text: /*global define*/
  define([
          '../Core/defaultValue',
          '../Core/defined',
          '../Core/defineProperties',
          '../Core/DeveloperError',
          '../Core/Event',
          './createPropertyDescriptor'
      ], function(
          defaultValue,
          defined,
          defineProperties,
          DeveloperError,
          Event,
          createPropertyDescriptor) {
      'use strict';
  
      /**
       * Describes a two dimensional label located at the position of the containing {@link Entity}.
       * <p>
       * <div align='center'>
       * <img src='images/Label.png' width='400' height='300' /><br />
       * Example labels
       * </div>
       * </p>
       *
       * @alias LabelGraphics
       * @constructor
       *
       * @param {Object} [options] Object with the following properties:
       * @param {Property} [options.text] A Property specifying the text. Explicit newlines '\n' are supported.
       * @param {Property} [options.font='10px sans-serif'] A Property specifying the CSS font.
       * @param {Property} [options.style=LabelStyle.FILL] A Property specifying the {@link LabelStyle}.
       * @param {Property} [options.fillColor=Color.WHITE] A Property specifying the fill {@link Color}.
       * @param {Property} [options.outlineColor=Color.BLACK] A Property specifying the outline {@link Color}.
       * @param {Property} [options.outlineWidth=1.0] A numeric Property specifying the outline width.
       * @param {Property} [options.show=true] A boolean Property specifying the visibility of the label.
       * @param {Property} [options.showBackground=false] A boolean Property specifying the visibility of the background behind the label.
       * @param {Property} [options.backgroundColor=new Color(0.165, 0.165, 0.165, 0.8)] A Property specifying the background {@link Color}.
       * @param {Property} [options.backgroundPadding=new Cartesian2(7, 5)] A {@link Cartesian2} Property specifying the horizontal and vertical background padding in pixels.
       * @param {Property} [options.scale=1.0] A numeric Property specifying the scale to apply to the text.
       * @param {Property} [options.horizontalOrigin=HorizontalOrigin.CENTER] A Property specifying the {@link HorizontalOrigin}.
       * @param {Property} [options.verticalOrigin=VerticalOrigin.CENTER] A Property specifying the {@link VerticalOrigin}.
       * @param {Property} [options.eyeOffset=Cartesian3.ZERO] A {@link Cartesian3} Property specifying the eye offset.
       * @param {Property} [options.pixelOffset=Cartesian2.ZERO] A {@link Cartesian2} Property specifying the pixel offset.
       * @param {Property} [options.translucencyByDistance] A {@link NearFarScalar} Property used to set translucency based on distance from the camera.
       * @param {Property} [options.pixelOffsetScaleByDistance] A {@link NearFarScalar} Property used to set pixelOffset based on distance from the camera.
       * @param {Property} [options.heightReference=HeightReference.NONE] A Property specifying what the height is relative to.
       * @param {Property} [options.distanceDisplayCondition] A Property specifying at what distance from the camera that this label will be displayed.
       *
       * @demo {@link http://cesiumjs.org/Cesium/Apps/Sandcastle/index.html?src=Labels.html|Cesium Sandcastle Labels Demo}
       */
      function LabelGraphics(options) {
          this._text = undefined;
          this._textSubscription = undefined;
          this._font = undefined;
          this._fontSubscription = undefined;
          this._style = undefined;
          this._styleSubscription = undefined;
          this._fillColor = undefined;
          this._fillColorSubscription = undefined;
          this._outlineColor = undefined;
          this._outlineColorSubscription = undefined;
          this._outlineWidth = undefined;
          this._outlineWidthSubscription = undefined;
          this._horizontalOrigin = undefined;
          this._horizontalOriginSubscription = undefined;
          this._verticalOrigin = undefined;
          this._verticalOriginSubscription = undefined;
          this._eyeOffset = undefined;
          this._eyeOffsetSubscription = undefined;
          this._heightReference = undefined;
          this._heightReferenceSubscription = undefined;
          this._pixelOffset = undefined;
          this._pixelOffsetSubscription = undefined;
          this._scale = undefined;
          this._scaleSubscription = undefined;
          this._show = undefined;
          this._showSubscription = undefined;
          this._showBackground = undefined;
          this._showBackgroundSubscription = undefined;
          this._backgroundColor = undefined;
          this._backgroundColorSubscription = undefined;
          this._backgroundPadding = undefined;
          this._backgroundPaddingSubscription = undefined;
          this._translucencyByDistance = undefined;
          this._translucencyByDistanceSubscription = undefined;
          this._pixelOffsetScaleByDistance = undefined;
          this._pixelOffsetScaleByDistanceSubscription = undefined;
          this._distanceDisplayCondition = undefined;
          this._distanceDisplayConditionSubscription = undefined;
          this._definitionChanged = new Event();
  
