libliftoff/include/libliftoff.h

#ifndef LIFTOFF_H
#define LIFTOFF_H

#include <stdarg.h>
#include <stdbool.h>
#include <stdint.h>
#include <stddef.h>
#include <xf86drmMode.h>

struct liftoff_device;
struct liftoff_output;
struct liftoff_layer;

/**
 * Initialize libliftoff for a DRM node.
 *
 * The node is expected to have DRM_CLIENT_CAP_ATOMIC enabled. libliftoff takes
 * ownership of the file descriptor.
 */
struct liftoff_device *liftoff_device_create(int drm_fd);
/**
 * Destroy a libliftoff device.
 *
 * The caller is expected to destroy the outputs and layers explicitly.
 */
void liftoff_device_destroy(struct liftoff_device *device);
/**
 * Build a layer to plane mapping and append the plane configuration to `req`.
 *
 * Callers are expected to commit `req` afterwards and can read the layer to
 * plane mapping with `liftoff_layer_get_plane_id`.
 *
 * `flags` is the atomic commit flags the caller intends to use.
 */
bool liftoff_output_apply(struct liftoff_output *output, drmModeAtomicReq *req,
			  uint32_t flags);

/**
 * Make the device manage a CRTC's planes.
 *
 * The returned output allows callers to attach layers.
 */
struct liftoff_output *liftoff_output_create(struct liftoff_device *device,
					     uint32_t crtc_id);
/**
 * Destroy a libliftoff output.
 *
 * The caller is expected to destroy the output's layers explicitly.
 */
void liftoff_output_destroy(struct liftoff_output *output);
/**
 * Indicate on which layer composition can take place.
 *
 * Users should be able to blend layers that haven't been mapped to a plane to
 * this layer. The composition layer won't be used if all other layers have been
 * mapped to a plane. There is at most one composition layer per output.
 */
void liftoff_output_set_composition_layer(struct liftoff_output *output,
					  struct liftoff_layer *layer);

/**
 * Create a new layer on an output.
 *
 * A layer is a virtual plane. Users can create as many layers as they want and
 * set any KMS property on them, without any constraint. libliftoff will try
 * to map layers to hardware planes on a best-effort basis. The user will need
 * to manually handle layers that couldn't be mapped to a plane.
 */
struct liftoff_layer *liftoff_layer_create(struct liftoff_output *output);
/**
 * Destroy a layer.
 */
void liftoff_layer_destroy(struct liftoff_layer *layer);
/**
 * Set a property on the layer.
 *
 * Any plane property can be set (except CRTC_ID). If none of the planes support
 * the property, the layer won't be mapped to any plane.
 *
 * Setting a zero FB_ID disables the layer.
 */
void liftoff_layer_set_property(struct liftoff_layer *layer, const char *name,
				uint64_t value);
/**
 * Force composition on this layer.
 *
 * This unsets any previous FB_ID value. To switch back to direct scan-out, set
 * FB_ID again.
 *
 * This can be used when no KMS FB ID is available for this layer but it still
 * needs to be displayed (e.g. the buffer cannot be imported in KMS).
 */
void liftoff_layer_set_fb_composited(struct liftoff_layer *layer);
/**
 * Retrieve the plane mapped to this layer.
 *
 * Zero is returned if no plane is mapped.
 */
uint32_t liftoff_layer_get_plane_id(struct liftoff_layer *layer);

enum liftoff_log_importance {
	LIFTOFF_SILENT,
	LIFTOFF_ERROR,
	LIFTOFF_DEBUG,
};

typedef void (*liftoff_log_func)(enum liftoff_log_importance importance,
				 const char *fmt, va_list args);

/**
 * Initialize libliftoff's log infrastructure.
 *
 * Only messages with a priority higher than the provided `verbosity` will be
 * logged. If `callback` is non-NULL, libliftoff will call the function instead
 * of printing the messages to stderr.
 */
void liftoff_log_init(enum liftoff_log_importance verbosity,
		      liftoff_log_func callback);

#endif