Working with multiple displays and SimpleSwitch™

If you are running with multiple displays at a time, e.g. LVDS and HDMI, you can select the screen a graphical SimpleSwitch™ package runs on.

For that create a file at /apps/desktop-config/screens

$ mkdir -p /apps/desktop-config/
$ touch /apps/desktop-config/screens

within this file you can, per SimpleSwitch™ package, configure the screen

DISPLAY_<simpleswitch package>=<display name>

e.g.

DISPLAY_simpleswitch_test=LVDS-1

Important note

You will need to replace - characters in the SimpleSwitch™ package by _, e.g. the setting for simpleswitch-flutter-tractor becomes

DISPLAY_simpleswitch_flutter_tractor=LVDS-1

The names of the supported display can be found with

$ cat /run/simplecore-weston.ini | grep -C 2 "output" | grep "name" | cut -d'=' -f2
HDMI-A-1
LVDS-1

Specified displays that are not present will be ignored, letting the SimpleSwitch™ package start up on the primary display.

Qt applications

For Qt based application also a software patch is required.

Before the mainWindow->showFullScreen(); call in your application, you will need to add the following code snippet

bool ok;
int screen_number = qgetenv("QT_SCREEN").toInt(&ok, 10);
if (!ok || (screen_number - 1) > app.screens().count()) screen_number = 0;

mainWindow->setScreen(app.screens()[screen_number]);

// Start of your original application
mainWindow->showFullScreen();

Mapping the touchscreen

In addition if your display does support a touchscreen, you will need to let the system know which display the touch support belongs to.

Please see the guide at How to map a touchscreen, but you can configure through the file /apps/desktop-config/touchscreens.json