Difference between revisions of "Linden Lab Official:Map API Advanced Examples"

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=== Setting a onStateChangedHandler event handler ===
=== Setting a onStateChangedHandler event handler ===


The map object has an onStateChangedHandler that is a function called whenever the user pans or zooms the map.  Specify it in the [[Webmap_API_Reference#SLMapOptions|options]] when you initially create the map object.  For example:
The map object has an onStateChangedHandler option that is a function called whenever the user pans or zooms the map.  Specify it in the [[Webmap_API_Reference#SLMapOptions|options]] when you initially create the map object.  For example:


<pre>
<pre>

Revision as of 15:16, 30 January 2009

Update notice

We've made improvements and changes to the webmap, effective January 15, 2009.
Some information here may be out of date as we update this wiki with the changes. Thanks for your patience.


Linking to a Second Life coordinate using x and y coordinates (NEW)

Teleport window.png

The new gotoSLURL() global function enables the user to teleport to the specified coordinate, given a valid SLMap instance. It first opens a window displaying the region name and a "Teleport" button, for example as shown at right.



For example, the following method call will pop-up the window illustrated here; the user can the click the "Teleport" button to open the Second Life Viewer and teleport to (997,1002). 

gotoSLURL(997,1002, mapInstance);

The example code below provides several similar examples.

Source code 

<!-- Insert HTML header here -->
<script>
var mapInstance;
function loadmap() {
  // creates the map
  mapInstance = new SLMap(document.getElementById('map-container'));
  mapInstance.centerAndZoomAtSLCoord(new XYPoint(997, 1002), 2);
}
</script>
</head>
<body onload="loadmap()" onunload="GUnload()">
<div id="map-container"></div>
<p>Click on these links to be teleported into Second Life via a SLURL:
<p><a href="javascript:gotoSLURL(997, 1002, mapInstance)"> Go to (997, 1002) </a>(where the welcome fountain is) <br />
<a href="javascript:gotoSLURL(996.5, 1001.6, mapInstance)"> Go to (996.5, 1001.6) </a> <br />

<a href="javascript:gotoSLURL(1000, 1000, mapInstance)"> Go to (1000, 1000) </a><br />
</body>

Working with maps

The SLMap object provides a great deal of control over how you display and interact with the map. You can:

  • Customize the zoom and pan controls.
  • Disable and enable dragging the map.
  • Pan/re-center the map to a specified location.
  • Define event handler functions, called when:
    • The user zooms or pans the map.
    • The user clicks on the map.
    • The user double-clicks on the map.
  • Get the cooridnates of the map's center and bounds.

Customizing zoom and pan controls

It's easy to remove all the zoom and pan controls or create your own. When you create the SLMap object, simply specify false for the SLMapOptions properties hasZoomControls and hasPanningControls, for example: 

mapInstance = new SLMap(document.getElementById('map-container'), 
                        {hasZoomControls: false, 
                         hasPanningControls: false});

This code creates a map with no zoom and pan controls.

To create your own zoom controls use the SLMap methods:

  • setCurrentZoomLevel()
  • getCurrentZoomLevel()
  • zoomIn()
  • zoomOut()

To create your own panning controls, use the SLMap methods:

  • panLeft()
  • panRight()
  • panUp()
  • panDown()

The following example contains a set of anchored links that call a function when clicked.

Example source code 

<!-- Insert common HTML header -->
<script>
var mapInstance;

function loadmap() {
  // creates the map
  mapInstance = new SLMap(document.getElementById('map-container'), 
                          {hasZoomControls: false, hasPanningControls: false});
  mapInstance.centerAndZoomAtSLCoord(new XYPoint(997, 1002), 2);
  
