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Difference between revisions of "API:Events"

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There are several different types of events that you can respond to. In general, each type of object has a corresponding event for changes, additions, and removals. Each event will be triggered once per object that changes. If more than one property on the object changes at the same time, only one "global" event (e.g. change:graphic) is triggered.
 
There are several different types of events that you can respond to. In general, each type of object has a corresponding event for changes, additions, and removals. Each event will be triggered once per object that changes. If more than one property on the object changes at the same time, only one "global" event (e.g. change:graphic) is triggered.
  

Revision as of 20:23, 23 April 2013

Roll20 API

Getting Started


Reference


Cookbook (Examples)


Community Scripts

There are several different types of events that you can respond to. In general, each type of object has a corresponding event for changes, additions, and removals. Each event will be triggered once per object that changes. If more than one property on the object changes at the same time, only one "global" event (e.g. change:graphic) is triggered.

Callback Parameters

When you listen to an event, you create a function known as a callback that is executed anytime the event occurs. The callback function receives several parameters which are objects that tell you information you want to know about the event so you can decide what to do.

Callback paramters for each event will vary, but include:

obj

The object that was changed. Any changes you make to this object will also be saved to the game. So if you want to move a Graphic object to the left, you would modify the left property of obj using set.

  • obj.get("property") returns the current value for the property.
  • obj.set("property", "newvalue") sets a new value for the property. If you're changing several properties at once you can pass an object: obj.set({left: 10, top: 20});
  • obj.previous("property") gets the previous value for the property. This can be used in event callbacks to determine "how much" a property has changed.


Campaign Events

ready

This event fires after all the current data for the campaign has been loaded. So if you want to find a list of all objects in a campaign, or a specific object that is already in the Campaign, be sure to only look for it after the ready event fires. In addition, if you bind to add events (such as add:graphic) before the ready event fires, you will receive add events for objects that were already present in the campaign.

on("ready", function() {
  var tokenThatAlreadyExisted = getObj("graphic", "-ABc123");
});

change:campaign:playerpageid

Fired whenever the page that the players are currently on changes.

change:campaign:_turnorder (Read Only)

Fired whenever the turn order listing for the campaign changes.

change:campaign:initiativepage

Fired whenever the turn order is hidden or shown for a page. This may not be the same as the ID of the currently active page. If this is set to false (including if an API script sets it to false), it will close the turn order for all GMs/players. Setting it to a valid page ID will open it for all GMs/players.


Object Events

change:graphic

Triggered whenever a Graphic object (which is almost any type of object on the tabletop, including tokens, maps, and cards) changes.

Callback paramters: obj

on("change:graphic", function(obj) {    
  //Do something with "obj" here
});


change:graphic:(property)

You can also bind to an event for each specific property on the object. So if you have a script that you want to run only when the rotation changes, you would do:

on("change:graphic:rotation", function(obj) {    
  //Always set rotation back to 0, so no one can rotate objects.    
  obj.set("rotation", 0);
});

add:graphic

Triggered whenever a graphic object is added to the tabletop for the first time. Will also be called for existing objects when the tabletop starts up if you bind to this event outside of the ready event.

Callback parameters: obj

on("add:graphic", function(obj) {
  //Will be called for all new graphics, including ones that already existed at the start of the play session.
});

var started = false;

on("ready", function() {
  on("add:graphic", function(obj) {
    //Will only be called for new objects that get added, since existing objects have already been loaded before the ready event fires.
  });
  //You could also set a variable and ignore add events until it is true.
  started = true;
});

destroy:graphic

Triggered whenver a graphic object was removed from the tabletop.

Callback parameters: obj

Other Object Types

There are also events for all the other object types, and sub-types, such as:

change:path, add:path, destroy:path, change:text, add:text, destroy:text, change:token, add:token, destroy:token, change:card, add:card, destroy:card

See the Objects reference for a complete list of all object types and sub-types.