Metacat

/*

Author:       Mike Adair mike.adairATccrs.nrcan.gc.ca

License: LGPL as per: http://www.gnu.org/copyleft/lesser.html

$Id$

*/

var Rearth = 6378137.0;                 // Radius of the earth (sphere); different from Proj value?

var degToMeter = Rearth*2*Math.PI/360;

//var mbScaleFactor = 72 * 39.3701;   //PixelsPerInch*InchesPerMapUnit; magic numbers 

                                    //need to determine magic number for lat/lon

var mbScaleFactor = 3571.428   //magic number, for Geoserver SLD compatibility

                               // 1/0.00028 (0.28 mm "is a common actual size for

                               // contemporary display" as written in the SLD specification ...

/*

 * FD 2005/03/04 : minScale et maxScale

 * DGR : should be in config ?

 */

var minScale = 1000;

var maxScale = 200000;

/**

 * A tool designed to handle geography calculations for widgets which render

 * the model in 2D.

 * Use of this tool requires that it's model implements get/setWindowHeight/Width

 * methods.

 * Encapsulates all geography and image size aspects of a geographic object 

 * displayed in a rectangular area on the screen.

 * All coordinates are handled as points which is a 2 element array, where x is 

 * the first element and y is the second. Coordinates are either pixel and lixel

 * (pl) relative to the top left of the extent or projection XY values (xy). 

 *

 * @constructor

 * @param model       the model document that this extent represents

 * @param initialRes  (optional) if supplied the extent resolution will be set to this value

 */

function Extent( model, initialRes ) {

  this.model = model;

  this.size = new Array();

  this.res = new Array();

  this.zoomBy = 4;

  this.id = model.id + "_MbExtent" + mbIds.getId();

  /**

   * Returns the XY center of this extent

   * @return  array of XY for th center of the extent

   */

  this.getCenter = function() {

    return new Array((this.ul[0]+this.lr[0])/2, (this.ul[1]+this.lr[1])/2);

  }

  /**

   * Returns XY coordinates for given pixel line coords w.r.t. top left corner

   * @param pl   pixel line in extent to calculate

   * @return     point array of XY coordinates

   */

  this.getXY = function(pl) {

    var x = this.ul[0]+pl[0]*this.res[0];

    var y = this.ul[1]- pl[1]*this.res[1];

    return new Array(x,y);

  }

  /**

   * Returns pixel/line coordinates for given XY projection coords

   * @param xy   projection XY coordinate to calculate

   * @return     point array of pxiel/line coordinates w.r.t. top left corner

   */

  this.getPL = function(xy) {

    var p = Math.floor( (xy[0]-this.ul[0])/this.res[0] );

    var l = Math.floor( (this.ul[1]-xy[1])/this.res[1] );

    return new Array(p,l);

  }

  /**

   * Adjust the extent so that it is centered at given XY coordinate with given

   * resolution.  Extent width and height remain fixed.  Optionally check to 

   * ensure that it doesn't go beyond available extent.

   *

   * @param center      projection XY coordinate to center at

   * @param newres      resolution to display at

   * @param limitExtent ensure that the extent doesn't go beyond available bbox (TBD: not complete/tested)

   * @return            none

   */

  this.centerAt = function(center, newres, limitExtent) {

    var half = new Array(this.size[0]/2, this.size[1]/2);

/*

 * FD 2005/03/04 : respect de minScale et maxScale

 * DGR : scale constraints

    var nRmin= minScale/mbScaleFactor;

    var nRmax= maxScale/mbScaleFactor;

    if (newres < nRmin) {

      newres= nRmin ;

    }

    if (newres > nRmax) {

      newres= nRmax ;

    }

 */

    this.lr = new Array(center[0]+half[0]*newres, center[1]-half[1]*newres);

    this.ul = new Array(center[0]-half[0]*newres, center[1]+half[1]*newres);

    //make sure the request doesn't extend beyond the available model

    //TBD this block not tested

    if ( limitExtent ) {

      var xShift = 0;

      if ( this.lr[0] > ContextExtent.lr[0] ) xShift = ContextExtent.lr[0] - this.lr[0];

      if ( this.ul[0] < ContextExtent.ul[0] ) xShift = ContextExtent.ul[0] - this.ul[0];

      this.lr[0] += xShift;

      this.ul[0] += xShift;

      var yShift = 0;

      if ( this.lr[1] < ContextExtent.lr[1] ) yShift = ContextExtent.lr[1] - this.lr[1];

      if ( this.ul[1] > ContextExtent.ul[1] ) yShift = ContextExtent.ul[1] - this.ul[1];

      this.lr[1] += yShift;

      this.ul[1] += yShift;

    }

    this.model.setBoundingBox( new Array(this.ul[0], this.lr[1], this.lr[0], this.ul[1]) );

    //this.setResolution(size);

    this.setSize(newres);

  }

  /**

   * Adjust the extent to the given bbox.  Resolution is recalculated. 

