examples: add input-timestamp-v1 example

The client simply requests input-timestamps resources for both the
keyboard and the pointer, and prints all relevant events with their more
precise timestamps when they arrive. Touch support is not implemented as
of now.

examples/input-timestamps-unstable-v1.c

+#define _POSIX_C_SOURCE 200809L
+
+#include <GLES2/gl2.h>
+#include <assert.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <time.h>
+#include <wayland-egl.h>
+#include <wlr/render/egl.h>
+#include "xdg-shell-client-protocol.h"
+#include "input-timestamps-unstable-v1-client-protocol.h"
+
+/**
+ * global state of the client
+ */
+
+struct egl_info {
+	struct wlr_egl *egl;
+
+	struct wl_egl_window *egl_window;
+	struct wlr_egl_surface *egl_surface;
+	struct wl_surface *surface;
+
+	uint32_t width;
+	uint32_t height;
+
+	struct wl_callback *frame_callback;
+};
+
+struct client {
+	struct egl_info *egl_info;
+
+	struct wl_pointer *pointer;
+	struct wl_keyboard *keyboard;
+
+	struct zwp_input_timestamps_v1 *pointer_input_timestamps;
+	struct zwp_input_timestamps_v1 *keyboard_input_timestamps;
+
+	struct timespec pointer_timestamp;
+	struct timespec keyboard_timestamp;
+};
+
+/**
+ * global declarations
+ */
+
+static struct wl_shm *shm = NULL;
+static struct wl_compositor *compositor = NULL;
+static struct wl_seat *seat = NULL;
+static struct xdg_wm_base *xdg_wm_base = NULL;
+static struct zwp_input_timestamps_manager_v1 *input_timestamps_manager = NULL;
+
+static const struct wl_registry_listener registry_listener;
+static const struct wl_seat_listener seat_listener;
+static const struct wl_pointer_listener pointer_listener;
+static const struct wl_keyboard_listener keyboard_listener;
+static const struct xdg_surface_listener xdg_surface_listener;
+static const struct xdg_toplevel_listener xdg_toplevel_listener;
+static const struct zwp_input_timestamps_v1_listener input_timestamps_listener;
+
+const int WIDTH = 100;
+const int HEIGHT = 100;
+
+struct timespec cur, cur_rep;
+void update_current_time(void);
+void print_time_and_latency(uint32_t, struct timespec);
+void paint_pixels(struct egl_info *);
+
+/**
+ * registry and globals handling
+ */
+
+static void registry_handle_global(void *data, struct wl_registry *registry,
+		uint32_t name, const char *interface, uint32_t version) {
+	if (strcmp(interface, wl_shm_interface.name) == 0) {
+		shm = wl_registry_bind(registry, name,
+			&wl_shm_interface, version);
+	} else if (strcmp(interface, wl_compositor_interface.name) == 0) {
+		compositor = wl_registry_bind(registry, name,
+			&wl_compositor_interface, version);
+	} else if (strcmp(interface, wl_seat_interface.name) == 0) {
+		seat = wl_registry_bind(registry, name,
+			&wl_seat_interface, version);
+		wl_seat_add_listener(seat, &seat_listener, data);
+	} else if (strcmp(interface, xdg_wm_base_interface.name) == 0) {
+		xdg_wm_base = wl_registry_bind(registry, name,
+			&xdg_wm_base_interface, version);
+	} else if (strcmp(interface, zwp_input_timestamps_manager_v1_interface.name) == 0) {
+		input_timestamps_manager = wl_registry_bind(registry, name,
+			&zwp_input_timestamps_manager_v1_interface, version);
+	}
+}
+
+static void registry_handle_global_remove(void *data, struct wl_registry *registry,
+		uint32_t time) {
+	/* This space intentionally left blank */
+}
+
+static const struct wl_registry_listener registry_listener = {
+	.global = registry_handle_global,
+	.global_remove = registry_handle_global_remove,
+};
+
+/**
+ * wl_seat handling
+ */
+
+static void seat_handle_capabilities(void *data, struct wl_seat *seat,
+		enum wl_seat_capability caps) {
+	struct client *c = (struct client *) data;
+
+	/* Setup the pointer */
+
+	if ((caps & WL_SEAT_CAPABILITY_POINTER)) {
