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

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=== Zoom levels ===
=== Zoom levels ===
There are eight zoom levels: one through eight, one being the closest and eight being the farthest. Each level zooms by a power of two. In other words, at zoom level five, each region is twice the width as it was at zoom level six.
There are eight zoom levels: one through eight, one being the closest and eight being the farthest. Each level zooms by a power of two. In other words, at zoom level five, each region is twice the width as it was at zoom level six.
== Basic Examples ==
See [http://slurl.com/examples/ Second Life Map API Examples] to see these examples in action.
=== Required image files ===
Some of the following examples use image files for markers.  To run the examples with the code as shown, download the image files and save them in the same directory as the example HTML files.  Alternatively, create the Img objects using the URLs listed in the table below that refer to the images stored on this wiki.
The following table lists the images used in the examples:
{| {{Prettytable}}
|-{{Hl2}}
! Image
! File name
! URL
|-
| [[Image:Yellow marker.gif]]
| b_map_yellow.gif
| <br>http://slurl.com/examples/b_map_yellow.gif
|-
| [[Image:Fountain.gif]]
| fountain.gif
| http://slurl.com/examples/fountain.gif
|-
| [[Image:Forsale.png]]
| forsale.png
| http://slurl.com/examples/forsale.png
|-
|[[Image:Forsale-shadow.png]]
| forsale-shadow.png
|http://slurl.com/examples/forsale-shadow.png
|}
=== Simple map ===
The first example is a map with basic panning and zooming capabilities.  When you are done, it will look as shown here.
[[Image:MapAPI ex1.png|thumb|right|Simple map]]
You can pan the map and zoom in and out.
To create this example, follow these steps:
# Add common HTML header code.
# Add HTML body element.
# Add '''loadmap()''' function.
# Save and test.
<br clear="all"/>
'''1. Add common HTML header'''
First, include the [[Webmap_API#Common_HTML_header|common header code]], required by all Webmap applications. 
<pre><nowiki>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
<script src="http://slurl.com/_scripts/slmapapi.js" type="text/javascript"></script>
<script src="http://maps.google.com/maps?file=api&amp;v=2&amp;key={GOOGLE MAPS KEY}" type="text/javascript"></script>
<link rel="stylesheet" type="text/css" href="http://slurl.com/_styles/MAIN.css" />
<style>
div#map-container {
      width: 500px;
      height: 500px;
}
</style>
...
</head>
</nowiki></pre>
Be sure to replace {GOOGLE MAPS KEY} with your Google Map key.
'''2. Add HTML body element'''
Next, add the HTML body element to contain your map. The body contains a Javascript onload event handler that calls the '''loadmap()''' function you will define in the next step.
<pre>
<body onload="loadmap()" onunload="GUnload()">
  <div id="map-container"></div>
</body>
</pre>
The div element is passed to the SLMap object constructor, using the  <code>document.getElementById('map-container')</code> DOM method call.
NOTE: If you want the position attribute of the div element to be absolute, either set it programmatically using Javascript or using the style attribute tag.  Setting the position attribute of this element in the CSS stylesheet will not work.
'''3. Add loadmap() function'''
The body element you just added has a Javascript event handler for the "onload" event, called when the browser initially loads the page.  You deifined this to call a '''loadmap()''' function.  Now, define that Javascript function in the head of your page (after the code that is already there), as follows:
<script>
function loadmap() {
  mapInstance = new SLMap(document.getElementById('map-container'));
  mapInstance.centerAndZoomAtSLCoord(new XYPoint(997, 1002), 3);
}
</script>
The first line defines a new Map object from the HTML div element.  The second line centers the map at a specific point, and zooms it to zoom level three.
'''4. Save and test'''
When you are done, save the file, and then load it into your web browser.  Try panning the map by clicking and dragging the mouse cursor; you can also pan by clicking on the arrow icons on the four sides.  Also try zooming the view in and out by clicking the "+" and "-" icons.
'''Complete source code'''
<pre>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
<script src="http://maps.google.com/maps?file=api&v=2&key=[GOOGLE MAPS KEY]" type="text/javascript"></script>
<script src="http://slurl.com/_scripts/slmapapi.js" type="text/javascript"></script>
<link rel="stylesheet" type="text/css" href="http://slurl.com/_styles/MAIN.css" />
<style>
div#map-container {
      width: 500px;
      height: 500px;
}
</style>
<script>
function loadmap() {
  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>
</body>
</pre>
=== Map with a marker ===
[[Image:Map with Marker.png|thumb|right|Map with a marker]]
A ''marker'' is simply an image displayed at a specific location on the map.  The Map API enables you to define an image for each zoom level, so the marker can appear differently at each zoom level if you wish.
This example shows how to make a map with a marker. The code is the same as the first example, with with addition of some Javascript after the initialization of the map in the page's onload event handler function, '''loadmap()'''.
To use the code below verbatim, you must download the marker image as described in [[#Required_image_files|Required image files]]; you can also use the URL of the wiki image if you prefer. 
The code first creates the icon for the marker, then places it on the map at (997, 1002) at the welcome area fountain.  Because the same icon is specified for every zoom level, it appears the same size regardless of zoom level.
<br clear="all"/>
<pre>
// Create the icons
var yellow_dot_image = new Img("b_map_yellow.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];
// Create the marker
var marker = new Marker(all_images, new XYPoint(997, 1002));
mapInstance.addMarker(marker);
</pre>
In this example, clicking on the marker does nothing.  Subsequent examples illustrate adding some onClick behavior.
'''Source code'''
Replace the first line comment below with the [[Webmap_API#Common_HTML_header|common header code]].
<pre>
<!-- Insert common HTML header -->
<script>
function loadmap() {
  // creates the map
  var mapInstance = new SLMap(document.getElementById('map-container'));
  mapInstance.centerAndZoomAtSLCoord(new XYPoint(997, 1002), 2);
 
