libliftoff

Lightweight hardware composer library for libdrm.

libliftoff eases the use of KMS planes from userspace without standing in your way. Users create "virtual planes" called layers, set KMS properties on them, and libliftoff will allocate planes for these layers if possible.

Resources:

• Blog post introducing the project
• FOSDEM 2020 talk

Building

Depends on libdrm. Requires universal planes and atomic.

meson build/
ninja -C build/

Usage

See liftoff.h. Here's the general idea:

struct liftoff_device *device;
struct liftoff_output *output;
struct liftoff_layer *layer;
drmModeAtomicReq *req;
int ret;

device = liftoff_device_create(drm_fd);
output = liftoff_output_create(device, crtc_id);

layer = liftoff_layer_create(output);
liftoff_layer_set_property(layer, "FB_ID", fb_id);
/* Probably setup more properties and more layers */

req = drmModeAtomicAlloc();
if (!liftoff_output_apply(output, req)) {
	perror("liftoff_output_apply");
	exit(1);
}

ret = drmModeAtomicCommit(drm_fd, req, DRM_MODE_ATOMIC_NONBLOCK, NULL);
if (ret < 0) {
	perror("drmModeAtomicCommit");
	exit(1);
}
drmModeAtomicFree(req);

Contributing

Report bugs and send pull requests on GitHub.

We use the Wayland/Weston style and contribution guidelines, see Weston's contributing document.

License

MIT