          this.merge(defaultValue(options, defaultValue.EMPTY_OBJECT));
      }
  
      defineProperties(LabelGraphics.prototype, {
          /**
           * Gets the event that is raised whenever a property or sub-property is changed or modified.
           * @memberof LabelGraphics.prototype
           *
           * @type {Event}
           * @readonly
           */
          definitionChanged : {
              get : function() {
                  return this._definitionChanged;
              }
          },
  
          /**
           * Gets or sets the string Property specifying the text of the label.
           * Explicit newlines '\n' are supported.
           * @memberof LabelGraphics.prototype
           * @type {Property}
           */
          text : createPropertyDescriptor('text'),
  
          /**
           * Gets or sets the string Property specifying the font in CSS syntax.
           * @memberof LabelGraphics.prototype
           * @type {Property}
           * @see {@link https://developer.mozilla.org/en-US/docs/Web/CSS/font|CSS font on MDN}
           */
          font : createPropertyDescriptor('font'),
  
          /**
           * Gets or sets the Property specifying the {@link LabelStyle}.
           * @memberof LabelGraphics.prototype
           * @type {Property}
           */
          style : createPropertyDescriptor('style'),
  
          /**
           * Gets or sets the Property specifying the fill {@link Color}.
           * @memberof LabelGraphics.prototype
           * @type {Property}
           */
          fillColor : createPropertyDescriptor('fillColor'),
  
          /**
           * Gets or sets the Property specifying the outline {@link Color}.
           * @memberof LabelGraphics.prototype
           * @type {Property}
           */
          outlineColor : createPropertyDescriptor('outlineColor'),
  
          /**
           * Gets or sets the numeric Property specifying the outline width.
           * @memberof LabelGraphics.prototype
           * @type {Property}
           */
          outlineWidth : createPropertyDescriptor('outlineWidth'),
  
          /**
           * Gets or sets the Property specifying the {@link HorizontalOrigin}.
           * @memberof LabelGraphics.prototype
           * @type {Property}
           */
          horizontalOrigin : createPropertyDescriptor('horizontalOrigin'),
  
          /**
           * Gets or sets the Property specifying the {@link VerticalOrigin}.
           * @memberof LabelGraphics.prototype
           * @type {Property}
           */
          verticalOrigin : createPropertyDescriptor('verticalOrigin'),
  
          /**
           * Gets or sets the {@link Cartesian3} Property specifying the label's offset in eye coordinates.
           * Eye coordinates is a left-handed coordinate system, where <code>x</code> points towards the viewer's
           * right, <code>y</code> points up, and <code>z</code> points into the screen.
           * <p>
           * An eye offset is commonly used to arrange multiple labels or objects at the same position, e.g., to
           * arrange a label above its corresponding 3D model.
           * </p>
           * Below, the label is positioned at the center of the Earth but an eye offset makes it always
           * appear on top of the Earth regardless of the viewer's or Earth's orientation.
           * <p>
           * <div align='center'>
           * <table border='0' cellpadding='5'><tr>
           * <td align='center'><img src='images/Billboard.setEyeOffset.one.png' width='250' height='188' /></td>
           * <td align='center'><img src='images/Billboard.setEyeOffset.two.png' width='250' height='188' /></td>
           * </tr></table>
           * <code>l.eyeOffset = new Cartesian3(0.0, 8000000.0, 0.0);</code><br /><br />
           * </div>
           * </p>
           * @memberof LabelGraphics.prototype
           * @type {Property}
           * @default Cartesian3.ZERO
           */
          eyeOffset : createPropertyDescriptor('eyeOffset'),
  