+		struct wl_pointer *pointer = wl_seat_get_pointer(seat);
+		wl_pointer_add_listener(pointer, &pointer_listener, c);
+
+		c->pointer = pointer;
+	}
+
+	/* Setup the keyboard */
+
+	if ((caps & WL_SEAT_CAPABILITY_KEYBOARD)) {
+		struct wl_keyboard *keyboard = wl_seat_get_keyboard(seat);
+		wl_keyboard_add_listener(keyboard, &keyboard_listener, c);
+
+		c->keyboard = keyboard;
+	}
+}
+
+static void seat_handle_name(void *data, struct wl_seat *seat,
+		const char *name) {
+	/* This space intentionally left blank */
+}
+
+static const struct wl_seat_listener seat_listener = {
+	.capabilities = seat_handle_capabilities,
+	.name = seat_handle_name,
+};
+
+/**
+ * wl_pointer handling
+ *
+ * It simply prints the relevant pointer events (button press, motion, axis
+ * movement) along with the associated timestamps, both coarse and fine
+ * (through the input-timestamps object).
+ */
+
+static void pointer_handle_button(void *data, struct wl_pointer *pointer,
+		uint32_t serial, uint32_t time, uint32_t button, uint32_t state) {
+	update_current_time();
+
+	if (state == WL_POINTER_BUTTON_STATE_PRESSED) {
+		fprintf(stdout, "POINTER: Button press %"PRIu32" (", button);
+		print_time_and_latency(time, ((struct client *) data)->pointer_timestamp);
+		fprintf(stdout, ")\n");
+	}
+}
+
+static void pointer_handle_enter(void *data, struct wl_pointer *wl_pointer,
+		uint32_t serial, struct wl_surface *surface,
+		wl_fixed_t surface_x, wl_fixed_t surface_y) {
+	/* This space intentionally left blank */
+}
+
+static void pointer_handle_leave(void *data, struct wl_pointer *wl_pointer,
+		uint32_t serial, struct wl_surface *surface) {
+	/* This space intentionally left blank */
+}
+
+static void pointer_handle_motion(void *data, struct wl_pointer *wl_pointer,
+		uint32_t time, wl_fixed_t surface_x, wl_fixed_t surface_y) {
+	update_current_time();
+
+	fprintf(stdout, "POINTER: Motion to (%f,%f) (",
+		wl_fixed_to_double(surface_x), wl_fixed_to_double(surface_y));
+	print_time_and_latency(time, ((struct client *) data)->pointer_timestamp);
+	fprintf(stdout, ")\n");
+}
+
+static void pointer_handle_axis(void *data, struct wl_pointer *wl_pointer,
+		uint32_t time, uint32_t axis, wl_fixed_t value) {
+	update_current_time();
+
+	fprintf(stdout, "POINTER: Axis %"PRIu32" by vector %f (",
+		axis, wl_fixed_to_double(value));
+	print_time_and_latency(time, ((struct client *) data)->pointer_timestamp);
+	fprintf(stdout, ")\n");
+}
+
+static void pointer_handle_frame(void *data, struct wl_pointer *wl_pointer) {
+	/* This space intentionally left blank */
+}
+
+static void pointer_handle_axis_source(void *data,
+		struct wl_pointer *wl_pointer, uint32_t axis_source) {
+	/* This space intentionally left blank */
+}
+
+static void pointer_handle_axis_stop(void *data,
+		struct wl_pointer *wl_pointer, uint32_t time, uint32_t axis) {
+	update_current_time();
+
+	fprintf(stdout, "POINTER: Axis %"PRIu32" stopped (", axis);
+	print_time_and_latency(time, ((struct client *) data)->pointer_timestamp);
+	fprintf(stdout, ")\n");
+}
+
+static void pointer_handle_axis_discrete(void *data,
+		struct wl_pointer *wl_pointer, uint32_t axis, int32_t discrete) {
+	/* This space intentionally left blank */
+}
+
+static const struct wl_pointer_listener pointer_listener = {
+	.enter = pointer_handle_enter,
+	.leave = pointer_handle_leave,
+	.motion = pointer_handle_motion,
+	.button = pointer_handle_button,
+	.axis = pointer_handle_axis,
+	.frame = pointer_handle_frame,
+	.axis_source = pointer_handle_axis_source,
+	.axis_stop = pointer_handle_axis_stop,
+	.axis_discrete = pointer_handle_axis_discrete,
+};
+
+/**
+ * wl_keyboard handling
+ *
+ * It simply prints the keypress events along with the associated timestamps,
+ * both coarse and fine (through the input-timestamps object).
