protofarbtastic.js

// Prototype port of Farbtastic 1.2


Element.addMethods({
  protofarbtastic: function(container, callback) {
    var container = $(container);
    return container._protofarbtastic || (container._protofarbtastic = new ProtoFarbtastic(container, callback));
  }
});


var ProtoFarbtastic = Class.create();
ProtoFarbtastic.prototype = {
  initialize: function (container, callback) {

    // Store farbtastic object
    var fb = this;
    
    // Insert markup
    $(container).innerHTML = '<div class="farbtastic"><div class="color"></div><div class="wheel"></div><div class="overlay"></div><div class="h-marker marker"></div><div class="sl-marker marker"></div></div>';
    var e = $A(container.select('.farbtastic'));
    fb.wheel = container.select('.wheel')[0];
    // Dimensions
    fb.radius = 84;
    fb.square = 100;
    fb.width = 194;

    // Fix background PNGs in IE6
    if (navigator.appVersion.match(/MSIE [0-6]\./)) {
      e.each(function (el) {
          if (el.style.backgroundImage != 'none') {
            var image = el.style.backgroundImage;
            image = el.style.backgroundImage.substring(5, image.length - 2);
            $(el).setStyle({
              backgroundImage: 'none',
              filter: "progid:DXImageTransform.Microsoft.AlphaImageLoader(enabled=true, sizingMethod=crop, src='" + image + "')"
            });
          }
        });
    }
    
    /**
     * Link to the given element(s) or callback.
     */
    fb.linkTo = function (callback) {
      // Unbind previous nodes
      if (typeof fb.callback == 'object') {
        Event.stopObserving(fb, 'keyup', fb.updateValue, false);
      }
      
      // Reset color
      fb.color = null;
      
      // Bind callback or elements
      if (typeof callback == 'function') {
        fb.callback = callback;
      }
      else if (typeof callback == 'object' || typeof callback == 'string') {
        fb.callback = $(callback);
        Event.observe(fb.callback, 'keyup', fb.updateValue, false);
        if (fb.callback.value) {
          fb.setColor(fb.callback.value);
        }
      }
      return this;
    }

    fb.updateValue = function (event) {
      if (this.value && this.value != fb.color) {
        // Force upper-case hex values...
        this.value = this.value.toUpperCase();
        
        if (this.value.indexOf('#') != 0)
          this.value = '#' + this.value;
        
        fb.setColor(this.value);
      }
      Event.stop(event);
    }
    
    /**
     * Change color with HTML syntax #123456
     */
    fb.setColor = function (color) {
      var unpack = fb.unpack(color);
      if (fb.color != color && unpack) {
        fb.color = color;
        fb.rgb = unpack;
        fb.hsl = fb.RGBToHSL(fb.rgb);
        fb.updateDisplay();
      }
      return this;
    }

    /**
     * Change color with HSL triplet [0..1, 0..1, 0..1]
     */
    fb.setHSL = function (hsl) {
      fb.hsl = hsl;
      fb.rgb = fb.HSLToRGB(hsl);
      fb.color = fb.pack(fb.rgb);
      fb.updateDisplay();
      return this;
    }

    /////////////////////////////////////////////////////

    /**
     * Retrieve the coordinates of the given event relative to the center
     * of the widget.
     */
    fb.widgetCoords = function (event) {
      var x, y;
      var el = event.target || event.srcElement;
      var reference = fb.wheel;

      if (typeof event.offsetX != 'undefined') {
        // Use offset coordinates and find common offsetParent
        var pos = { x: event.offsetX, y: event.offsetY };

        // Send the coordinates upwards through the offsetParent chain.
        var e = el;
        while (e) {
          e.mouseX = pos.x;
          e.mouseY = pos.y;
          pos.x += e.offsetLeft;
          pos.y += e.offsetTop;
          e = e.offsetParent;
        }

        // Look for the coordinates starting from the wheel widget.
        var e = reference;
        var offset = { x: 0, y: 0 }
        while (e) {
          if (typeof e.mouseX != 'undefined') {
            x = e.mouseX - offset.x;
            y = e.mouseY - offset.y;
            break;
          }
          offset.x += e.offsetLeft;
          offset.y += e.offsetTop;
          e = e.offsetParent;
        }

        // Reset stored coordinates
        e = el;
        while (e) {
          e.mouseX = undefined;
          e.mouseY = undefined;
          e = e.offsetParent;
        }
      }
      else {
        // Use absolute coordinates
        var pos = fb.absolutePosition(reference);
        x = (event.pageX || 0*(event.clientX + document.body.scrollLeft)) - pos.x;
        y = (event.pageY || 0*(event.clientY + document.body.scrollTop)) - pos.y;
      }
      
      Event.stop(event);
      
      // Subtract distance to middle
      return { x: x - fb.width / 2, y: y - fb.width / 2 };
    }

    /**
     * Mousedown handler
     */
    fb.mousedown = function (event) {
      // Capture mouse
      if (!document.dragging) {
        Event.observe(document, 'mousemove', fb.mousemove, false);
        Event.observe(document, 'mouseup',   fb.mouseup, false);
        document.dragging = true;
      }

      // Check which area is being dragged
      var pos = fb.widgetCoords(event);
      fb.circleDrag = Math.max(Math.abs(pos.x), Math.abs(pos.y)) * 2 > fb.square;

      // Process
      fb.mousemove(event);
      
      if (event) Event.stop(event);
      
      return false;
    }

    /**
     * Mousemove handler
     */
    fb.mousemove = function (event) {
      // Get coordinates relative to color picker center
      var pos = fb.widgetCoords(event);

