Wayland Display/Inputs driver¶

Overview¶

The Wayland driver provides integration between LVGL and Wayland-based systems, allowing LVGL applications to render directly into a Wayland surface and handle keyboard, mouse and touch input. This makes it suitable for production deployments, such as kiosk interfaces, control panels, or other embedded GUIs where Wayland is the display server.

In addition to production use, the driver is also useful for development on linux desktop environments, offering a convenient way to simulate and validate your LVGL applications without dedicated hardware. It serves as an alternative to the X11 and SDL2 drivers.

Dependencies¶

The wayland driver requires some dependencies.

On Ubuntu

sudo apt-get install libwayland-dev libxkbcommon-dev libwayland-bin wayland-protocols

On Fedora

sudo dnf install wayland-devel libxkbcommon-devel wayland-utils wayland-protocols-devel

Rendering Backends¶

The Wayland driver supports multiple rendering backends, allowing you to choose the most appropriate rendering method for your hardware and use case.

SHM Backend (Default)¶

The SHM (Shared Memory) backend is the default rendering backend used by the Wayland driver. It uses Wayland's shared memory protocol (wl_shm) for rendering, which is supported across all Wayland compositors.

Features:

Double-buffered direct rendering
Universal compatibility with all Wayland compositors
No special hardware requirements

Limitations:

Rotation is not currently supported

Usage:

The SHM backend is enabled by default and requires no additional configuration.

G2D Backend¶

The G2D backend leverages NXP's hardware-accelerated 2D graphics engine available on i.MX processors. This backend provides improved performance on NXP platforms.

Features:

Hardware-accelerated rendering
Double-buffered direct rendering
Rotation support (0°, 90°, 180°, 270°)

Requirements:

Hardware with G2D support (e.g., NXP i.MX6/i.MX8 series)
G2D library and drivers installed on the system

Usage:

Enable the G2D backend in lv_conf.h:

#define LV_USE_DRAW_G2D  1

When LV_USE_DRAW_G2D is enabled, the Wayland driver will automatically use the G2D backend instead of the default SHM backend.

Configuring the wayland driver¶

Enable the wayland driver in lv_conf.h

#define LV_USE_WAYLAND  1

Reference Project¶

LVGL Linux port serves as a reference project for setting up wayland. It uses CMake to generate the required protocols at build time.

Getting started¶

In main.c #include "lv_drivers/wayland/wayland.h"
Enable the Wayland driver in lv_conf.h with LV_USE_WAYLAND 1
LV_COLOR_DEPTH should be set either to 32 or 16 in lv_conf.h
Add a display using lv_wayland_window_create(), possibly with a close callback to track the status of each display:

#define H_RES (800)
#define V_RES (480)

/* Create a display */
lv_disp_t * disp = lv_wayland_window_create(H_RES, V_RES, "Window Title", close_cb);

As part of the above call, the Wayland driver will register four input devices for each display:

a KEYPAD connected to Wayland keyboard events
a POINTER connected to Wayland touch events
a POINTER connected to Wayland pointer events
an ENCODER connected to Wayland pointer axis events

Handles for input devices of each display can be obtained using lv_wayland_get_indev_keyboard(), lv_wayland_get_indev_touchscreen(), lv_wayland_get_indev_pointer() and lv_wayland_get_indev_pointeraxis() respectively.

Fullscreen mode¶

To programmatically fullscreen the window, use the lv_wayland_window_set_fullscreen() function respectively with true or false for the fullscreen argument.

Maximized mode¶

To programmatically maximize the window, use the lv_wayland_window_set_maximized() function respectively with true or false for the maximized argument.

Minimize window¶

To programmatically minimize the window, use the lv_wayland_window_set_minimized() function.

Physical display assignment¶

When using multiple physical displays, you can control which display a fullscreen window appears on by assigning it to a specific physical display before entering fullscreen mode.

Use lv_wayland_assign_physical_display() to assign a window to a particular physical display, where the display parameter specifies the physical display number (typically 0, 1, 2, etc.):

/* Assign to physical display 0 and full screen on that display */
lv_wayland_assign_physical_display(disp, 0);
lv_wayland_window_set_fullscreen(window, true);

To remove the physical display assignment and return to default behavior, use lv_wayland_unassign_physical_display():

lv_wayland_unassign_physical_display(disp);

Building the Wayland Driver¶

The reference project uses CMakeLists to generate the necessary dependencies at build time.

Mainly, the project generates the necessary protocols with the wayland-scanner utility.

The wayland protocols are defined using XML files which are present in /usr/share/wayland-protocols

By default, LVGL relies on the xdg-shell protocol for window management to generate it run the following commands:

wayland-scanner client-header $SYSROOT/usr/share/wayland-protocols/stable/xdg-shell/xdg-shell.xml wayland_xdg_shell.h
wayland-scanner private-code $SYSROOT/usr/share/wayland-protocols/stable/xdg-shell/xdg-shell.xml wayland_xdg_shell.c

When LV_WAYLAND_USE_DMABUF is set to 1, the following protocols must also be generated:

wayland-scanner client-header $SYSROOT/usr/share/wayland-protocols/stable/linux-dmabuf/linux-dmabuf-v1.xml wayland_linux_dmabuf.h
wayland-scanner private-code $SYSROOT/usr/share/wayland-protocols/stable/linux-dmabuf/linux-dmabuf-v1.xml wayland_linux_dmabuf.c

The resulting files can then be integrated into the project, it's better to re-run wayland-scanner on each build to ensure that the correct versions are generated, they must match the version of the wayland-client dynamically linked library installed on the system.

Window Decorations¶

Note

As of LVGL v9.5, the LV_WAYLAND_WINDOW_DECORATIONS option has been removed.

Window decorations (title bars, borders, close buttons, etc.) are now the responsibility of the application developer, not LVGL. This change gives you full control over the appearance and behavior of your window decorations.

Creating Window Decorations¶

You can create your own window decorations using LVGL widgets. For example, use the Window (lv_win) widget to add a title bar with buttons, or build custom decorations from basic widgets like containers, labels, and buttons.

This approach allows you to: - Design decorations that match your application's style - Add custom controls and functionality - Maintain consistent UI across different Wayland compositors - Have complete control over the look and feel

For applications that don't need decorations (fullscreen, kiosk mode, etc.), simply create your UI without them.

Current state and objectives¶

EGL Support
Server-side window decorations
Rotation support for the SHM backend

Bug reports¶

The wayland driver is currently under construction, bug reports, contributions and feedback are always welcome.

It is however important to create detailed issues when a problem is encountered, logs and screenshots of the problem are of great help.

Please enable LV_USE_LOG and launch the simulator executable like so

WAYLAND_DEBUG=1 ./path/to/simulator_executable > /tmp/debug 2>&1

This will create a log file called debug in the /tmp directory, copy-paste the content of the file in the github issue. The log file contains LVGL logs and the wayland messages.

Be sure to replicate the problem quickly otherwise the logs become too big