+ */
+
+static void keyboard_handle_keymap(void *data, struct wl_keyboard *wl_keyboard,
+		uint32_t format, int32_t fd, uint32_t size) {
+	/* This space intentionally left blank */
+}
+
+static void keyboard_handle_enter(void *data, struct wl_keyboard *wl_keyboard,
+		uint32_t serial, struct wl_surface *surface, struct wl_array *keys) {
+	/* This space intentionally left blank */
+}
+
+static void keyboard_handle_leave(void *data, struct wl_keyboard *wl_keyboard,
+		uint32_t serial, struct wl_surface *surface) {
+	/* This space intentionally left blank */
+}
+
+static void keyboard_handle_key(void *data, struct wl_keyboard *wl_keyboard,
+		uint32_t serial, uint32_t time, uint32_t key, uint32_t state) {
+	update_current_time();
+
+	if (state == WL_KEYBOARD_KEY_STATE_PRESSED) {
+		fprintf(stdout, "KEYBOARD: Key press %"PRIu32" (", key);
+		print_time_and_latency(time, ((struct client *) data)->keyboard_timestamp);
+		fprintf(stdout, ")\n");
+	}
+}
+
+static void keyboard_handle_modifiers(void *data, struct wl_keyboard *wl_keyboard,
+		uint32_t serial, uint32_t mods_depressed, uint32_t mods_latched,
+		uint32_t mods_locked, uint32_t group) {
+	/* This space intentionally left blank */
+}
+
+static void keyboard_handle_repeat_info(void *data, struct wl_keyboard *wl_keyboard,
+		int32_t rate, int32_t delay) {
+	/* This space intentionally left blank */
+}
+
+static const struct wl_keyboard_listener keyboard_listener = {
+	.keymap = keyboard_handle_keymap,
+	.enter = keyboard_handle_enter,
+	.leave = keyboard_handle_leave,
+	.key = keyboard_handle_key,
+	.modifiers = keyboard_handle_modifiers,
+	.repeat_info = keyboard_handle_repeat_info,
+};
+
+/**
+ * xdg_surface handling
+ */
+
+static void xdg_surface_handle_configure(void *data,
+		struct xdg_surface *xdg_surface, uint32_t serial) {
+	xdg_surface_ack_configure(xdg_surface, serial);
+
+	struct egl_info *e = data;
+	wl_egl_window_resize(e->egl_window, e->width, e->height, 0, 0);
+	paint_pixels(e);
+}
+
+static const struct xdg_surface_listener xdg_surface_listener = {
+	.configure = xdg_surface_handle_configure,
+};
+
+/**
+ * xdg_toplevel handling
+ */
+
+static void xdg_toplevel_handle_configure(void *data,
+		struct xdg_toplevel *xdg_toplevel, int32_t width, int32_t height,
+		struct wl_array *states) {
+	struct egl_info *e = data;
+
+	if (width == 0 && height == 0) {
+		return;
+	}
+	e->width = width;
+	e->height = height;
+}
+
+static void xdg_toplevel_handle_close(void *data,
+		struct xdg_toplevel *xdg_toplevel) {
+	struct egl_info *e = data;
+	wlr_egl_finish(e->egl);
+
+	exit(EXIT_SUCCESS);
+}
+
+static const struct xdg_toplevel_listener xdg_toplevel_listener = {
+	.configure = xdg_toplevel_handle_configure,
+	.close = xdg_toplevel_handle_close,
+};
+
+/**
+ * input_timestamps handling
+ *
+ * We simply store the received timestamp in the timespec struct pointed to by
+ * the user data.
