Web Display

How to use the Web Display robot skill

Shows a web page on a monitor plugged into the robot's computer: a robot face, a dashboard, a video call, or a locked-down kiosk screen. It works on Windows and Linux, including a Raspberry Pi, and on Linux it does not need a desktop - a bare X server is enough (see INSTALL, Browser windows).

Pages can talk back. A button on a touch screen can set global variables and run a script, so a visitor pressing "Wave" makes the robot wave.

This is the screen on the robot itself. The ARCx interface you are using now can be on any computer or phone on the network; the Web Display page appears on the monitors attached to the computer that runs ARCx.

Many instances are allowed: one per screen, or one per page you switch between.

Adding it to a project

1. Add the skill (Display category).
2. Open its configuration, enter the Web Page address, and pick the Display Mode and Monitor.
3. Save. With Open On Project Load on, the page opens now and every time the project loads.

The window

• Open / Close - show or close the page.
• Reload, Home - reload the page, or go back to the configured address after a visitor has navigated away.
• Display mode - switch between Windowed, Fullscreen and Kiosk without opening the configuration.
• The page's title and address, and a log of what happened: loads, failures, messages from the page.

If browser windows cannot open on this computer the window says why. Views, Browser Windows has the details and the monitor list; the Diagnostics page explains problems such as a missing X server on Linux.

Configuration

Setting	Meaning	Default
Web Page	The address to show. https://, http://, or a file path. example.com is enough.	https://synthiam.com
Display Mode	Windowed: an ordinary window. Fullscreen: covers the monitor. Kiosk: fullscreen and locked down - no menus or keyboard shortcuts, always on top, reopens if closed, shows a retry page while offline, and keeps the screen awake.	Fullscreen
Monitor	Which monitor, numbered as Views, Browser Windows lists them. Primary monitor is -1.	Primary
Open On Project Load	Show the page when the project loads.	On
Camera And Microphone	Let the page use them, for video calls. There is no prompt on the robot's screen - these switches decide.	Off
Hide Mouse Pointer	For touch screens.	Off
Zoom	Page zoom in percent, 25 to 500.	100
Window Name	The name scripts use with the Browser commands. Empty uses this skill's title.	empty
Allowed Addresses	Keep the page on these addresses, one per line, * matching anything. Empty allows all.	empty
Accept Self-Signed Certificates	For a device on your own network with a self-signed HTTPS certificate.	Off
Custom CSS	Added to every page, for example to hide a site's header.	empty
Message Variables	Prefix of the variables a page message sets.	$WebDisplay
On Message Script	Runs every time the page sends a message.	empty
Log History	Lines kept in the log.	25

Changing the configuration while the page is open applies it straight away.

The Window tab sets the robot skill's window title, its size on the workspace and notes about what it does in this project.

Messages from the page

A page shown by this skill has a window.ARCx object. When it calls

window.ARCx.send('command', 'wave');

the skill sets $WebDisplayTopic to command and $WebDisplayData to wave, then runs the On Message Script, which can look at the variables and act:

if (getVar("$WebDisplayTopic") == "command" && getVar("$WebDisplayData") == "wave")
  controlCommand("Auto Position", "AutoPositionAction", "Wave");

Objects work too: ARCx.send('move', { direction: 'left' }) stores the JSON text {"direction":"left"} in the data variable.

Going the other way, the SendMessage ControlCommand (or Browser.sendMessage() in a script) delivers a message to the page, which listens with window.ARCx.on('mood', function (data) { ... }).

A page made for a normal browser as well should check if (window.ARCx) first, because the object only exists in an ARCx browser window.

Tips

• A kiosk that is closed with the Close button or ControlCommand stays closed. Closed any other way, it comes back by itself.
• If the page is black or blank on Linux, turn off GPU acceleration in Views, Browser Windows.
• Removing the skill closes its page.

Control Commands for the Web Display robot skill

There are Control Commands available for this robot skill which allows the skill to be controlled programmatically from scripts or other robot skills. These commands enable you to automate actions, respond to sensor inputs, and integrate the robot skill with other systems or custom interfaces. If you're new to the concept of Control Commands, we have a comprehensive manual available here that explains how to use them, provides examples to get you started and make the most of this powerful feature.

Control Command Manual

This robot skill has 11 control commands, listed below. Send them from a JavaScript or Python script, from Blockly, or from another robot skill.

The first value is always the window title, which is the name in the title bar of the robot skill on your workspace. It starts out as Web Display, which is what every example below uses. If you rename the robot skill, or add a second copy of it to the project, use the title as it appears on that window instead.

ControlCommand() can be shortened to CC(), and both spellings work in JavaScript and in Python. The examples are JavaScript; Python is the same call, except that true and false are written True and False.

Close

Close the window

Syntax

ControlCommand("Web Display", "Close")

Returns: nothing

Example

ControlCommand("Web Display", "Close");

Evaluate

Run a JavaScript expression in the page and return its value as text

Syntax

ControlCommand("Web Display", "Evaluate", (String)expression)

Parameters

#	Name	Type	What to pass
1	expression	Text	Your text, in quotes

Returns: String

Example

var result = ControlCommand("Web Display", "Evaluate", "expression");

GetUrl

The address the window is showing, or empty when it is closed

Syntax

ControlCommand("Web Display", "GetUrl")

Returns: String

Example

var result = ControlCommand("Web Display", "GetUrl");

Home

Go back to the page the window was opened with

Syntax

ControlCommand("Web Display", "Home")

Returns: nothing

Example

ControlCommand("Web Display", "Home");

IsOpen

Is the window open?

Syntax

ControlCommand("Web Display", "IsOpen")

Returns: Boolean [true or false]

Example

var result = ControlCommand("Web Display", "IsOpen");

MoveToMonitor

Move the window to another monitor, numbered from 0. -1 is the primary monitor

Syntax

ControlCommand("Web Display", "MoveToMonitor", (Number)monitor)

Parameters

#	Name	Type	What to pass
1	monitor	Number	A number, without quotes

Returns: nothing

Example

ControlCommand("Web Display", "MoveToMonitor", 0);

Open

Show the configured page. Re-points the window if it is already open

Syntax

ControlCommand("Web Display", "Open")

Returns: nothing

Example

ControlCommand("Web Display", "Open");

OpenUrl

Show another page in this skill's window, opening it if needed

Syntax

ControlCommand("Web Display", "OpenUrl", (String)url)

Parameters

#	Name	Type	What to pass
1	url	Text	Your text, in quotes

Returns: nothing

Example

ControlCommand("Web Display", "OpenUrl", "url");

Reload

Reload the page

Syntax

ControlCommand("Web Display", "Reload")

Returns: nothing

Example

ControlCommand("Web Display", "Reload");

SendMessage

Send a message to the page's window.ARCx.on(topic, handler)

Syntax

ControlCommand("Web Display", "SendMessage", (String)topic, (String)data)

Parameters

#	Name	Type	What to pass
1	topic	Text	Your text, in quotes
2	data	Text	Your text, in quotes

Returns: nothing

Example

ControlCommand("Web Display", "SendMessage", "topic", "data");

SetDisplayMode

Switch the window to Windowed, Fullscreen or Kiosk

Syntax

ControlCommand("Web Display", "SetDisplayMode", "Fullscreen")

Parameters

#	Name	Type	What to pass
1	"Fullscreen"	Text	The fixed value "Fullscreen". Leave it as it is.

Returns: nothing

Example

ControlCommand("Web Display", "SetDisplayMode", "Fullscreen");

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This list is read out of the robot skill itself each time its package is uploaded, so it matches the published version (v3).