Triggers and Interactivity

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Triggers allow defining set of rules for triggering specific seq or par playlist.

Defining Triggers 

The <triggers> element define a pool of individual <trigger> tags.

  • whenever the <condition> is TRUE, trigger is set as activate.
  • whenever the <condition> is FALSE, trigger is set as deactivate.

The id of the <trigger> has to be unique and start with trigger key word - e.g. trigger1, trigger-my-content, triggerABC.

<head>
    <triggers>
        <trigger id="trigger1" condition="or">
            <!-- 
            If sensor - RFID antenna rfid1- emits
            that user picked up an RFID tag with ID 1 
            condition is set to TRUE 
            and trigger activated
             -->
            <condition 
                origin="rfid1" <!-- Trigger origin, usually defined in <sensor/> tag -->
                data="1" <!-- Data passed from origin sensor, in this case RFID tag ID -->
                action="picked" <!-- user action emitted by the origin sensor -->
            />
        </trigger>
        <!-- you can add as many triggers as you need -->
        <trigger id="trigger2" condition="or">
            <!-- also number of condition is limited only by device performance -->
            <condition origin="rfid1" data="2" action="picked"/>
            <condition origin="rfid1" data="3" action="picked"/>
            <condition origin="rfid5" data="4" action="picked"/>
            <condition origin="rfid6" data="5" action="picked"/>
        </trigger>
    </triggers>

</head>

Mandatory Sub-Regions for triggered playlist

To make sure triggers will work fine with other non triggered content in other regions, you have to define a sub-region where the triggered playlists are going to be played.

Any triggered playlist will be played in the trigger-sub-region1.

The regionName can be named as you want. There is no restriction.

More about general usage of Regions can be found here. This is an advanced use case.

Usage of the sub-regions

Sub-region is defined a child tag of another <region>.

<region regionName="trigger-region">
    <region regionName="trigger-sub-region1"/>
</region>
  1. The trigger-sub-region1 can completely occupy the parent <region>:
<region regionName="trigger-region" left="10" top="10" width="1280" height="720">
    <!-- Single sub-region filling the parent region completely -->
    <region regionName="trigger-sub-region1" 
            left="0" 
            top="0" 
            width="100%" 
            height="100%"
    />
</region>
  1. The trigger-region can be split into multiple sub-regions.
<region regionName="trigger-region" left="10" top="10" width="1280" height="720">
    <!-- Two sub-regions positioned relatively to the parent region -->
    <region regionName="trigger-sub-region1" 
            left="0" 
            top="0" 
            width="50%" 
            height="100%"
    />
    <region regionName="trigger-sub-region2" 
            left="50%" 
            top="0" 
            width="50%" 
            height="100%"
    />
</region>

Having multiple sub-regions allows you to play multiple triggered content with a dynamic location. The example flow of the dynamically assigning sub-regions is as follows:

  • first, trigger2 will start playback in the first available sub-region of the trigger-region -> trigger-sub-region1
  • secondly, trigger1 will be initiated while still having trigger2 activated -> the playlist for trigger1 will be automatically assigned to the trigger-sub-region2

Triggered playlist is always looking for the first available (empty) sub-region. If no sub-region is available (all are occupied by the previously triggered playlists), it overrides the first sub-region.

Triggering content

To trigger content by the pre-defined triggers use trigger id in the begin attribute of the <seq> or <par> element.

The triggered playlist is automatically stopped whenever the condition defined in <head> is no longer TRUE.

For media and other elements always set region attribute to the parent one. Never use sub-regions in the region attribute.

<par>
    <!-- referencing <trigger id="trigger1"> defined in <head>  -->
    <seq begin="trigger1"> 
        <video src="smil/zones/files/video_3.mp4" 
            region="trigger-region"> <!-- As a region you always set the parent of the sub-regions -->
        </video>
        <video src="/smil/zones/files/video_3.mp4" 
            region="trigger-region"> <!-- As a region you always set the parent of the sub-regions -->
        </video>
    </seq>
</par>

<par>
    <!-- referencing <trigger id="trigger2"> defined in <head>  -->
    <seq begin="trigger2"> 
        <video src="smil/samples/assets/landscape1.mp4" 
            region="trigger-region"> <!-- As a region you always set the parent of the sub-regions -->
        </video>
    </seq>
</par>

Duration of the triggered content

If you need the triggered content to play more than one time, you can adjust the number of playback by using repeatCount:

<par>
    <!-- referencing <trigger id="trigger2"> defined in <head>  -->
    <seq begin="trigger2" repeatCount="3"> 
        <video src="smil/samples/assets/landscape1.mp4" 
            region="trigger-region"> <!-- As a region you always set the parent of the sub-regions -->
        </video>
    </seq>
</par>

Or you can specify dur attribute to determine exactly how long should be trigger playing. Dur is specified in seconds.

<par>
    <!-- referencing <trigger id="trigger2"> defined in <head>  -->
    <seq begin="trigger2" dur="30"> 
        <video src="smil/samples/assets/landscape1.mp4" 
            region="trigger-region"> <!-- As a region you always set the parent of the sub-regions -->
        </video>
    </seq>
</par>
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