      // Set new HSL parameters
      if (fb.circleDrag) {
        var hue = Math.atan2(pos.x, -pos.y) / 6.28;
        if (hue < 0) hue += 1;
        fb.setHSL([hue, fb.hsl[1], fb.hsl[2]]);
      }
      else {
        var sat = Math.max(0, Math.min(1, -(pos.x / fb.square) + .5));
        var lum = Math.max(0, Math.min(1, -(pos.y / fb.square) + .5));
        fb.setHSL([fb.hsl[0], sat, lum]);
      }

      Event.stop(event);
      return false;
    }

    /**
     * Mouseup handler
     */
    fb.mouseup = function () {
      // Uncapture mouse
      Event.stopObserving(document, 'mousemove', fb.mousemove, false);
      Event.stopObserving(document, 'mouseup',   fb.mouseup, false);
      document.dragging = false;
    }

    /**
     * Update the markers and styles
     */
    fb.updateDisplay = function () {
      // Markers
      var angle = fb.hsl[0] * 6.28;
      $A(e).each(function(itE) {
          $A(itE.select('.h-marker')).each(function(el) {
              el.setStyle({
                left: Math.round(Math.sin(angle) * fb.radius + fb.width / 2) + 'px',
                    top: Math.round(-Math.cos(angle) * fb.radius + fb.width / 2) + 'px'
                    });
            });
        });

      $A(e).each(function(itE) {
          $A(itE.select('.sl-marker')).each(function(el) {
              el.setStyle({
                left: Math.round(fb.square * (.5 - fb.hsl[1]) + fb.width / 2) + 'px',
                    top: Math.round(fb.square * (.5 - fb.hsl[2]) + fb.width / 2) + 'px'              
                    });
            });
        });
      
      // Saturation/Luminance gradient
      $A(e).each(function(itE) {
          $A(itE.select('.color')).each(function(el) {
              el.setStyle({
                backgroundColor: fb.pack(fb.HSLToRGB([fb.hsl[0], 1, 0.5]))
                    });
            });
        });
      
      // Linked elements or callback
      if (typeof fb.callback == 'object') {
        // Set background/foreground color

        $A([fb.callback]).flatten().each(function(el) {
            el.setStyle({
              backgroundColor: fb.color,
              color: fb.hsl[2] > 0.5 ? '#000' : '#fff'
            });
          });

        // Change linked value
        $A([fb.callback]).flatten().each(function(el) {
            if (el.value && el.value != fb.color) {
              el.value = fb.color;
            }
          });
      }
      else if (typeof fb.callback == 'function') {
        fb.callback.call(fb, fb.color);
      }
    }

    /**
     * Get absolute position of element
     */
    fb.absolutePosition = function (el) {
      var r = { x: el.offsetLeft, y: el.offsetTop };
      // Resolve relative to offsetParent
      if (el.offsetParent) {
        var tmp = fb.absolutePosition(el.offsetParent);
        r.x += tmp.x;
        r.y += tmp.y;
      }
      return r;
    };

    /* Various color utility functions */
    fb.pack = function (rgb) {
      var r = Math.round(rgb[0] * 255);
      var g = Math.round(rgb[1] * 255);
      var b = Math.round(rgb[2] * 255);
      return ('#' + (r < 16 ? '0' : '') + r.toString(16) +
                    (g < 16 ? '0' : '') + g.toString(16) +
                    (b < 16 ? '0' : '') + b.toString(16)).toUpperCase();
    }

    fb.unpack = function (color) {
      if (color.length == 7) {
        return [parseInt('0x' + color.substring(1, 3)) / 255,
                parseInt('0x' + color.substring(3, 5)) / 255,
                parseInt('0x' + color.substring(5, 7)) / 255];
      }
      else if (color.length == 4) {
        return [parseInt('0x' + color.substring(1, 2)) / 15,
                parseInt('0x' + color.substring(2, 3)) / 15,
                parseInt('0x' + color.substring(3, 4)) / 15];
      }
    }

    fb.HSLToRGB = function (hsl) {
      var m1, m2, r, g, b;
      var h = hsl[0], s = hsl[1], l = hsl[2];
      m2 = (l <= 0.5) ? l * (s + 1) : l + s - l*s;
      m1 = l * 2 - m2;
      return [this.hueToRGB(m1, m2, h+0.33333),
              this.hueToRGB(m1, m2, h),
              this.hueToRGB(m1, m2, h-0.33333)];
    }

    fb.hueToRGB = function (m1, m2, h) {
      h = (h < 0) ? h + 1 : ((h > 1) ? h - 1 : h);
      if (h * 6 < 1) return m1 + (m2 - m1) * h * 6;
      if (h * 2 < 1) return m2;
      if (h * 3 < 2) return m1 + (m2 - m1) * (0.66666 - h) * 6;
      return m1;
    }

    fb.RGBToHSL = function (rgb) {
      var min, max, delta, h, s, l;
      var r = rgb[0], g = rgb[1], b = rgb[2];
      min = Math.min(r, Math.min(g, b));
      max = Math.max(r, Math.max(g, b));
      delta = max - min;
      l = (min + max) / 2;
      s = 0;
      if (l > 0 && l < 1) {
        s = delta / (l < 0.5 ? (2 * l) : (2 - 2 * l));
      }
      h = 0;
      if (delta > 0) {
        if (max == r && max != g) h += (g - b) / delta;
        if (max == g && max != b) h += (2 + (b - r) / delta);
        if (max == b && max != r) h += (4 + (r - g) / delta);
        h /= 6;
      }
      return [h, s, l];
    }

    // Install mousedown handler (the others are set on the document on-demand)
    // $('*', e).mousedown(fb.mousedown);
    e.each(function (el) {
        Event.observe(el, 'mousedown', fb.mousedown, false);
      });
    // Init color
    fb.setColor('#000000');

    // Set linked elements/callback
    if (callback) {
      fb.linkTo(callback);
    }
  }
};