          /**
           * Gets or sets the Property specifying the {@link HeightReference}.
           * @memberof LabelGraphics.prototype
           * @type {Property}
           * @default HeightReference.NONE
           */
          heightReference : createPropertyDescriptor('heightReference'),
  
          /**
           * Gets or sets the {@link Cartesian2} Property specifying the label's pixel offset in screen space
           * from the origin of this label.  This is commonly used to align multiple labels and labels at
           * the same position, e.g., an image and text.  The screen space origin is the top, left corner of the
           * canvas; <code>x</code> increases from left to right, and <code>y</code> increases from top to bottom.
           * <p>
           * <div align='center'>
           * <table border='0' cellpadding='5'><tr>
           * <td align='center'><code>default</code><br/><img src='images/Label.setPixelOffset.default.png' width='250' height='188' /></td>
           * <td align='center'><code>l.pixeloffset = new Cartesian2(25, 75);</code><br/><img src='images/Label.setPixelOffset.x50y-25.png' width='250' height='188' /></td>
           * </tr></table>
           * The label's origin is indicated by the yellow point.
           * </div>
           * </p>
           * @memberof LabelGraphics.prototype
           * @type {Property}
           * @default Cartesian2.ZERO
           */
          pixelOffset : createPropertyDescriptor('pixelOffset'),
  
          /**
           * Gets or sets the numeric Property specifying the uniform scale to apply to the image.
           * A scale greater than <code>1.0</code> enlarges the label while a scale less than <code>1.0</code> shrinks it.
           * <p>
           * <div align='center'>
           * <img src='images/Label.setScale.png' width='400' height='300' /><br/>
           * From left to right in the above image, the scales are <code>0.5</code>, <code>1.0</code>,
           * and <code>2.0</code>.
           * </div>
           * </p>
           * @memberof LabelGraphics.prototype
           * @type {Property}
           * @default 1.0
           */
          scale : createPropertyDescriptor('scale'),
  
          /**
           * Gets or sets the boolean Property specifying the visibility of the label.
           * @memberof LabelGraphics.prototype
           * @type {Property}
           */
          show : createPropertyDescriptor('show'),
  
          /**
           * Gets or sets the boolean Property specifying the visibility of the background behind the label.
           * @memberof LabelGraphics.prototype
           * @type {Property}
           * @default false
           */
          showBackground : createPropertyDescriptor('showBackground'),
  
          /**
           * Gets or sets the Property specifying the background {@link Color}.
           * @memberof LabelGraphics.prototype
           * @type {Property}
           * @default new Color(0.165, 0.165, 0.165, 0.8)
           */
          backgroundColor : createPropertyDescriptor('backgroundColor'),
  
          /**
           * Gets or sets the {@link Cartesian2} Property specifying the label's horizontal and vertical
           * background padding in pixels.
           * @memberof LabelGraphics.prototype
           * @type {Property}
           * @default new Cartesian2(7, 5)
           */
          backgroundPadding : createPropertyDescriptor('backgroundPadding'),
  
          /**
           * Gets or sets {@link NearFarScalar} Property specifying the translucency of the label based on the distance from the camera.
           * A label's translucency will interpolate between the {@link NearFarScalar#nearValue} and
           * {@link NearFarScalar#farValue} while the camera distance falls within the upper and lower bounds
           * of the specified {@link NearFarScalar#near} and {@link NearFarScalar#far}.
           * Outside of these ranges the label's translucency remains clamped to the nearest bound.
           * @memberof LabelGraphics.prototype
           * @type {Property}
           */
          translucencyByDistance : createPropertyDescriptor('translucencyByDistance'),
  