   * Extent width and height remain fixed.  

   * @param ul      upper left coordinate of bbox in XY projection coords

   * @param lr      lower right coordinate of bbox in XY projection coords

   */

  this.zoomToBox = function(ul, lr) {    //pass in xy

    var center = new Array((ul[0]+lr[0])/2, (ul[1]+lr[1])/2);

    newres = Math.max((lr[0] - ul[0])/this.size[0], (ul[1] - lr[1])/this.size[1]);

    this.centerAt( center, newres );

  } 

/**

   * Adjust the width and height to that bbox is displayed at specified resolution

   * @param res   the resolution to be set

   */

  //TBD update the model doc

  this.setSize = function(res) {     //pass in a resolution and width, height are recalculated

    this.res[0] = this.res[1] = res;

    this.size[0] = (this.lr[0] - this.ul[0])/this.res[0];

    this.size[1] = (this.ul[1] - this.lr[1])/this.res[1];

    this.width = Math.ceil(this.size[0]);

    this.height = Math.ceil(this.size[1]);

  }

  /**

   * Adjust the resolution so the bbox fits in the specified width and height

   * @param size   width, height array passed in

   */

  //TBD update the model doc

  this.setResolution = function(size) {    //pass in a width, height and res is recalculated

    this.size[0] = size[0];

    this.size[1] = size[1];

    this.res[0] = (this.lr[0] - this.ul[0])/this.size[0];

    this.res[1] = (this.ul[1] - this.lr[1])/this.size[1];

    this.width = Math.ceil(this.size[0]);

    this.height = Math.ceil(this.size[1]);

  }

  /**

   * Returns the map scale denominator for the current extent resolution

   * @return map scale denominator

   */

  this.getScale = function() {

    var pixRes = null;

    switch(this.model.getSRS()) {

      case "EPSG:4326":				//all projection codes in degrees

      case "EPSG:4269":				

        pixRes = this.res[0]*degToMeter;

        break;

      default:                //all projection codes in meters

        pixRes = this.res[0];

        break;

    }

    return mbScaleFactor*pixRes;

  }

  /**

   * Sets the model's resolution from mapScale input value.  The map center 

   * remains fixed.

   * @param scale   map scale denominator value

   */

  this.setScale = function(scale) {

    var newRes = null;

/*

 * FD 2005/03/04

 * On contraint l'echelle min et max de l'application.

 * A externaliser dans le fichier de config de l'application ;-)

 * DGR : should be in the config

    if (scale < minScale) {

      scale= minScale ;

    }

    if (scale > maxScale) {

      scale= maxScale ;

    }

 */

    switch(this.model.getSRS()) {

      case "EPSG:4326":				//all projection codes in degrees

      case "EPSG:4269":				

        //convert to resolution in degrees

        newRes = scale/(mbScaleFactor*degToMeter);

        break;

      default:                //all projection codes in meters

        newRes = scale/mbScaleFactor;

        break;

    }

    this.centerAt(this.getCenter(), newRes );

  }

  /**

   * Initialization of the Extent tool, called as a loadModel event listener.

   * @param extent      the object being initialized

   * @param initialRes  (optional) if supplied the extent resolution will be set to this value

   */

  this.init = function(extent, initialRes) {

    var bbox = extent.model.getBoundingBox();

    extent.ul = new Array(bbox[0],bbox[3]);

    extent.lr = new Array(bbox[2],bbox[1]);

/*

TBD: when called as a listener this gets a bbox array passed in, not initialRes value

    if ( initialRes ) {

      extent.setSize( initialRes );

    } else {

      extent.setResolution( new Array(extent.model.getWindowWidth(), extent.model.getWindowHeight() ) );

    }

*/

    extent.setResolution( new Array(extent.model.getWindowWidth(), extent.model.getWindowHeight() ) );

  }

  if ( initialRes ) this.init(this, initialRes);

  this.firstInit = function(extent, initialRes) {

  	extent.init(extent, initialRes);

    //TBD: this causes 2 paint() calls on initial load, not sure why it's here - MA

	  //extent.zoomToBox(extent.ul,extent.lr);

  }

}