  // creates the icons
  var yellow_dot_image = new Img("b_map_yellow.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
  var marker = new Marker(all_images, new XYPoint(997, 1002));
  mapInstance.addMarker(marker);
}
</script>
</head>
<body onload="loadmap()" onunload="GUnload()">
<p>There should be a yellow marker in the center of this map:
<div id="map-container"></div>
</body>
</pre>
=== Map with an initial open window ===
[[Image:Map_with_window.png|thumb|right|Map with a window]]
A Webmap ''window'' is a caption pointing to a specific point on the map, as shown in the screenshot at right.  It looks something like a comic book dialog bubble. 
Use the [[Webmap_API_Reference#MapWindow|MapWindow]] object to create a window.
For example, to create a window that opens initially when the page loads:
# Instantiate a [[Webmap_API_Reference#MapWindow|MapWindow]] object with the desired caption.
# Call the '''addMapWindow()''' method on the [[Webmap_API_Reference#SLMap|SLMap]] object to add the window to the map.
<br clear="all"/>
For example:
<pre>
// creates a window
var mapWindow = new MapWindow("This is where the welcome area fountain is!!");
mapInstance.addMapWindow(mapWindow, new XYPoint(997, 1002));
</pre>
The code adds an open window to the map positioned again at (997, 1002), right above the welcome area fountain.
NOTE: after the user closes the window there is no way to bring it back.  A subsequent example will show how to enable the user to reopen the window, by using markers with windows.
<br clear="all"/>
To make the map initially centered on the fountain, change the call to '''centerAndZoomAtSLCoord()''' as follows:
  mapInstance.centerAndZoomAtSLCoord(new XYPoint(997, 1002), 3);
'''Source code'''
This example shows how to create a map with a window. The code is the same as the first example, with the addition of some lines of Javascript after the initialization of the map, in the '''loadmap()''' function. In addition, the map is centered in a different location in order to make the window fully visible.
Replace the first line comment below with the [[Webmap_API#Common_HTML_header|common header code]].
<pre>
<!-- Insert common HTML header -->
<script>
function loadmap() {
  mapInstance = new SLMap(document.getElementById('map-container'));
  mapInstance.centerAndZoomAtSLCoord(new XYPoint(997, 1002), 3);
 
  // Create window
var mapWindow = new MapWindow("This is where the welcome area fountain is!!");
mapInstance.addMapWindow(mapWindow, new XYPoint(997, 1002));
}
</script>
</head>
<body onload="loadmap()" onunload="GUnload()">
  <h1>Simple Map Example</h1>
  <div id="map-container"></div>
</body>
</pre>
=== Map with a marker that opens a window ===
[[Image:Map with marker and window.png|thumb|right|Map with marker that opens a window]]
This example shows how to create a map with a marker which opens a window when clicked.  It is a combination of the previous two examples, because the code first creates a marker and a window. 
The difference comes in adding the marker to the map: this time you provide the window object as well as the marker object in the call to '''addMarker()''':
mapInstance.addMarker(marker, mapWindow);
Doing this adds the marker and causes it to open the specified window when the user clicks it.  If the user subsequently closes the window, s/he can open it again by clicking on the marker.
<br clear="all" />
'''Source code'''
Replace the first line comment below with the [[Webmap_API#Common_HTML_header|common header code]].
<pre>
<!--- Insert common HTML header --->
<script>
function loadmap() {
  // Create the map
  var mapInstance = new SLMap(document.getElementById('map-container'));
  mapInstance.centerAndZoomAtSLCoord(new XYPoint(997.5, 1001.5), 2);
 
