@cquiroz/aladin-lite/lib/js/CooGrid.js

AladinLite module

// Copyright 2015 - UDS/CNRS
// The Aladin Lite program is distributed under the terms
// of the GNU General Public License version 3.
//
// This file is part of Aladin Lite.
//
//    Aladin Lite is free software: you can redistribute it and/or modify
//    it under the terms of the GNU General Public License as published by
//    the Free Software Foundation, version 3 of the License.
//
//    Aladin Lite is distributed in the hope that it will be useful,
//    but WITHOUT ANY WARRANTY; without even the implied warranty of
//    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
//    GNU General Public License for more details.
//
//    The GNU General Public License is available in COPYING file
//    along with Aladin Lite.
//

/******************************************************************************
 * Aladin Lite project
 *
 * File CooGrid
 *
 * Author: Thomas Boch[CDS]
 *
 *****************************************************************************/
import AladinUtils from './AladinUtils';
import CooFrameEnum from './CooFrameEnum';

var CooGrid = function () {
  var CooGrid = function CooGrid() {};

  function viewxy2lonlat(projection, vx, vy, width, height, largestDim, zoomFactor) {
    var xy = AladinUtils.viewToXy(vx, vy, width, height, largestDim, zoomFactor);
    var lonlat;

    try {
      lonlat = projection.unproject(xy.x, xy.y);
    } catch (err) {
      return null;
    }

    return {
      lon: lonlat.ra,
      lat: lonlat.dec
    };
  }

  CooGrid.prototype.redraw = function (ctx, projection, frame, width, height, largestDim, zoomFactor, fov) {
    if (fov > 60) {
      // currently not supported
      return;
    }

    var lonMax = 0,
        lonMin = 359.9999,
        latMax = -90,
        latMin = 90;
    var lonlat1 = viewxy2lonlat(projection, 0, 0, width, height, largestDim, zoomFactor);
    var lonlat2 = viewxy2lonlat(projection, width - 1, height - 1, width, height, largestDim, zoomFactor);
    lonMin = Math.min(lonlat1.lon, lonlat2.lon);
    lonMax = Math.max(lonlat1.lon, lonlat2.lon);
    latMin = Math.min(lonlat1.lat, lonlat2.lat);
    latMax = Math.max(lonlat1.lat, lonlat2.lat);
    var lonlat3 = viewxy2lonlat(projection, 0, height - 1, width, height, largestDim, zoomFactor);
    lonMin = Math.min(lonMin, lonlat3.lon);
    lonMax = Math.max(lonMax, lonlat3.lon);
    latMin = Math.min(latMin, lonlat3.lat);
    latMax = Math.max(latMax, lonlat3.lat);
    var lonlat4 = viewxy2lonlat(projection, width - 1, 0, width, height, largestDim, zoomFactor);
    lonMin = Math.min(lonMin, lonlat4.lon);
    lonMax = Math.max(lonMax, lonlat4.lon);
    latMin = Math.min(latMin, lonlat4.lat);
    latMax = Math.max(latMax, lonlat4.lat);
    var lonDiff = lonMax - lonMin;
    var latDiff = latMax - latMin;
    var LON_STEP, LAT_STEP;

    if (fov > 10) {
      LON_STEP = 4;
      LAT_STEP = 4;
    } else if (fov > 1) {
      LON_STEP = 1;
      LAT_STEP = 1;
    } else if (fov > 0.1) {
      LON_STEP = 0.1;
      LAT_STEP = 0.1;
    } else {
      LON_STEP = 0.01;
      LAT_STEP = 0.01;
    }

    var lonStart = Math.round(lonMin % LON_STEP) * LON_STEP;
    var latStart = Math.round(latMin % LAT_STEP) * LAT_STEP;
    ctx.lineWidth = 1;
    ctx.strokeStyle = "rgb(120,120,255)"; // draw iso-latitudes lines

    for (var lat = latStart; lat < latMax + LAT_STEP; lat += LAT_STEP) {
      ctx.beginPath();
      var vxy = void 0;
      vxy = AladinUtils.radecToViewXy(lonMin, lat, projection, CooFrameEnum.J2000, width, height, largestDim, zoomFactor);

      if (!vxy) {
        continue;
      }

      ctx.moveTo(vxy.vx, vxy.vy);
      var k = 0;

      for (var lon = lonMin; lon < lonMax + LON_STEP; lon += lonDiff / 10) {
        k++;
        vxy = AladinUtils.radecToViewXy(lon, lat, projection, CooFrameEnum.J2000, width, height, largestDim, zoomFactor);
        ctx.lineTo(vxy.vx, vxy.vy);

        if (k === 3) {
          ctx.strokeText(lat.toFixed(2), vxy.vx, vxy.vy - 2);
        }
      }

      ctx.stroke();
    }

    for (var _lon = lonStart; _lon < lonMax + LON_STEP; _lon += LON_STEP) {
      ctx.beginPath();

      var _vxy = void 0;

      _vxy = AladinUtils.radecToViewXy(_lon, latMin, projection, CooFrameEnum.J2000, width, height, largestDim, zoomFactor);

      if (!_vxy) {
        continue;
      }

      ctx.moveTo(_vxy.vx, _vxy.vy);
      var _k = 0;

      for (var _lat = latMin; _lat < latMax + LAT_STEP; _lat += latDiff / 10) {
        _k++;
        _vxy = AladinUtils.radecToViewXy(_lon, _lat, projection, CooFrameEnum.J2000, width, height, largestDim, zoomFactor);
        ctx.lineTo(_vxy.vx, _vxy.vy);

        if (_k === 3) {
          ctx.strokeText(_lon.toFixed(2), _vxy.vx, _vxy.vy - 2);
        }
      }

      ctx.stroke();
    }
  };

  return CooGrid;
}();

export default CooGrid;