Extended Nomads Objects -- Google Maps Interface

From PxPlus

A new Extended Control has been added to PxPlus to allow you to access external features, such as the Google Maps API, in a Nomads or iNomads environment. PxPlus Extended Controls are available through the Nomads COM interface, allowing you to select from a list of PVX Controls in addition to the list of Activex Controls when selecting a COM Control Name in the Nomads Designer. The remainder of the Nomads definition and processing is identical to that of a COM control. However, unlike most other COM controls, extended controls are also supported by iNomads.

The first extended control to be added to PxPlus is a Google Maps interface using the Google Maps API V3. Google Maps is a web mapping service application and technology provided by Google Inc., so access to the internet is a requirement to use the service. The PxPlus Google Maps extended control offers access to a wide range of features available in the Google Maps API,including map-related properties, methods and events, marker and info window processing, as well as geocoder functions. A built-in link on all maps also gives the user access to the Google Maps web page and additional functionality, such as directions requests.

Nomads	iNomads

Please visit the Google web site to learn the terms and conditions for including maps, geocoding and other content from Google in your webpages or applications. http://code.google.com/apis/maps/terms.html

Also visit the Google web site for more information on the Google Maps API V3: http://code.google.com/apis/maps/documentation/v3/

Contact PVXPlus Technologies to inquire about incorporating additional functionality into the PxPlus Google Map extended control.

To see a Flash presentation on using the Google Map extended control, go to http://www.pvxplus.com/swf/gmaps.htm

Using the Google Map Extended Control

Use the Nomads Designer to add a Google Map to your application panel.

Select External Tools (COM control) from the Controls window and outline the location of the map on the panel.

In the Properties window, name the control; in our example we have called it MAP. Then click the COM Control Name button in the Display section and select PVX Controls from the pop-up menu. Select Google Maps Control from the list.

Click the Properties/Methods/Events button in the Display section of the Properties window.

Four properties are required when defining a map:

latitude - Latitude in degrees of the centerpoint of the map. Range is -90 to 90 degrees.
longitude - Longitude in degrees of the centerpoint of the map. Range wraps from -180 to 180 degrees.
mapTypeId - Type of map to be displayed. Options are hybrid, roadmap, satellite and terrain.
zoom - Numeric zoom factor for the map. (Zero based).

Other properties are optional. Save the definition. This is sufficient to display the map on your panel, complete with map type and zoom controls, and full standard Google Map UI capability, including full mouse and keyboard control.

Now add some controls and logic to demonstrate some of the functionality available in Google Maps, such as adding and removing markers and info windows, and a demonstration of geocoding which translates human-readable addresses into latitude/longitude locations and vice-versa.

Add three multilines, address, latitude and longitude, as well as fonted-text prompts to accompany them. Set the Numeric attribute for the latitude and longitude multilines.

You will need more than standard precision to handle latitude and longitude values, so set Precision to 6 in the Display section of the panel header Properties window.

Add a Geocode_Address button, a Geocode_Location button, and a Close button to exit the panel. Set the On Change logic for the Close button to End.

Set the On Change logic for the Geocode_Address button to Execute: location$=map.ctl'geocode$(address$); latitude=map.ctl'geocodeLatitude; longitude=map.ctl'geocodeLongitude; map.ctl'addMarker(latitude,longitude,location$) When the button is pushed, the address is passed to the geocode method which returns the latitude and longitude as a string with a comma separator. The geocoder also loads the geocodeLatitude and geocodeLongitude properties which are used here to populate the latitude and longitude multilines. A marker is then created using the given latitude and longitude, and the location is used as the marker title, which is displayed as the marker tip.
	Set the On Change logic for the Geocode_Location button to Execute: address$=map.ctl'geocode$(latitude,longitude,0); map.ctl'showInfoWindow(latitude,longitude,address$) When the button is pushed, the latitude, longitude and level are passed to the geocode method. The level indicates how specific or general the returned address is to be, with 0 being the most specific address. The address is then displayed in an info window placed at the given latitude and longitude.
Finally, click the Properties/Methods/Events button in the Display section of the Map Properties window. Set the markerClick event logic to Execute: markerid=map.ctl'clickmarker; map.ctl'removeMarker(markerid) When a marker is clicked, it is removed from the map.

This example shows just a few of the properties, methods and events available to the Google Maps Extended Control. Full details are described in the rest of this document. Also visit the Google Maps web site for additional information. http://code.google.com/apis/maps/documentation/v3/

Map Properties

Following are the map-related properties supported by the PxPlus Google Maps Extended Control. The properties are set when the map is created, and are read-only (except for the value property). Their values can be changed subsequently by using the corresponding set method.