  // Create the icons
  var yellow_dot_image = new Img("b_map_yellow.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];
 
  // Create the marker
  var marker = new Marker(all_images, new XYPoint(997, 1002));
 
  // Create a window
  var mapWindow = new MapWindow("This is where the welcome area fountain is!! <br><img src='fountain.gif'>");
 
  // Adds the marker to the map
  mapInstance.addMarker(marker, mapWindow);
}
</script>
</head>
<body onload="loadmap()" onunload="GUnload()">
<p>This map shows a yellow marker on the welcome fountain.  When you click the marker,
a window appears with a screenshot of the fountain.</p>
<div id="map-container"></div>
</body>
</pre>


== Accessing map images directly ==
== Accessing map images directly ==

Revision as of 09:19, 26 October 2010

Getting Started

The Second Life Map API is a set of Javascript objects and functions that enable you to embed Second Life maps onto your web pages. It is a purely client-side Javascript API. If needed, you can also directly access the map images.

NOTE: This API is still in beta. URLs and API signatures may change. See the Release Notes for information on new features and known issues.

Map UI features

The Map API enables you to create web pages that have Google Maps functionality, using maps of Second Life, rather than Earth. In general, the default map interface looks as shown here.

Map ui cropped.png

The main map display area shows the current map area. By default, the map provides the following features:

  • Click and drag the mouse pointer to pan the map view up, down, left, and right. If desired, you can disable this behavior.
  • Double-click to zoom in by one level (power of two) and display the teleport window.
  • Click anywhere on the map to open a "teleport" window; see Teleport window below.
  • Use the mouse wheel to zoom in and out. See Zoom levels for more information about zoom levels.
  • Use the zoom and pan controls at upper left to zoom the view in and out and to pan the view up, down, left, and right. If desired, you can easily create your own custom zoom and pan controls.
  • Use the overview control to move the view around by clicking and dragging, or double-clicking. Close the overview control by clicking on the diagonal arrow at the very bottom right of the map. You can specify whether the map provides an overview control when you create the map object.


Teleport window

Teleport window.png

Clicking anywhere on the map opens a window, such as the one shown at left, indicating the point on which you clicked. Clicking on the teleport button in the window then starts the Second Life Viewer, automatically teleporting you to the window's location. This feature is implemented with the gotoSLURL() global function.


Working examples

See http://slurl.com/examples/ for a set of working Map API examples.

Using slurl.com and DirectSLurl

The website http://slurl.com uses the Map API to provide a mechanism to teleport directly to locations in Second Life from web pages.

For more information, see Using Second Life URLs (SLURLs).

Prerequisites

To use the Second Life Map API in a web page, you must first:

NOTE: In general, it is best to reference the Map API Javascript library and CSS files that are on http://slurl.com. Although you can download these files locally and modify them for your own use, if Linden Lab updates or changes these files, your applications will not get the benefit and may even stop working properly.

Common HTML header

To use the Map API, put the following lines at the beginning of each HTML page. This includes:

  • Statements to load the required Second Life Map API and Google Maps Javascript libraries.
  • Link to the Webmap cascading style sheet.
  • Style declaration for the map div element. This defines the size and other layout attributes of the map display.
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
<script src="http://maps.google.com/maps?file=api&v=2&key={GOOGLE MAPS KEY}"
  type="text/javascript"></script>
<script src="http://slurl.com/_scripts/slmapapi.js" type="text/javascript"></script>

<link rel="stylesheet" type="text/css" href="http://slurl.com/_styles/MAIN.css" />
<style>
div#map-container {
      width: 500px;
      height: 500px;
}
</style>
...

Replace {GOOGLE MAPS KEY} with you Google Maps Key.

All the examples also require additional script statements in the HTML header.

Stylesheet

To use your own stylesheet, just include it AFTER the Webmap CSS, for example: 

<link rel="stylesheet" type="text/css" href="http://slurl.com/_styles/MAIN.css" />
<link rel="stylesheet" type="text/css" href="myStyleSheet.css" />

Body element

Use the following body element in your HTML document: 

<body load="loadmap()" onunload="GUnload();">
...

The GUnload() function is a Google Maps API function that reduces memory leaks, particularly with Internet Explorer. For more information, see the Google Maps API documentation.

Browser compatibility

The Map API has been tested to work with the following browsers:

  • Internet Explorer 6.0
  • Internet Explorer 7.0
  • Firefox 2.0 or greater
  • Safari 2.0

Other browsers may work but little issues may appear. Unless otherwise noted, all features work in all supported browsers.

Comments and feedback

If you encounter problems or bugs or have feature requests, please email webmap@secondlife.com.

Happy coding from the Second Life Web team!

