Question

I would appreciate any help concerning pan and zoom for a jquery mobile web app. I have an image of a building floorplan with an image map on top that I would like the user to be able to view from his mobile phone, zoom in and out and pan the area of interest into view.

Answer 1

I figured it out, got everything I needed from the OpenLayers examples

<script type="text/javascript">
        var map;

        function init(){
            map = new OpenLayers.Map('map');
            var options = {numZoomLevels: 3}
            var floorplan = new OpenLayers.Layer.Image(
            'Floorplan Map',
            '../../temp_photos/sample-floor-plan.jpg',
            new OpenLayers.Bounds(-180, -90, 180, 90),
        new OpenLayers.Size(275, 190),
            options
        );
            map.addLayer(floorplan);
            //Create a Format object
            var vector_format = new OpenLayers.Format.GeoJSON({}); 

            //Create a Protocol object using the format object just created
            var vector_protocol = new OpenLayers.Protocol.HTTP({
                url: '../../controller?action=GET_FLOOR_FEATURES',               
                format: vector_format
            });

            //Create an array of strategy objects
            var vector_strategies = [new OpenLayers.Strategy.Fixed()];

            //Create a vector layer that contains a Format, Protocol, and Strategy class
            var vector_layer = new OpenLayers.Layer.Vector('More Advanced Vector Layer',{
                protocol: vector_protocol,
                strategies: vector_strategies 
            });

            map.addLayer(vector_layer);
               //Create and add selectFeature control
            var select_feature_control = new OpenLayers.Control.SelectFeature(
            vector_layer, 
            {
                multiple: false,
                toggle: true,
                toggleKey: 'ctrlKey',
                multipleKey: 'shiftKey' 
            }
        );
            map.addControl(select_feature_control); 

            //Activate the control
            select_feature_control.activate();

            //Finally, let's add some events so we can do stuff when the user 
            //  interacts with the features
            function selected_feature(event){
                //clear out the log's contents
                document.getElementById('map_feature_log').innerHTML = '';

                //Show the current selected feature (passed in from the event object)
                var display_text = 'Clicked on: ' 
                    + '<strong>' + event.feature.attributes.location + '</strong>'
                    + ': ' + event.feature.attributes.description + '<hr />';
                document.getElementById('map_feature_log').innerHTML = display_text;

                //Show all the selected features
                document.getElementById('map_feature_log').innerHTML += 'All selected features: ';

                //Now, loop through the selected feature array 
                for(var i=0; i<vector_layer.selectedFeatures.length; i++){
                    document.getElementById('map_feature_log').innerHTML += 
                        vector_layer.selectedFeatures[i].attributes.location + ' | ';
                }
            }
            function unselected_feature(event){
                var display_text = event.feature.attributes.location + ' unselected!' + '<hr />';
                document.getElementById('map_feature_log').innerHTML = display_text;

                //Show all the selected features
                document.getElementById('map_feature_log').innerHTML += 'All selected features: ';

                //Now, loop through the selected feature array 
                for(var i=0; i<vector_layer.selectedFeatures.length; i++){
                    document.getElementById('map_feature_log').innerHTML += 
                        vector_layer.selectedFeatures[i].attributes.location + ' | ';
                }
            }

            //Register the event
            vector_layer.events.register('featureselected', this, selected_feature);
            vector_layer.events.register('featureunselected', this, unselected_feature);

           if(!map.getCenter()){
                 map.setCenter(new OpenLayers.LonLat(0, 0),1);
            }
        }
    </script>

Markup:

Image Layer Example

    <p id="shortdesc">
        This is a floor plan for the first floor of the Science Building
    </p>

    <div id="map" class="smallmap"></div>

    <div id="docs"><div id='map_feature_log'></div>
        <p class="caption">
            This test shows how to display an image of a floorplan as a 
            base layer and then draw vectors on top of that, on a new layerage
        </p>
        <p>
            When vector is added popup appears with that vector's information
        </p>
    </div>
</body>

I get my features from the server:

package actions;

import control_layer.Action;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

/**
*
* @author christina
*/
public class GetFloorFeatures implements Action {

private static final int MAX_INACTIVE_INTERVAL = 900; // 15 minutes
private String view;

@Override
public boolean execute(HttpServletRequest req, HttpServletResponse res) throws ServletException, IOException {
    HttpSession session = req.getSession(true);
    System.out.println("------------ In GetFloorFeatures");
    session.setMaxInactiveInterval(MAX_INACTIVE_INTERVAL);

    view = "pages/maps/displayFloorFeatures.jsp";
    return true;
}

@Override
public String getView() {
    return view;
}

@Override
public Object getModel() {
    return null;
}

}

The data is hardcoded in the jsp file but it will eventually be generated by a database query:

<%@page contentType="application/json" pageEncoding="UTF-8"%>
<% response.setContentType("application/json");
//harcoded now, later will call database query to retrieve features for this floor
String floorFeatureVectors = "{\"type\": \"FeatureCollection\",\"features\":     [{\"type\":\"Feature\", \"id\":\"OpenLayers.Feature.Vector_84\",        \"properties\":{\"location\": \"Telecom Lab\",\"description\": \"Stand back, I'm going to try science!\"}, \"geometry\":{\"type\":\"Polygon\", \"coordinates\":[[[9, -52.342105263158], [9.4736842105263, -79.815789473684], [40.263157894737, -78.868421052632], [43.105263157895, -78.394736842105], [44.526315789474, -51.394736842105], [9, -52.342105263158]]]}, \"crs\":{\"type\":\"OGC\", \"properties\":{\"urn\":\"urn:ogc:def:crs:OGC:1.3:CRS84\"}}},"
    +   "{\"type\":\"Feature\", \"id\":\"OpenLayers.Feature.Vector_85\", \"properties\":{\"location\": \"MUSIC lab\",\"description\": \"Laboratory of Distributed Multimedia Information Systems and Applications \"}, \"geometry\":{\"type\":\"Polygon\", \"coordinates\":[[[-113.21052631579, 4.9736842105263], [-113.68421052632, -11.605263157895], [-76.263157894737, -13.026315789474], [-76.263157894737, -1.1842105263158], [-93.315789473684, -0.71052631578947], [-93.789473684211, 4.0263157894737], [-113.21052631579, 4.9736842105263]]]}, \"crs\":{\"type\":\"OGC\", \"properties\":{\"urn\":\"urn:ogc:def:crs:OGC:1.3:CRS84\"}}},"
    +   "{\"type\":\"Feature\", \"id\":\"OpenLayers.Feature.Vector_86\", \"properties\":{\"location\": \"Main Entrance Science Building\",\"description\": \"Caffeteria \"}, \"geometry\":{\"type\":\"Point\", \"coordinates\":[-8.0526315789474, 36.710526315789]}, \"crs\":{\"type\":\"OGC\", \"properties\":{\"urn\":\"urn:ogc:def:crs:OGC:1.3:CRS84\"}}}"

    + "]}";%><%=floorFeatureVectors%>