  (document.getElementById('zoom_level')).innerHTML = mapInstance.getCurrentZoomLevel();
}

function setZoom(level) {
  mapInstance.setCurrentZoomLevel(level);
  (document.getElementById('zoom_level')).innerHTML = mapInstance.getCurrentZoomLevel();
}

function zoomIn() {
  mapInstance.zoomIn();
  (document.getElementById('zoom_level')).innerHTML = mapInstance.getCurrentZoomLevel();
}

function zoomOut() {
  mapInstance.zoomOut();
  (document.getElementById('zoom_level')).innerHTML = mapInstance.getCurrentZoomLevel();
}
</script>
</head>
<body onload="loadmap()" onunload="GUnload()">
<p>This map has the usual pan/zoom controls disabled, and the hyperlinks 
below implement custom pan/zoom controls via SLMap Javascript calls.
<h2>Set the zoom level</h2>
<h3>The Current Zoom Level is <span style='color:red' id='zoom_level'></span></h3>

<a href="javascript: setZoom(1);">1</a>
<a href="javascript: setZoom(2);">2</a>
<a href="javascript: setZoom(3);">3</a>
<a href="javascript: setZoom(4);">4</a>
<a href="javascript: setZoom(5);">5</a>
<a href="javascript: setZoom(6);">6</a>
<a href="javascript: setZoom(7);">7</a>
<a href="javascript: setZoom(8);">8</a>
<a href="javascript: zoomIn();">zoom in</a>
<a href="javascript: zoomOut();">zoom out</a>

<h2>Pan Around</h2>

<a href="javascript: mapInstance.panLeft();">left</a>
<a href="javascript: mapInstance.panRight();">right</a>
<a href="javascript: mapInstance.panUp();">up</a>
<a href="javascript: mapInstance.panDown();">down</a>
<br><br>
<div id="map-container"></div>
</body>

Disabling and enabling dragging

To disable dragging on the map, simply call disableDragging() on the map object. 

mapInstance.disableDragging();

When you are done call enableDragging() on the map object to re-enable dragging.

Example source code 

<!-- Insert common HTML header -->
<script>
var mapInstance;

function loadmap() {
  mapInstance = new SLMap(document.getElementById('map-container'));
  mapInstance.centerAndZoomAtSLCoord(new XYPoint(997, 1002), 2);
}

</script>
</head>
<body onload="loadmap()" onunload="GUnload()">
<p><a href="javascript: mapInstance.disableDragging();">Click to disable dragging map</a>
<p><a href="javascript: mapInstance.enableDragging();">Click to enable dragging map</a>

<div id="map-container"></div>
</body>

Panning or re-centering the map

Use the map object's panOrRecenterToSLCoord() method to pan the map to a specific point, providing the following parameters:

  • An XYPoint object, that identifies a specific x, y point.
  • Whether to recenter the map if the specified point is not currently visible. This parameter is optional and defaults to false.

For example: 

mapInstance.panOrRecenterToSLCoord(new XYPoint(1000, 1000), true);

The above code pans or recenters the map to (1000, 1000) depending on the current view.

Example source code 

<!-- Insert common HTML header --> 
<script>
var mapInstance;

function loadmap() {
  // creates the map
  mapInstance = new SLMap(document.getElementById('map-container'));
  mapInstance.centerAndZoomAtSLCoord(new XYPoint(998.5, 1001), 2);
  
  var mapWindow1 = new MapWindow("This is (997, 1002)");
  var mapWindow2 = new MapWindow("This is (1000, 1000)");
  var mapWindow3 = new MapWindow("This is (1010.5, 1000.5)");
  
  mapInstance.addMapWindow(mapWindow1, new XYPoint(997, 1002));
  mapInstance.addMapWindow(mapWindow2, new XYPoint(1000, 1000));
  mapInstance.addMapWindow(mapWindow3, new XYPoint(1010.5, 1000.5));
}

</script>
</head>
<body onload="loadmap()" onunload="GUnload()">
<p>Click the links to pan or re-center the map on the indicated co-ordinates:
<p><a href="javascript: mapInstance.panOrRecenterToSLCoord(new XYPoint(1000, 1000), true);">
Pan or recenter to (1000, 1000)</a></p>
<p><a href="javascript: mapInstance.panOrRecenterToSLCoord(new XYPoint(1010.5, 1000.5), true);">
Pan or recenter to (1010.5, 1000.5)</a></p>

<div id="map-container"></div>
</body>

Setting a onStateChangedHandler event handler

The map object has an onStateChangedHandler option that is a function called whenever the user pans or zooms the map. Specify it in the options when you initially create the map object. For example: 

mapInstance = new SLMap(document.getElementById('map-container'), {onStateChangedHandler: doSomething});

Whenever the user zooms or pans the map, the Webmap API will call the doSomething function.

