delays.js

/*
 delays.js: render the IDW layer of current delays

 Copyright 2011 Matt Conway

 Licensed under the Apache License, Version 2.0 (the "License");
 you may not use this file except in compliance with the License.
 You may obtain a copy of the License at

 http://www.apache.org/licenses/LICENSE-2.0

 Unless required by applicable law or agreed to in writing, software
 distributed under the License is distributed on an "AS IS" BASIS,
 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 See the License for the specific language governing permissions and
 limitations under the License.

 Authors:
 Matt Conway: main code

 */


MAP_PROJ = 'EPSG:900913';
DB_PROJ = 'EPSG:4326';

// The maximum delay that will be displayed; all others will be truncated to
// this. Seconds.
SCALE_TOP = 10 * 60; // 10 mins
SCALE_BOT = -10 * 60; // -3 mins (i.e. 3 mins early)


function drawHeatmap() {
    $('#load').fadeIn();

    var oldLayer = heat;

    heat = new IDW.Layer();
    heat.attribution = '<br/>Route and arrival data provided by permission of ' +
        '<a target="_blank" href="http://www.trimet.org">TriMet.</a>'
    heat.colours = [0x0000ffff, 0x00aa00ff, 0xff0000ff];

    var maxDelay = 0;
    var minDelay = 0;

    // Yay! No XHR issues!
    $.ajax({
        method: 'GET',
        url: '/cgi-bin/delays.py',
        dataType: 'json',
        success: function (data) {
            var dataLen = data.length;

            for (var i = 0; i < dataLen; i++) {
                // Truncate the delays to the scale
                if (data[i].avg > SCALE_TOP) avg = SCALE_TOP;
                else if (data[i].avg < SCALE_BOT) avg = SCALE_BOT;
                else avg = data[i].avg;

                source = new IDW.Source(
                    new OpenLayers.LonLat(data[i].stop_lon,
                        data[i].stop_lat)
                        .transform(new OpenLayers.Projection(DB_PROJ),
                            map.getProjectionObject()),
                    avg)
                heat.addSource(source);

                // This still refers to the non-tructaed average
                if (data[i].avg > maxDelay) maxDelay = data[i].avg;
                if (data[i].avg < minDelay) minDelay = data[i].avg;
            }

            // Force the scale to stay the same, at the min and max.
            heat.minval = SCALE_BOT;
            heat.maxval = SCALE_TOP;

            heat.setOpacity(0.65);
            heat.pixelSize = 8;

            // lastly, erase the old layer and add the new
            if (oldLayer != null) {
                map.removeLayer(oldLayer);
            }
            map.addLayer(heat);

            var mins = Math.floor(maxDelay / 60);
            var secs = Math.round(maxDelay - (mins * 60));

            minDelay = Math.abs(minDelay);
            var minMins = Math.floor(minDelay / 60);
            var minSecs = Math.round(minDelay - (minMins * 60));


            $('#maxDelay').text(mins + 'm ' + secs + 's');
            $('#minDelay').text('-' + minMins + 'm ' + minSecs + 's');
            $('#load').fadeOut();
        }
    });
}


$(document).ready(function () {
    $('#map').width($(window).width() - 180);
    $('#map').height($(window).height() - 60);

    map = new OpenLayers.Map("map", {projection: MAP_PROJ});
    var tileServers =
        ["http://otile1.mqcdn.com/tiles/1.0.0/osm/${z}/${x}/${y}.png",
            "http://otile2.mqcdn.com/tiles/1.0.0/osm/${z}/${x}/${y}.png",
            "http://otile3.mqcdn.com/tiles/1.0.0/osm/${z}/${x}/${y}.png",
            "http://otile4.mqcdn.com/tiles/1.0.0/osm/${z}/${x}/${y}.png"];
    var osm = new OpenLayers.Layer.OSM('MapQuest OSM', tileServers);

    // Add the MapQuest attribution
    osm.attribution += '<br/>Tiles courtesy of <a href="http://www.mapquest.com/" target="_blank">MapQuest</a> <img src="http://developer.mapquest.com/content/osm/mq_logo.png">';

    map.addLayer(osm);
    map.setBaseLayer(osm);

    map.setCenter(new OpenLayers.LonLat(-122.69110870364, 45.521493655281)
        .transform(
            new OpenLayers.Projection(DB_PROJ),
            map.getProjectionObject()), 13);


    heat = null;
    drawHeatmap();

    setInterval(drawHeatmap, 30 * 1000);

});