Basic concepts

The Map API's fundamental class is SLMap. It is a Javascript object representing the map with a large number of methods, enabling you to zoom, pan the view, and so on.

Additionally, the API includes the following key classes:

  • Marker - represents an image to display at a specify (x,y) point on the map. You provide a set of images to display at each zoom level. Contains several event handlers and other properties. See Map with a marker for a basic example.
  • Window - represents a captioned balloon pointing to a specified map location. See Map with an initial open window for a basic example.
  • Img and Icon - represent an image to use for markers, controls, or in windows.

About coordinates

Map coordinates are based on the Second Life grid system for positioning regions.

Webmap coords.jpg

As illustrated in the diagram above, the Map API maps the Second Life world to the upper right quadrant of the Google world map. A large scaling value called slGridEdgeSizeInRegions (equal to 220 or 1,048,576) defines the largest region coordinate at the top and far right edge of the displayed area. This value creates a map area with room for one trillion sims.

The little blue square illustrates where the populated sims are in Second Life.

Zoom levels

There are eight zoom levels: one through eight, one being the closest and eight being the farthest. Each level zooms by a power of two. In other words, at zoom level five, each region is twice the width as it was at zoom level six.

Accessing map images directly

The Second Life map images are stored on Amazon Simple Storage Service (Amazon S3). You can access the map images directly on the Amazon S3 servers using the following URL format (new as of February 10, 2009): 

http://map.secondlife.com/map-Z-X-Y-objects.jpg

Where:

  • Z - Zoom level desired:
    • One (1) is the most zoomed-in view, showing individual region tiles.
    • Eight (8) is the maximum zoom level, showing the entire world.
  • X,Y - X and Y coordinates on the Second Life Grid of the region, for example, region Ahern is (997,1002).

Tiles with zoom greater than one are stored at the lower left corner coordinate of the tiles that are included in the image. In other words, you can find the zoom tile containing region (X,Y) for zoom level Z with the filename map-Z-X'-Y'-objects.jpg where:

X' = X - (X % (2Z - 1) )

and

Y' = Y - (Y % (2Z - 1) )

Note that 2Z - 1 is the number of regions encompassed by the width of a tile at resolution Z.

Examples

For example: if Z = 1, the four region tiles are:

These four region tiles are compressed into the single tile:

http://map.secondlife.com/map-2-1000-1000-objects.jpg

The following shows the map zoomed all the way out, showing the entire Second Life world view: http://map.secondlife.com/map-8-1024-896-objects.jpg

The following displays a single tile contained in the view above, zoomed all the way in: http://map.secondlife.com/map-1-1027-1019-objects.jpg

Implementation notes

The map generation process is more scalable than the previous release, and is able to image the entire Second Life grid of about 30,000 regions in less than two days.

There is a "decay period" for offline regions. If a region is disabled, the tile will stay up for several days (in case it comes back or something else has gone wrong) before the tile disappears. That several-day period will be longer than the time it takes to update existing regions or put new regions on the map.

Getting a map URL from LSL

The following LSL script illustrates how to display a map of the current region to an avatar:

<lsl> ShowMap(key avatar) { 

   string url = "http://map.secondlife.com/";
   vector sim_coord = llGetRegionCorner();
   string x = (string)((integer)(sim_coord.x / 256.0));
   string y = (string)((integer)(sim_coord.y / 256.0));
   url += "map-1-" + x + "-" + y + "-objects.jpg";
   llLoadURL(avatar, "View the sim map", url);

} </lsl>

Release notes

This section describes new features and known issues with the current release of the Map API. See also Philip Linden's blog post announcement.

The current version of the Map API was released on Jan 15, 2009.

New features

This release of the Map API provides significant performance improvements over the previous release, including:

  • Map loads faster and operates more smoothly.
  • Map images are updated more accurately and rapidly. Changes to the Second Life Grid or content will now be visible within about two days.
  • Map images look smoother and are more accurate when compared to the actual in-world content.

Changes in functionality:

  • You can now single-click on any location on the map and teleport directly there.
  • Zoom levels go up to eight, so you can now zoom out and see how big SL has really become!
  • More intuitive map tile image file naming convention.

The Map API now gets map tile images directly from Amazon S3, and the file naming convention will make it easier to develop other third party maps based on the tiles we are generating.

Known issues

  • Map object click and doubleclick handlers do not work. They always have the default behavior.
  • Method SLMap.clickMarker(marker) doesn't work.
  • Marker options do not work:
    • centerOnClick: true - This works, but does NOT work if you open a window onclicking the marker.
    • autopanOnClick: false - Always autopans
    • autopanPadding: n - No effect
  • Setting a different marker image/icon for each zoom level doesn't work - always uses first icon.
  • Window width option doesn't work.
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