text: goog.provide('ol.source.ImageWMS');
  
  goog.require('goog.asserts');
  goog.require('goog.object');
  goog.require('ol.Image');
  goog.require('ol.ImageUrlFunction');
  goog.require('ol.extent');
  goog.require('ol.source.FeatureInfoSource');
  goog.require('ol.source.Image');
  goog.require('ol.source.wms');
  
  
  
  /**
   * @constructor
   * @extends {ol.source.Image}
   * @implements {ol.source.FeatureInfoSource}
   * @param {ol.source.ImageWMSOptions} options Options.
   */
  ol.source.ImageWMS = function(options) {
  
    /**
     * @private
     * @type {Object}
     */
    this.params_ = options.params;
  
    var imageUrlFunction = goog.isDef(options.url) ?
        ol.ImageUrlFunction.createFromParamsFunction(
            options.url, this.params_, ol.source.wms.getUrl) :
        ol.ImageUrlFunction.nullImageUrlFunction;
  
    goog.base(this, {
      attributions: options.attributions,
      crossOrigin: options.crossOrigin,
      extent: options.extent,
      projection: options.projection,
      resolutions: options.resolutions,
      imageUrlFunction: imageUrlFunction
    });
  
    /**
     * @private
     * @type {ol.source.WMSGetFeatureInfoOptions}
     */
    this.getFeatureInfoOptions_ = goog.isDef(options.getFeatureInfoOptions) ?
        options.getFeatureInfoOptions : {};
  
    /**
     * @private
     * @type {ol.Image}
     */
    this.image_ = null;
  
    /**
     * @private
     * @type {number}
     */
    this.ratio_ = goog.isDef(options.ratio) ?
        options.ratio : 1.5;
  
  };
  goog.inherits(ol.source.ImageWMS, ol.source.Image);
  
  
  /**
   * Get the user-provided params, i.e. those passed to the constructor through
   * the "params" option, and possibly updated using the updateParams method.
   * @return {Object} Params.
   */
  ol.source.ImageWMS.prototype.getParams = function() {
    return this.params_;
  };
  
  
  /**
   * @inheritDoc
   */
  ol.source.ImageWMS.prototype.getImage =
      function(extent, resolution, projection) {
    resolution = this.findNearestResolution(resolution);
  
    var image = this.image_;
    if (!goog.isNull(image) &&
        image.getResolution() == resolution &&
        ol.extent.containsExtent(image.getExtent(), extent)) {
      return image;
    }
  
    extent = extent.slice();
    ol.extent.scaleFromCenter(extent, this.ratio_);
    var width = (extent[2] - extent[0]) / resolution;
    var height = (extent[3] - extent[1]) / resolution;
    var size = [width, height];
  
    this.image_ = this.createImage(extent, resolution, size, projection);
    return this.image_;
  };
  
  
  /**
   * @inheritDoc
   */
  ol.source.ImageWMS.prototype.getFeatureInfoForPixel =
      function(pixel, map, success, opt_error) {
    var view2D = map.getView().getView2D(),
        projection = view2D.getProjection(),
        size = map.getSize(),
        bottomLeft = map.getCoordinateFromPixel([0, size[1]]),
        topRight = map.getCoordinateFromPixel([size[0], 0]),
        extent = [bottomLeft[0], topRight[0], bottomLeft[1], topRight[1]],
        url = this.imageUrlFunction(extent, size, projection);
    goog.asserts.assert(goog.isDef(url),
        'ol.source.ImageWMS#imageUrlFunction does not return a URL');
    ol.source.wms.getFeatureInfo(url, pixel, this.getFeatureInfoOptions_, success,
        opt_error);
  };
  
  
  /**
   * Update the user-provided params.
   * @param {Object} params Params.
   */
  ol.source.ImageWMS.prototype.updateParams = function(params) {
    goog.object.extend(this.params_, params);
    this.image_ = null;
    this.dispatchChangeEvent();
  };
  