This feature is handy when you want to show markers only currently in the user's viewport: in the event handler function, simply remove all the current markers, then place a new set of markers on the map based on the current map bounds.

Example source code 

<!-- Insert common HTML header -->  
<script>
function loadmap() {
  // creates the map
  mapInstance = new SLMap(document.getElementById('map-container'), 
                          {onStateChangedHandler: doSomething});
  mapInstance.centerAndZoomAtSLCoord(new XYPoint(997, 1002), 2);
}
function doSomething() {
  alert("The map state has changed!!");
}
</script>
</head>
<body onload="loadmap()" onunload="GUnload()">
<p>This map will display an alert whenever the map's state changes (i.e. the map is panned or zoomed)
<div id="map-container"></div>
</body>

Setting click and double-click event handlers

You can define a double click event handler function, that gets called when the user double-clicks on the map. For example: 

// creates a function that we will bind to the double click action
var doubleClickHandlerFunction = function(x,y) {
  alert("you double clicked at (" + x + "," + y + ")");
};

var clickHandlerFunction = function(x,y) {
  alert("you double clicked at (" + x + "," + y + ")");
};

// creates the map
var mapInstance = new SLMap(document.getElementById('map-container'),
                            {doubleClickHandler: doubleClickHandlerFunction
                             clickHandler: clickHandlerFunction});
mapInstance.centerAndZoomAtSLCoord(new XYPoint(997.5, 1001.5), 2);

This does not appear to work currently.

The above code pops up a Javascript alert box showing the X and Y coordinate clicked. The X and Y coordinate will be passed as parameters to event handler functions. Is this still true?

Example source code 

<!-- Insert common HTML header -->
<script>
function doubleClickHandlerFunction() {
      alert("You double-clicked!")
}

function clickHandlerFunction() {
      alert("You clicked!")
}

function loadmap() {
  // creates the map
  var mapInstance = new SLMap(document.getElementById('map-container'),
                              {doubleClickHandler: doubleClickHandlerFunction,
                                clickHandler: clickHandlerFunction});

  mapInstance.centerAndZoomAtSLCoord(new XYPoint(997, 1002), 2);
}

</script>
<body onload="loadmap()" onunload="GUnload()">
<p>There should be a yellow marker in the center of this map:
<div id="map-container"></div>
</body>

Getting current map center and bounds

Use the map object's getViewportBounds() method to get the bounds of the map. This method returns a Bounds object that has xMin, xMax, yMin, and yMax properties for the current viewport. For example: 

var bounds = mapInstance.getViewportBounds();

Use the map object's getMapCenter() method to get the coordinates of map. This method returns an XYPoint object representing the center of the map. For example: 

var center = mapInstance.getMapCenter();

These methods are handy to display only markers inside the current map viewport, or display markers based on the proximity from the map center.

Example source code 

<!-- Insert common HTML header -->
<script>
var mapInstance;

function loadmap() {
  // creates the map
  mapInstance = new SLMap(document.getElementById('map-container'));
  mapInstance.centerAndZoomAtSLCoord(new XYPoint(998.5, 1001), 2);
  
  var mapWindow1 = new MapWindow("This is (997, 1002)");
  var mapWindow2 = new MapWindow("This is (1000, 1000)");
  var mapWindow3 = new MapWindow("This is (1020, 1020)");
  
  mapInstance.addMapWindow(mapWindow1, new XYPoint(997, 1002));
  mapInstance.addMapWindow(mapWindow2, new XYPoint(1000, 1000));
  mapInstance.addMapWindow(mapWindow3, new XYPoint(1020, 1020)); 
  
  checkBounds();
}

function checkBounds() {
  var bounds = mapInstance.getViewportBounds();
  var center = mapInstance.getMapCenter();
  
  document.getElementById('cent').innerHTML = "(" + center.x + "," + center.y + ")";
  document.getElementById('xMin').innerHTML = bounds.xMin;
  document.getElementById('xMax').innerHTML = bounds.xMax;
  document.getElementById('yMin').innerHTML = bounds.yMin;
  document.getElementById('yMax').innerHTML = bounds.yMax;
}
</script>
</head>
<body onload="loadmap()" onunload="GUnload()">
<p>Drag/zoom the map and then <a href="javascript: checkBounds();">click here</a>
 to check the current viewport bounds and center coordinate</p>