Property	Description
backgroundColor$	Colour used for the background of the map. This colour is visible when tiles have not yet been loaded and the user pans. Format is hex #HHHHHH (e.g. #FF00FF) or a standard HTML colour name (e.g. yellow).
clickLatitude	Latitude in degrees at the location where a Click or RightClick event occurs on a map.
clickLongitude,	Longitude in degrees at the location where a Click or RightClick event occurs on a map.
clickMarker	Numeric identifier of the marker involved in a MarkerClick event.
col	Horizontal screen position of map in columns.
cols	Width of map in column units.
containerObject	Object id of browser object in which the map is displayed. (NOMADS only)
ctlName$	Control type. Value is 'Extended'.
disableDefaultUI	Enables/disables all default user interface features, such as double click zoom, draggability, scrollwheel, etc. UI features may be overridden individually. Boolean. Default is false (enabled).
draggable	Enables/disables the ability to drag the map. Boolean. Default is true (enabled).
geocodeLatitude	Longitude in degrees at the location of the last invoked #Geocoder Method.
geocodeLongitude	Longitude in degrees at the location of the last invoked #Geocoder Method.
geocodeStatus$	Status of the last invoked #Geocoder Method.
infoWindowCount	Number of info windows currently displayed.
keyboardShortcuts	Enables/disables keyboard control of the map. Boolean. Default is enabled (true).
latitude	Latitude in degrees of the map center. Range is clamped between -90 degrees and 90 degrees.
longitude	Longitude in degrees of the map center. Longitude is wrapped between -180 degrees and 180 degrees.
mapTypeControl	Enabled/disabled state of the map type control. Boolean. Default is enabled.
mapTypeControlStyle$	Display option for the map type control. Options are 'default', 'dropdown_menu' and 'horizontal_bar'.
mapTypeId$	Map type. Options are 'hybrid', 'roadmap', 'satellite' and 'terrain'. Required.
markerCount	Number of markers currently displayed.
name$	Control name.
navigationControl	Enabled/disabled state of the navigation control. Boolean. Default is enabled.
navigationControlStyle$	Display option for the navigation control. Options are 'default', 'android', 'small' and 'zoom_pan'. The default setting varies depending on map size and other factors.
noClear	If true, the contents of the map are not cleared.
pvxError$	Error value.
pvxEvents$	List of available events.
region$	Unicode region subtag identifier. Can be used to override the standard location bias. (Optional)
scaleControl	Enabled/disabled state of the scale control.
scaleControlStyle$	Display option for the scale control. Option is 'default'.
scrollWheel	Enables/disables scrollwheel zooming on the map. Boolean. Default is true (enabled).
sensor	Indicates whether the application is using a sensor (such as a GPS locator) to determine the location. Boolean. Default is false. Required.
value$	String of value pairs that contain all the data required to define the current map. Format is a list of assignment expressions separated by $00$. e.g. "sensor=0"+$00$+ "region$="""""+$00$+ "latitude=43.77"+$00$+ "longitude=-79.4525"+$00$+ "mapTypeID$=""hybrid""+$00$+ "zoom=14"+$00$+ [etc.] An example (not showing the $00$ separators) is shown on the right. The value$ property is a read/write property. When set, the map is redisplayed using the new value settings.
zoom	Initial zoom level for the map. Required.

Map Events

Following are the events supported by the PxPlus Google Maps Extended Control.

Map Methods

Following are the map-related methods supported by the PxPlus Google Maps Extended Control.

"mapTypeID=terrain"+SEP+"draggable=false"+SEP+"zoom=4"+sep+"backgroundColor="+SEP

Marker Methods

Following are the marker methods supported by the PxPlus Google Maps Extended Control.

setMarkerIcon(markerid,"file:///c:/work/images/star.bmp")
setMarkerIcon(markerid,"http://www.mydomain.com/home/images/mymarker.jpg")

"draggable=true"+SEP+"title="+SEP+"+"icon=file:///work/images/star.bmp"+SEP

Info Window Methods

An info window is a text bubble that can be displayed at a given location or connected to a marker. Following are the info window methods supported by the PxPlus Google Maps Extended Control.

Geocoder Method

Geocoding is the process of converting human-readable addresses (like "42 Scenic Drive, Yourtown, ON") into geographic coordinates (like latitude 44.123456 and longitude -79.654321), which you can use to place markers or position the map. The process of translating a location on a map to a human-readable address is known as reverse geocoding. Both processes are available using the two formats of the geocode$( ) method.