+ */
+
+static void input_timestamps_handle_timestamp(void *data,
+		struct zwp_input_timestamps_v1 *zwp_input_timestamps_v1,
+		uint32_t tv_sec_hi, uint32_t tv_sec_lo, uint32_t tv_nsec) {
+	struct timespec *timestamp = data;
+
+	timestamp->tv_sec = ((uint64_t) tv_sec_hi << 32) + tv_sec_lo;
+	timestamp->tv_nsec = tv_nsec;
+}
+
+static const struct zwp_input_timestamps_v1_listener input_timestamps_listener = {
+	.timestamp = input_timestamps_handle_timestamp,
+};
+
+/**
+ * helper functions:
+ *
+ * paint_pixels():
+ * Sets all pixels of the EGL surface to a fixed color.
+ *
+ * update_current_time():
+ * Updates the global clocks with two samples.
+ *
+ * print_time_and_latency():
+ * Prints the input event timestamps, along with estimated latency measured by
+ * the previous function.
+ */
+
+inline void paint_pixels(struct egl_info *e) {
+	eglMakeCurrent(e->egl->display, e->egl_surface, e->egl_surface,
+		e->egl->context);
+	glViewport(0, 0, e->width, e->height);
+
+	glClearColor(1.0f, 1.0f, 1.0f, 1.0f); /* white */
+	glClear(GL_COLOR_BUFFER_BIT);
+
+	eglSwapBuffers(e->egl->display, e->egl_surface);
+}
+
+inline void update_current_time(void) {
+	clock_gettime(CLOCK_MONOTONIC, &cur);
+	clock_gettime(CLOCK_MONOTONIC, &cur_rep);
+}
+
+inline void print_time_and_latency(uint32_t event_time_msec, struct timespec protocol_time) {
+		fprintf(stdout, "time: %"PRIu32" ms (event), %ld%09ld ns (protocol); ",
+			event_time_msec, protocol_time.tv_sec, protocol_time.tv_nsec);
+
+	if (event_time_msec/1000 == protocol_time.tv_sec) {
+		double input_time, first_sample, second_sample;
+		input_time = protocol_time.tv_sec + ((double) protocol_time.tv_nsec)/1000000000;
+		first_sample = cur.tv_sec + ((double) cur.tv_nsec)/1000000000;
+		second_sample = cur_rep.tv_sec + ((double) cur_rep.tv_nsec)/1000000000;
+		assert((second_sample > first_sample) && (first_sample > input_time));
+		fprintf(stdout, "latency: %f ms",
+			1000 * (first_sample - input_time - (second_sample - first_sample)));
+	} else {
+		fprintf(stdout, "latency: error!");
+	}
+}
+
+/**
+ * input-timestamps:
+ *
+ * This client serves as an example for the input-timestamps-unstable-v1
+ * protocol.
+ *
+ * The client requests a input timestamps object for the keyboard and the
+ * pointer -- if possible -- and prints all timed events as they come. Future
+ * directions could include capturing touch events, and toggling reporting for
+ * specific input devices via command line flags.
+ *
+ * We need a minimal toplevel to grab focus to receive input events. We use EGL
+ * (with helper functions from wlroots) to display a solid colored rectangle as
+ * an xdg toplevel.
