Tracking Status API
You can use a JavaScript event called trackingstatuschanged to obtain information about changes to the tracking status of a target. The trackingstatuschanged event has a JSON payload that contains a key-value pair, with trackingStatus as the key and a status string value:
{"trackingStatus":"<tracking_status>"}
In the string above, the <tracking_status> variable can be any of the following statuses:
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Status
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Description
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normal
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The target is being tracked and indicates normal operation.
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extended
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The target is being tracked indirectly. It is either out of view, occluded, too far, or too close to be tracked directly.
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limited
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The target is being tracked but with very low accuracy.
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limited_excessive_motion
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Tracking is limited because the device is being moved too quickly.
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This status is only reported for Model Targets.
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limited_insufficient_light
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Tracking is limited because of poor lighting conditions.
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This status is only reported for Model Targets.
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The event handler implemented in JavaScript has the following signature:
function(event, target, tmlNodeName, args)
The following is a table that lists and describes the available parameters:
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Parameter
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Description
|
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event
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The event object. This contains the trackingstatuschanged string for the name property.
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target
|
Name or ID of the target.
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This will be an empty string for Spatial Targets.
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tmlNodeName
|
Type of the object. The value will be twx-dt-target for this event.
|
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args
|
String that includes the JSON event data.
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Example
The following is an example implementation of the JavaScript event handler:
$scope.$on("trackingstatuschanged", function (event, target, tmlNodeName, args) {
trackingStatus = JSON.parse(args).trackingStatus;
console.log("Tracking Status Changed Script: event: " + event.name + ", target: " + target + ", tmlNodeName: " + tmlNodeName + ", args:" + args + ", trackingStatus: " + trackingStatus);
});
The following is an example of the log output:
Tracking Status Changed Script: event: trackingstatuschanged, target: 740de1d2-6202-45ab-94db-1056ecf2244b, tmlNodeName: twx-dt-target, args:{"trackingStatus":"extended"}, trackingStatus: extended