<p>Center: <span id='cent'></span></p>
<p>X-Min: <span id='xMin'></span></p>

<p>X-Max: <span id='xMax'></span></p>
<p>Y-Min: <span id='yMin'></span></p>
<p>Y-Max: <span id='yMax'></span></p>
<div id="map-container"></div>
</body>

Working with markers

The Marker object displays a small image at a particular x, y point on the map.

Setting a marker's event handlers

The Marker object has three event handlers:

  • clickHandler - function called when user clicks on the marker.
  • mouseOverHandler - function called when user moves mouser pointer over marker.
  • mouseOutHandler - function called when user moves mouse pointer off marker.

Set these event handlers to Javascript functions when you construct the Map object. For example: 

// creates a function that we will bind to the marker click action
var doMarkerAction = function(marker) {
  alert("an event occured at (" + marker.slCoord.x + "," + marker.slCoord.y + ")");
};

// creates the marker and sets its event handlers
var marker = new Marker(all_images, 
                        new XYPoint(997, 1002), 
                        {clickHandler: doMarkerAction, 
                         onMouseOutHandler: doMarkerAction, 
                         onMouseOverHandler: doMarkerAction});

The code above simple sets all three event handlers of the marker to the doMarkerAction() function. The marker is passed as a parameter to this function.

Example source code 

<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
<style>
div#map-container1
{
      width: 400px;
      height: 400px;
}

div#map-container2
{
      width: 400px;
      height: 400px;
}
</style>

<script src="http://maps.google.com/maps?file=api&v=2&key=[GOOGLE MAP API KEY]"
  type="text/javascript"></script>
<script src="http://slurl.com/_scripts/slmapapi.js" type="text/javascript"></script>
<script>
// mapInstance and marker is set as a global, so that the removeMarker function can access them
var mapInstance, marker;

var myClickHandler = function(marker)
{
    alert("Click handler for marker at ("+ marker.slCoord.x + ", " + marker.slCoord.y + ")");
}

function loadmap() 
{
  // create the icons for use as a marker
  var yellow_dot_image = new Img("Yellow_marker.gif", 9, 9);
  var yellow_icon = new Icon(yellow_dot_image);
  var all_images = [yellow_icon, yellow_icon, yellow_icon, yellow_icon, yellow_icon, yellow_icon];
  
  // First map
  mapInstance1 = new SLMap(document.getElementById('map-container1'));
  mapInstance1.centerAndZoomAtSLCoord(new XYPoint(997, 1002), 2);
  
  // creates the marker
  marker1 = new Marker(all_images, new XYPoint(997, 1002));
  mapInstance1.addMarker(marker1);

  // Second map
  mapInstance2 = new SLMap(document.getElementById('map-container2'));
  mapInstance2.centerAndZoomAtSLCoord(new XYPoint(997, 1002), 2);
  
  // creates the marker
  marker2 = new Marker(all_images, new XYPoint(997, 1002), {clickHandler: myClickHandler});
  mapInstance2.addMarker(marker2);
}
</script>
</head>
<body onload="loadmap()" onunload="GUnload()">
<p>No clickhandler (default):
<div id="map-container1"></div>
<p>Click handler installed:
<div id="map-container2"></div>
</body>


Removing a marker

Call the map object's removeMarker() method to remove a marker, passing the marker object as the parameter. For example: 

mapInstance.removeMarker(myMarker);

The above code removes the marker myMarker.