+ *
+ */
+
+int main(int argc, char **argv) {
+
+	/* Connect to the display */
+
+	struct wl_display *display = wl_display_connect(NULL);
+	if (display == NULL) {
+		fprintf(stderr, "Could not connect to a Wayland display\n");
+		return EXIT_FAILURE;
+	}
+
+	/* Setup global state */
+
+	struct client *c = calloc(1, sizeof(struct client));
+
+	/* Get the registry and set listeners */
+
+	struct wl_registry *registry = wl_display_get_registry(display);
+	wl_registry_add_listener(registry, &registry_listener, c);
+	wl_display_dispatch(display);
+	wl_display_roundtrip(display);
+
+	/* Check that all the global interfaces were captured */
+
+	if (shm == NULL) {
+		fprintf(stderr, "wl_shm not available\n");
+		return EXIT_FAILURE;
+	}
+	if (compositor == NULL) {
+		fprintf(stderr, "wl_compositor not available\n");
+		return EXIT_FAILURE;
+	}
+	if (seat == NULL) {
+		fprintf(stderr, "wl_seat not available\n");
+		return EXIT_FAILURE;
+	}
+	if (input_timestamps_manager == NULL) {
+		fprintf(stderr, "zwp_input_timestamps_unstable_manager_v1 not available\n");
+		return EXIT_FAILURE;
+	}
+
+	/* Initialize EGL context */
+
+	struct egl_info *e = calloc(1, sizeof(struct egl_info));
+	e->egl = calloc(1, sizeof(struct wlr_egl));
+	e->width = WIDTH;
+	e->height = HEIGHT;
+
+	wlr_egl_init(e->egl, EGL_PLATFORM_WAYLAND_EXT, display, NULL,
+		WL_SHM_FORMAT_ARGB8888);
+
+	c->egl_info = e;
+
+	/* Create the surface and xdg_toplevels, and set listeners */
+
+	struct wl_surface *surface = wl_compositor_create_surface(compositor);
+	struct xdg_surface *xdg_surface =
+		xdg_wm_base_get_xdg_surface(xdg_wm_base, surface);
+	struct xdg_toplevel *xdg_toplevel = xdg_surface_get_toplevel(xdg_surface);
+
+	xdg_surface_add_listener(xdg_surface, &xdg_surface_listener, e);
+	xdg_toplevel_add_listener(xdg_toplevel, &xdg_toplevel_listener, e);
+
+	/* Create the EGL window and surface */
+
+	wl_surface_commit(surface);
+
+	e->egl_window = wl_egl_window_create(surface, e->width, e->height);
+	e->egl_surface = wlr_egl_create_surface(e->egl, e->egl_window);
+	e->surface = surface;
+
+	wl_display_roundtrip(display);
+
+	paint_pixels(e);
+
+	/* Get the input timestamps and destroy manager */
+
+	if (c->pointer) {
+		c->pointer_input_timestamps =
+			zwp_input_timestamps_manager_v1_get_pointer_timestamps(
+				input_timestamps_manager, c->pointer);
+
+		zwp_input_timestamps_v1_add_listener(c->pointer_input_timestamps,
+			&input_timestamps_listener, &c->pointer_timestamp);
+	}
+
+	if (c->keyboard) {
+		c->keyboard_input_timestamps =
+			zwp_input_timestamps_manager_v1_get_keyboard_timestamps(
+				input_timestamps_manager, c->keyboard);
+
+		zwp_input_timestamps_v1_add_listener(c->keyboard_input_timestamps,
+			&input_timestamps_listener, &c->keyboard_timestamp);
+	}
+
+	zwp_input_timestamps_manager_v1_destroy(input_timestamps_manager);
+
+	/* Run display */
+
+	while (wl_display_dispatch(display) != -1) {
+		/* This space intentionally left blank */
+	}
+
+	return EXIT_SUCCESS;
+}

examples/meson.build

@@ -69,6 +69,10 @@ examples = {
 		'src': 'input-inhibitor.c',
 		'dep': [wayland_client, wayland_cursor, wlr_protos, wlroots],
 	},
+	'input-timestamps': {
+		'src': 'input-timestamps-unstable-v1.c',
+		'dep': [wayland_client, wlr_protos, wlroots],
+	},
 	'gamma-control': {
 		'src': 'gamma-control.c',
 		'dep': [wayland_client, wayland_cursor, wlr_protos, math],