    /*
        Gets pixel data at given index
        as 3-bytes integer (for floating-point textures erzats, from RGB values)
        
        @param x int In pixels
        @param y int In pixels
        @return int (R + G*255 + B*255*255)
    */


    ImageData.prototype.getPixelF = function(x, y) {
      var c;
      c = this.getPixel(x, y);
      return c.r + c.g * 255 + c.b * 255 * 255;
    };

    /*
        Gets pixel data at given float index using bilinear interpolationas
        as 3-bytes integer (for floating-point textures erzats, from RGB values)
        
        @param x float In subpixels
        @param y float In subpixels
        @return Object{r,g,b,a}
    */


    ImageData.prototype.getPixelFBilinear = function(fx, fy) {
      var c;
      c = this.getPixelBilinear(fx, fy);
      return c.r + c.g * 255 + c.b * 255 * 255;
    };

    return ImageData;

  })();

  /*
    Exports
    @package bkcore
  */


  exports = exports != null ? exports : this;

  exports.bkcore || (exports.bkcore = {});

  exports.bkcore.ImageData = ImageData;

}).call(this);