Example source code 

<script>
<!-- Insert common HTML header -->
// mapInstance and marker are global, so removeMarker() can access them.
var mapInstance, marker;

function loadmap() {
  // Creates the map
  mapInstance = new SLMap(document.getElementById('map-container'));
  mapInstance.centerAndZoomAtSLCoord(new XYPoint(997, 1002), 2);
  
  // Creates the icons
  var yellow_dot_image = new Img("Yellow_marker.gif", 9, 9);
  var yellow_icon = new Icon(yellow_dot_image);
  var all_images = [yellow_icon, yellow_icon, yellow_icon, yellow_icon, yellow_icon, yellow_icon];
  
  // Creates the marker
  marker = new Marker(all_images, new XYPoint(997, 1002));
  mapInstance.addMarker(marker);
}

function removeMarker() {
  // Removes the marker
  mapInstance.removeMarker(marker);
}
</script>
</head>
<body onload="loadmap()" onunload="GUnload()">
<a href="javascript: removeMarker();">Click to remove the yellow marker from the map</a>
<div id="map-container"></div>
</body>

Triggering a marker click

To simulate clicking on a marker, use the Map object's clickMarker() method, passing the marker as the parameter. For example: 

mapInstance.clickMarker(marker);

This method can come in handy if you are listing links somewhere else on the page, and want links to open up markers with more information.

Creating markers with shadows

You can use a PNG image to make a marker appear to have a "shadow." To do this:

  • Create two Img objects, one for the marker image and one for the shadow image.
  • When creating the Img objects, provide "true" as the fourth argument to the constructor, indicating to create the image with an alpha channel (which provides transparency).
  • When creating the Icon object, provide both Img objects as arguments to the constructor.

For example: 

// creates the icons
var forsale_sign = new Img("forsale.png", 80, 83, true); // note how the fourth parameter is set true!
var forsale_shadow = new Img("forsale-shadow.png", 98, 83, true);
var forsale_icon = new Icon(forsale_sign, forsale_shadow);
var all_images = [forsale_icon, forsale_icon, forsale_icon, forsale_icon, forsale_icon, forsale_icon];

// creates the marker
var marker = new Marker(all_images, new XYPoint(995, 1004));
mapInstance.addMarker(marker);

Additional examples

Closing a map window automatically when user pans the map

<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
<style>
div#map-container {
      width: 500px;
      height: 500px;
}
</style>

<script src="http://maps.google.com/maps?file=api&v=2&key=[GOOGLE MAP API KEY]"
  type="text/javascript"></script>
<script src="http://slurl.com/_scripts/slmapapi.js" type="text/javascript"></script>
<script>
function loadmap() {
  // creates the map
  var mapInstance = new SLMap(document.getElementById('map-container'));
  mapInstance.centerAndZoomAtSLCoord(new XYPoint(997.5, 1001.5), 2);
  
  // creates a window
  var mapWindow = new MapWindow("This is where the welcome area fountain is!! <br><img src='fountain.gif'>",
                                {closeOnMove: true});
  mapInstance.addMapWindow(mapWindow, new XYPoint(997, 1002));
}
</script>
</head>
<body onload="loadmap()" onunload="GUnload()">
<p>When you drag this map, the info window should disappear:<br />
<div id="map-container"></div>
</body>

Aligning marker images

<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
<style>
div#map-container1
{
      width: 400px;
      height: 400px;
}

div#map-container2
{
      width: 400px;
      height: 400px;
}
</style>

<script src="http://maps.google.com/maps?file=api&v=2&key=[GOOGLE MAP KEY]"
  type="text/javascript"></script>
<script src="http://slurl.com/_scripts/slmapapi.js" type="text/javascript"></script>
<script>
// mapInstance and marker is set as a glabal, so that the removeMarker function can access them
var mapInstance, marker;

function loadmap() 
{
  // create the icons for use as a marker
  var yellow_dot_image = new Img("Yellow_marker.gif", 9, 9);
  var yellow_icon = new Icon(yellow_dot_image);
  var all_images = [yellow_icon, yellow_icon, yellow_icon, yellow_icon, yellow_icon, yellow_icon];
  
