text: /**
   * @class Ext.chart.Label
   *
   * Labels is a mixin whose methods are appended onto the Series class. Labels is an interface with methods implemented
   * in each of the Series (Pie, Bar, etc) for label creation and label placement.
   *
   * The methods implemented by the Series are:
   *  
   * - **`onCreateLabel(storeItem, item, i, display)`** Called each time a new label is created.
   *   The arguments of the method are:
   *   - *`storeItem`* The element of the store that is related to the label sprite.
   *   - *`item`* The item related to the label sprite. An item is an object containing the position of the shape
   *     used to describe the visualization and also pointing to the actual shape (circle, rectangle, path, etc).
   *   - *`i`* The index of the element created (i.e the first created label, second created label, etc)
   *   - *`display`* The display type. May be <b>false</b> if the label is hidden
   *
   *  - **`onPlaceLabel(label, storeItem, item, i, display, animate)`** Called for updating the position of the label.
   *    The arguments of the method are:
   *    - *`label`* The sprite label.</li>
   *    - *`storeItem`* The element of the store that is related to the label sprite</li>
   *    - *`item`* The item related to the label sprite. An item is an object containing the position of the shape
   *      used to describe the visualization and also pointing to the actual shape (circle, rectangle, path, etc).
   *    - *`i`* The index of the element to be updated (i.e. whether it is the first, second, third from the labelGroup)
   *    - *`display`* The display type. May be <b>false</b> if the label is hidden.
   *    - *`animate`* A boolean value to set or unset animations for the labels.
   */
  Ext.define('Ext.chart.Label', {
  
      /* Begin Definitions */
  
      requires: ['Ext.draw.Color'],
      
      /* End Definitions */
  
      /**
       * @cfg {String} display
       * Specifies the presence and position of labels for each pie slice. Either "rotate", "middle", "insideStart",
       * "insideEnd", "outside", "over", "under", or "none" to prevent label rendering.
       * Default value: 'none'.
       */
  
      /**
       * @cfg {String} color
       * The color of the label text.
       * Default value: '#000' (black).
       */
  
      /**
       * @cfg {String} field
       * The name of the field to be displayed in the label.
       * Default value: 'name'.
       */
  
      /**
       * @cfg {Number} minMargin
       * Specifies the minimum distance from a label to the origin of the visualization.
       * This parameter is useful when using PieSeries width variable pie slice lengths.
       * Default value: 50.
       */
  
      /**
       * @cfg {String} font
       * The font used for the labels.
       * Defautl value: "11px Helvetica, sans-serif".
       */
  
      /**
       * @cfg {String} orientation
       * Either "horizontal" or "vertical".
       * Dafault value: "horizontal".
       */
  
      /**
       * @cfg {Function} renderer
       * Optional function for formatting the label into a displayable value.
       * Default value: function(v) { return v; }
       * @param v
       */
  
      //@private a regex to parse url type colors.
      colorStringRe: /url\s*\(\s*#([^\/)]+)\s*\)/,
      
      //@private the mixin constructor. Used internally by Series.
      constructor: function(config) {
          var me = this;
          me.label = Ext.applyIf(me.label || {},
          {
              display: "none",
              color: "#000",
              field: "name",
              minMargin: 50,
              font: "11px Helvetica, sans-serif",
              orientation: "horizontal",
              renderer: function(v) {
                  return v;
              }
          });
  
          if (me.label.display !== 'none') {
              me.labelsGroup = me.chart.surface.getGroup(me.seriesId + '-labels');
          }
      },
  
      //@private a method to render all labels in the labelGroup
      renderLabels: function() {
          var me = this,
              chart = me.chart,
              gradients = chart.gradients,
              gradient,
              items = me.items,
              animate = chart.animate,
              config = me.label,
              display = config.display,
              color = config.color,
              field = [].concat(config.field),
              group = me.labelsGroup,
              store = me.chart.store,
              len = store.getCount(),
              ratio = items.length / len,
              i, count, index, j, 
              k, gradientsCount = (gradients || 0) && gradients.length,
              colorStopTotal, colorStopIndex, colorStop,
              item, label, storeItem,
              sprite, spriteColor, spriteBrightness, labelColor,
              Color = Ext.draw.Color,
              colorString;
  
          if (display == 'none') {
              return;
          }
  
          for (i = 0, count = 0; i < len; i++) {
              index = 0;
              for (j = 0; j < ratio; j++) {
                  item = items[count];
                  label = group.getAt(count);
                  storeItem = store.getAt(i);
                  
                  //check the excludes
                  while(this.__excludes && this.__excludes[index]) {
                      index++;
                  }
  
                  if (!item && label) {
                      label.hide(true);
                  }
  
                  if (item && field[j]) {
                      if (!label) {
                          label = me.onCreateLabel(storeItem, item, i, display, j, index);
                      }
                      me.onPlaceLabel(label, storeItem, item, i, display, animate, j, index);
  
                      //set contrast
                      if (config.contrast && item.sprite) {
                          sprite = item.sprite;
                          colorString = sprite._to && sprite._to.fill || sprite.attr.fill;
                          spriteColor = Color.fromString(colorString);
                          //color wasn't parsed property maybe because it's a gradient id
                          if (colorString && !spriteColor) {
                              colorString = colorString.match(me.colorStringRe)[1];
                              for (k = 0; k < gradientsCount; k++) {
                                  gradient = gradients[k];
                                  if (gradient.id == colorString) {
                                      //avg color stops
                                      colorStop = 0; colorStopTotal = 0;
                                      for (colorStopIndex in gradient.stops) {
                                          colorStop++;
                                          colorStopTotal += Color.fromString(gradient.stops[colorStopIndex].color).getGrayscale();
                                      }
                                      spriteBrightness = (colorStopTotal / colorStop) / 255;
                                      break;
                                  }
                              }
                          }
                          else {
                              spriteBrightness = spriteColor.getGrayscale() / 255;
                          }
                          labelColor = Color.fromString(label.attr.color || label.attr.fill).getHSL();
                          
                          labelColor[2] = spriteBrightness > 0.5? 0.2 : 0.8;
                          label.setAttributes({
                              fill: String(Color.fromHSL.apply({}, labelColor))
                          }, true);
                      }
                  }
                  count++;
                  index++;
              }
          }
          me.hideLabels(count);
      },
  
      //@private a method to hide labels.
      hideLabels: function(index) {
          var labelsGroup = this.labelsGroup, len;
          if (labelsGroup) {
              len = labelsGroup.getCount();
              while (len-->index) {
                  labelsGroup.getAt(len).hide(true);
              }
          }
      }
  });