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Setting the Video Call Layout

SignalWire Video API allows you to host real-time video calls and conferences on your website. In this guide, we'll learn to set layouts during video calls.

SignalWire video calls are composited at SignalWire servers so that everyone gets the same video feed. This means that layout changes are reflected instantly in each participant’s video stream. Each participant sees the same video layout once the layout switch occurs.

Requesting the necessary permission

Changing layouts is a privilege you must explicitly request when asking the SignalWire Video REST API for an access token. The endpoint to request access tokens is described in the SignalWire Video API reference guide.

In particular, you need to specify room.list_available_layouts and room.set_layout permissions when requesting the token. Ideally, this should happen on the server-side after you verify that the user requesting the access token actually has the privilege to change your video call's layout. In the Node.js/Express.js example below, we are indiscriminately handing out the permissions to anyone who requests a token. This is only to keep the code simple and does not reflect real-world usage.

app.post("/get_token", async (req, res) => {
let { user_name } = req.body;
console.log("Received name", user_name);
try {
let token = await axios.post(
apiurl + "/room_tokens",
{
user_name,
room_name: ROOMNAME,
permissions: ["room.set_layout", "room.list_available_layouts"]
},
{ auth }
);
console.log(token.data.token);
return res.json({ token: token.data.token });
} catch (e) {
console.log(e);
return res.sendStatus(500);
}
});
curl --request POST \
--url https://demo.signalwire.com/api/video/room_tokens \
--header 'Accept: application/json' \
--header 'Authorization: Basic bmV2ZXIgZ29ubmEgZ2l2ZTp5b3UgdXA=' \
--header 'Content-Type: application/json' \
--data '
{
"permissions": [
"room.set_layout"
],
"room_name": "example_room",
"user_name": "example_user"
}
'

Changing Layout with the Video JS SDK

As described in the SignalWire Video JS SDK guide, you first want to instantiate a room session with the access token acquired in the previous section.

const roomSession = new SignalWire.Video.RoomSession({
token: '<Your JWT with room.set_layout permission>',
rootElement: document.getElementById('myRoot'), // an html element to display the video
audio: true,
video: true,
})

try {
await roomSession.join()
} catch (error) {
console.error('Error', error)
}

The roomSession object exposes methods for getting and setting layouts.

The RoomSession.getLayouts() Method

To know what layouts the video feed supports, use the Room.getLayoutList() method. This needs to be supported from the server by specifying a room.list_available_layouts permission when requesting token.

roomSession.getLayouts().then(list => console.log(list.layouts));

/*
Outputs an array like:
[
"8x8",
"2x1",
"1x1",
...
]
*/

The RoomSession.setLayout() Method

To set the video call's layout to one of the layouts from the layout's list, use the Room.setLayout() method.

roomSession.setLayout({name: "10x10"}).then(output => console.log(output));

If calling the .setLayout() method throws an insufficient permission error, then the access token you are using to instantiate the Room object wasn't given the room.set_layout permission. Learn more about the access tokens permission list in the docs.

Demo

You can try using and tinkering with the sample program below on CodeSandbox: https://codesandbox.io/s/affectionate-tharp-rucj7

This demo was built in the Simple Video Demo. If you're having trouble understanding this demo, get started over there before adding layout in this guide.

Key Points

  1. Each participant of the video call sees the same video stream, so layout changes are reflected uniformly across all participants.
  2. Only the users with room.list_available_layouts can see the list of available layouts for the room.
  3. Only the users with the room.set_layout permission can change the video feed’s layout. This permission needs to be requested when requesting the room’s access token.
  4. You can get the list of supported layouts using Room.getLayouts() method.
  5. You can change the video call's layout using Room.setLayout({name: "<layout-name>"}).