  // First map
  mapInstance1 = new SLMap(document.getElementById('map-container1'));
  mapInstance1.centerAndZoomAtSLCoord(new XYPoint(997, 1002), 2);
  
  // creates the marker
  marker1 = new Marker(all_images, new XYPoint(997,1002),
                        {verticalAlign: "top", horizontalAlign: "left"});
  mapInstance1.addMarker(marker1);

  // Second map
  mapInstance2 = new SLMap(document.getElementById('map-container2'));
  mapInstance2.centerAndZoomAtSLCoord(new XYPoint(997, 1002), 2);
  
  // creates the marker
  marker2 = new Marker(all_images, new XYPoint(997,1002), 
                        {verticalAlign: "bottom", horizontalAlign: "right"});
  mapInstance2.addMarker(marker2);
}
</script>
</head>
<body onload="loadmap()" onunload="GUnload()">
<p>Marker icon aligned to top-left:
<div id="map-container1"></div>
<p>Marker icon aligned to bottom-right:
<div id="map-container2"></div>
</body>

Centering the map on a marker when user clicks it

<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
<style>
div#map-container1
{
      width: 400px;
      height: 400px;
}

div#map-container2
{
      width: 400px;
      height: 400px;
}
</style>

<script src="http://maps.google.com/maps?file=api&v=2&key=[GOOGLE MAP KEY]"
  type="text/javascript"></script>
<script src="http://slurl.com/_scripts/slmapapi.js" type="text/javascript"></script>
<script>
// mapInstance and marker is set as a glabal, so that the removeMarker function can access them
var mapInstance, marker;

function loadmap() 
{
  // create the icons for use as a marker
  var yellow_dot_image = new Img("Yellow_marker.gif", 9, 9);
  var yellow_icon = new Icon(yellow_dot_image);
  var all_images = [yellow_icon, yellow_icon, yellow_icon, yellow_icon, yellow_icon, yellow_icon];
  
  // First map
  mapInstance1 = new SLMap(document.getElementById('map-container1'));
  mapInstance1.centerAndZoomAtSLCoord(new XYPoint(996,1001),2);
  
  // creates the marker
  marker1 = new Marker(all_images, new XYPoint(997,1002));
  mapInstance1.addMarker(marker1);

  // Second map
  mapInstance2 = new SLMap(document.getElementById('map-container2'));
  mapInstance2.centerAndZoomAtSLCoord(new XYPoint(996,1001),2);
  
  // creates the marker
  marker2 = new Marker(all_images, new XYPoint(997,1002), {centerOnClick: true});
  mapInstance2.addMarker(marker2);
}
</script>
</head>
<body onload="loadmap()" onunload="GUnload()">
<p>Clicking on this marker should have no effect:
<div id="map-container1"></div>
<p>Clicking on this marker should center the map on the marker:
<div id="map-container2"></div>
</body>


Controlling marker z-order

<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
<style>
div#map-container1
{
      width: 400px;
      height: 400px;
}

div#map-container2
{
      width: 400px;
      height: 400px;
}
</style>

<script src="http://maps.google.com/maps?file=api&v=2&key=[GOOGLE MAP KEY]"
  type="text/javascript"></script>
<script src="http://slurl.com/_scripts/slmapapi.js" type="text/javascript"></script>
<script>
// mapInstance and marker is set as a glabal, so that the removeMarker function can access them
var mapInstance, marker;

function loadmap() 
{
  // create the icons for use as a marker
  var marker1_image = new Img("marker_1.gif", 64, 64);
  var marker1_icon = new Icon(marker1_image);
  var marker1_images = [marker1_icon, marker1_icon, marker1_icon, marker1_icon, marker1_icon, marker1_icon];
  
  var marker2_image = new Img("marker_2.gif", 64, 64);
  var marker2_icon = new Icon(marker2_image);
  var marker2_images = [marker2_icon, marker2_icon, marker2_icon, marker2_icon, marker2_icon, marker2_icon];
  
  // First map
  var mapInstance1 = new SLMap(document.getElementById('map-container1'));
  mapInstance1.centerAndZoomAtSLCoord(new XYPoint(997, 1002), 2);
  