          /**
           * Gets or sets {@link NearFarScalar} Property specifying the pixel offset of the label based on the distance from the camera.
           * A label's pixel offset will interpolate between the {@link NearFarScalar#nearValue} and
           * {@link NearFarScalar#farValue} while the camera distance falls within the upper and lower bounds
           * of the specified {@link NearFarScalar#near} and {@link NearFarScalar#far}.
           * Outside of these ranges the label's pixel offset remains clamped to the nearest bound.
           * @memberof LabelGraphics.prototype
           * @type {Property}
           */
          pixelOffsetScaleByDistance : createPropertyDescriptor('pixelOffsetScaleByDistance'),
  
          /**
           * Gets or sets the {@link DistanceDisplayCondition} Property specifying at what distance from the camera that this label will be displayed.
           * @memberof LabelGraphics.prototype
           * @type {Property}
           */
          distanceDisplayCondition : createPropertyDescriptor('distanceDisplayCondition')
      });
  
      /**
       * Duplicates this instance.
       *
       * @param {LabelGraphics} [result] The object onto which to store the result.
       * @returns {LabelGraphics} The modified result parameter or a new instance if one was not provided.
       */
      LabelGraphics.prototype.clone = function(result) {
          if (!defined(result)) {
              return new LabelGraphics(this);
          }
          result.text = this.text;
          result.font = this.font;
          result.show = this.show;
          result.style = this.style;
          result.fillColor = this.fillColor;
          result.outlineColor = this.outlineColor;
          result.outlineWidth = this.outlineWidth;
          result.showBackground = this.showBackground;
          result.backgroundColor = this.backgroundColor;
          result.backgroundPadding = this.backgroundPadding;
          result.scale = this.scale;
          result.horizontalOrigin = this.horizontalOrigin;
          result.verticalOrigin = this.verticalOrigin;
          result.eyeOffset = this.eyeOffset;
          result.heightReference = this.heightReference;
          result.pixelOffset = this.pixelOffset;
          result.translucencyByDistance = this.translucencyByDistance;
          result.pixelOffsetScaleByDistance = this.pixelOffsetScaleByDistance;
          result.distanceDisplayCondition = this.distanceDisplayCondition;
          return result;
      };
  
      /**
       * Assigns each unassigned property on this object to the value
       * of the same property on the provided source object.
       *
       * @param {LabelGraphics} source The object to be merged into this object.
       */
      LabelGraphics.prototype.merge = function(source) {
          //>>includeStart('debug', pragmas.debug);
          if (!defined(source)) {
              throw new DeveloperError('source is required.');
          }
          //>>includeEnd('debug');
  
          this.text = defaultValue(this.text, source.text);
          this.font = defaultValue(this.font, source.font);
          this.show = defaultValue(this.show, source.show);
          this.style = defaultValue(this.style, source.style);
          this.fillColor = defaultValue(this.fillColor, source.fillColor);
          this.outlineColor = defaultValue(this.outlineColor, source.outlineColor);
          this.outlineWidth = defaultValue(this.outlineWidth, source.outlineWidth);
          this.showBackground = defaultValue(this.showBackground, source.showBackground);
          this.backgroundColor = defaultValue(this.backgroundColor, source.backgroundColor);
          this.backgroundPadding = defaultValue(this.backgroundPadding, source.backgroundPadding);
          this.scale = defaultValue(this.scale, source.scale);
          this.horizontalOrigin = defaultValue(this.horizontalOrigin, source.horizontalOrigin);
          this.verticalOrigin = defaultValue(this.verticalOrigin, source.verticalOrigin);
          this.eyeOffset = defaultValue(this.eyeOffset, source.eyeOffset);
          this.heightReference = defaultValue(this.heightReference, source.heightReference);
          this.pixelOffset = defaultValue(this.pixelOffset, source.pixelOffset);
          this.translucencyByDistance = defaultValue(this._translucencyByDistance, source.translucencyByDistance);
          this.pixelOffsetScaleByDistance = defaultValue(this._pixelOffsetScaleByDistance, source.pixelOffsetScaleByDistance);
          this.distanceDisplayCondition = defaultValue(this.distanceDisplayCondition, source.distanceDisplayCondition);
      };
  
      return LabelGraphics;
  });
  