updated Threshold filter and test

src/filters/Threshold.js

@@ -4,58 +4,31 @@
    * Threshold Filter. Pushes any value above the mid point to 
    *  the max and any value below the mid point to the min.
    *  This affects the alpha channel.
-   *  Performs w*h pixel reads and w*h pixel writes.
    * @function
-   * @author ippo615
    * @memberof Kinetic.Filters
-   * @param {ImageData} src, the source image data (what will be transformed)
-   * @param {ImageData} dst, the destination image data (where it will be saved)
-   * @param {Object} opt
-   * @param {Number} [opt.thresholdLevel=128] the value which divides
-   *  the channel value into 2 groups (between 0 and 255)
+   * @param {Object} imageData
+   * @author ippo615
    */
 
-  var Threshold = function (src, dst, opt) {
-    var level = 128;
-    if( opt.hasOwnProperty ){
-      level = opt.thresholdLevel;
-    }
-    var srcPixels = src.data,
-      dstPixels = dst.data,
-      nPixels = srcPixels.length,
-      i;
-    for (i = 0; i < nPixels; i += 1) {
-      if (srcPixels[i] < level) {
-        dstPixels[i] = 0;
-      } else {
-        dstPixels[i] = 255;
-      }
+  Kinetic.Filters.Threshold = function (imageData) {
+    var level = this.threshold() * 255,
+        data = imageData.data,
+        len = data.length,
+        i;
+
+    for (i = 0; i < len; i += 1) {
+      data[i] = data[i] < level ? 0 : 255;
     }
   };
 
-  Kinetic.Factory.addFilterGetterSetter(Kinetic.Node, 'threshold', 128);
+  Kinetic.Factory.addFilterGetterSetter(Kinetic.Node, 'threshold', 0.5);
 
-  Kinetic.Filters.Threshold = function(src,dst,opt){
-    if( this === Kinetic.Filters ){
-      Threshold(src, dst||src, opt );
-    }else{
-      Threshold.call(this, src, dst||src, opt || {
-        thresholdLevel: this.getThresholdLevel()
-      });
-    }
-  };
-
-    /**
-    * get threshold level.  Returns the level which divides the color channel (0-255).
-    * @name getThresholdLevel
-    * @method
-    * @memberof Kinetic.Image.prototype
-    */
-
-    /**
-    * set threshold level.  Sets the level which divides the color channel (0-255).
-    * @name setThresholdLevel
-    * @method
-    * @memberof Kinetic.Image.prototype
-    */
+  /**
+  * get/set threshold.  Value between 0 and 1
+  * @name threshold
+  * @method
+  * @memberof Kinetic.Image.prototype
+  * @param {Number} threshold
+  * @returns {Number}
+  */
 })();