  // creates the marker
  var marker1a = new Marker(marker1_images, new XYPoint(997, 1002),
                        {zLayer: 1});
  mapInstance1.addMarker(marker1a);

  var marker1b = new Marker(marker2_images, new XYPoint(997.15, 1002.15),
                        {zLayer: 0});
  mapInstance1.addMarker(marker1b);

  // Second map
  mapInstance2 = new SLMap(document.getElementById('map-container2'));
  mapInstance2.centerAndZoomAtSLCoord(new XYPoint(997, 1002), 2);
  
  // creates the marker
  var marker2a = new Marker(marker1_images, new XYPoint(997, 1002),
                        {zLayer: 0});
  mapInstance2.addMarker(marker2a);

  var marker2b = new Marker(marker2_images, new XYPoint(997.15, 1002.15),
                        {zLayer: 1});
  mapInstance2.addMarker(marker2b);

}
</script>
</head>
<body onload="loadmap()" onunload="GUnload()">
<p>The '1' marker icon should be on top of the '2' marker icon:
<div id="map-container1"></div>
<p>The '2' marker icon should be on top of the '1' marker icon:
<div id="map-container2"></div>
</body>

Removing all markers from a map

<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
<style>
div#map-container {
      width: 500px;
      height: 500px;
}
</style>

<script src="http://maps.google.com/maps?file=api&v=2&key=[GOOGLE MAP KEY]"
  type="text/javascript"></script>
<script src="http://slurl.com/_scripts/slmapapi.js" type="text/javascript"></script>
<script>
// mapInstance and marker is set as a glabal, so that the removeMarker function can access them
var mapInstance, marker;

function loadmap() {
  // creates the map
  mapInstance = new SLMap(document.getElementById('map-container'));
  mapInstance.centerAndZoomAtSLCoord(new XYPoint(997, 1002), 2);
  
  // creates the icons
  var yellow_dot_image = new Img("Yellow_marker.gif", 9, 9);
  var yellow_icon = new Icon(yellow_dot_image);
  var all_images = [yellow_icon, yellow_icon, yellow_icon, yellow_icon, yellow_icon, yellow_icon];
  
  // creates the markers
  var marker = new Marker(all_images, new XYPoint(997,1002));
  mapInstance.addMarker(marker);
  marker = new Marker(all_images, new XYPoint(997.4,1002));
  mapInstance.addMarker(marker);
  marker = new Marker(all_images, new XYPoint(997.2,1002.8));
  mapInstance.addMarker(marker);
  marker = new Marker(all_images, new XYPoint(997.8,1002.2));
  mapInstance.addMarker(marker);
  marker = new Marker(all_images, new XYPoint(997.1,1002.65));
  mapInstance.addMarker(marker);
}

function removeAllMarkers() 
{
  // removes all the the marker
  mapInstance.removeAllMarkers();
}
</script>
</head>
<body onload="loadmap()" onunload="GUnload()">
<a href="javascript: mapInstance.removeAllMarkers();">Click to remove all the markers</a>
<div id="map-container"></div>
</body>

Example source code 

<!-- Insert common HTML header -->
<script>
function loadmap() {
  // creates the map
  var mapInstance = new SLMap(document.getElementById('map-container'));
  mapInstance.centerAndZoomAtSLCoord(new XYPoint(995,1004),2);
  
  // creates the icons
  var forsale_sign = new Img("forsale.png",80,83, true);
  var forsale_shadow = new Img("forsale-shadow.png", 98, 83, true);
  var forsale_icon = new Icon(forsale_sign, forsale_shadow);
  var all_images = [forsale_icon, forsale_icon, forsale_icon, forsale_icon, forsale_icon, forsale_icon];
  
  // creates the marker
  var marker = new Marker(all_images, new XYPoint(995, 1004));
  mapInstance.addMarker(marker);
}
</script>
</head>
<body onload="loadmap()" onunload="GUnload()">
<p>The map shows a 'for sale' sign marker with smooth edges, and an anti-aliased shadow.
<div id="map-container"></div>
</body>


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