text: #define _POSIX_C_SOURCE 200112L
  #include <assert.h>
  #include <GLES2/gl2.h>
  #include <math.h>
  #include <stdio.h>
  #include <stdlib.h>
  #include <string.h>
  #include <time.h>
  #include <unistd.h>
  #include <wayland-server-protocol.h>
  #include <wayland-server.h>
  #include <wlr/backend.h>
  #include <wlr/backend/session.h>
  #include <wlr/render/gles2.h>
  #include <wlr/render/wlr_renderer.h>
  #include <wlr/types/wlr_cursor.h>
  #include <wlr/types/wlr_keyboard.h>
  #include <wlr/types/wlr_list.h>
  #include <wlr/types/wlr_matrix.h>
  #include <wlr/types/wlr_output_layout.h>
  #include <wlr/util/log.h>
  #include <wlr/xcursor.h>
  #include <xkbcommon/xkbcommon.h>
  
  struct sample_state {
  	struct wl_display *display;
  	struct wlr_xcursor *xcursor;
  	float default_color[4];
  	float clear_color[4];
  	struct wlr_output_layout *layout;
  	struct wl_list cursors; // sample_cursor::link
  	struct wl_list pointers; // sample_pointer::link
  	struct wl_list outputs; // sample_output::link
  	struct timespec last_frame;
  	struct wl_listener new_output;
  	struct wl_listener new_input;
  };
  
  struct sample_cursor {
  	struct sample_state *sample;
  	struct wlr_input_device *device;
  	struct wlr_cursor *cursor;
  	struct wl_list link;
  
  	struct wl_listener cursor_motion;
  	struct wl_listener cursor_motion_absolute;
  	struct wl_listener cursor_button;
  	struct wl_listener cursor_axis;
  	struct wl_listener destroy;
  };
  
  struct sample_pointer {
  	struct wlr_input_device *device;
  	struct wl_list link;
  };
  
  struct sample_output {
  	struct sample_state *sample;
  	struct wlr_output *output;
  	struct wl_listener frame;
  	struct wl_listener destroy;
  	struct wl_list link;
  };
  
  struct sample_keyboard {
  	struct sample_state *sample;
  	struct wlr_input_device *device;
  	struct wl_listener key;
  	struct wl_listener destroy;
  };
  
  void configure_cursor(struct wlr_cursor *cursor, struct wlr_input_device *device,
  		 struct sample_state *sample) {
  	struct sample_output *output;
  	wlr_log(WLR_ERROR, "Configuring cursor %p for device %p", cursor, device);
  
  	// reset mappings
  	wlr_cursor_map_to_output(cursor, NULL);
  	wlr_cursor_detach_input_device(cursor, device);
  	wlr_cursor_map_input_to_output(cursor, device, NULL);
  
  	wlr_cursor_attach_input_device(cursor, device);
  
  	// configure device to output mappings
  	wl_list_for_each(output, &sample->outputs, link) {
  		wlr_cursor_map_to_output(cursor, output->output);
  
  		wlr_cursor_map_input_to_output(cursor, device, output->output);
  	}
  }
  
  void output_frame_notify(struct wl_listener *listener, void *data) {
  	struct sample_output *output = wl_container_of(listener, output, frame);
  	struct sample_state *sample = output->sample;
  	struct wlr_output *wlr_output = output->output;
  
  	wlr_output_attach_render(wlr_output, NULL);
  
  	glClearColor(sample->clear_color[0], sample->clear_color[1],
  		sample->clear_color[2], sample->clear_color[3]);
  	glClear(GL_COLOR_BUFFER_BIT);
  
  	wlr_output_render_software_cursors(wlr_output, NULL);
  	wlr_output_commit(wlr_output);
  }
  
  static void handle_cursor_motion(struct wl_listener *listener, void *data) {
  	struct sample_cursor *cursor =
  		wl_container_of(listener, cursor, cursor_motion);
  	struct wlr_event_pointer_motion *event = data;
  	wlr_cursor_move(cursor->cursor, event->device, event->delta_x,
  		event->delta_y);
  }
  
  static void handle_cursor_motion_absolute(struct wl_listener *listener,
  		void *data) {
  	struct sample_cursor *cursor =
  		wl_container_of(listener, cursor, cursor_motion_absolute);
  	struct wlr_event_pointer_motion_absolute *event = data;
  	wlr_cursor_warp_absolute(cursor->cursor, event->device, event->x, event->y);
  }
  
  static void cursor_destroy(struct sample_cursor *cursor) {
  	wl_list_remove(&cursor->link);
  	wl_list_remove(&cursor->cursor_motion.link);
  	wl_list_remove(&cursor->cursor_motion_absolute.link);
  	wlr_cursor_destroy(cursor->cursor);
  	free(cursor);
  }
  
  void input_remove_notify(struct wl_listener *listener, void *data) {
  	struct wlr_input_device *device = data;
  	struct sample_cursor *sample_cursor = wl_container_of(listener, sample_cursor, destroy);
  	struct sample_state *sample = sample_cursor->sample;
  	struct sample_cursor *cursor;
  	wl_list_for_each(cursor, &sample->cursors, link) {
  		if (cursor->device == device) {
  			cursor_destroy(cursor);
  			break;
  		}
  	}
  	struct sample_pointer *pointer;
  	wl_list_for_each(pointer, &sample->pointers, link) {
  		if (pointer->device == device) {
  			free(pointer);
  			break;
  		}
  	}
  }
  
  void output_remove_notify(struct wl_listener *listener, void *data) {
  	struct sample_output *sample_output = wl_container_of(listener, sample_output, destroy);
  	struct sample_state *sample = sample_output->sample;
  	wl_list_remove(&sample_output->frame.link);
  	wl_list_remove(&sample_output->destroy.link);
  	wl_list_remove(&sample_output->link);
  	free(sample_output);
  
  	struct sample_cursor *cursor;
  	wl_list_for_each(cursor, &sample->cursors, link) {
  		configure_cursor(cursor->cursor, cursor->device, sample);
  	}
  }
  
  void new_output_notify(struct wl_listener *listener, void *data) {
  	struct wlr_output *output = data;
  	struct sample_state *sample = wl_container_of(listener, sample, new_output);
  	struct sample_output *sample_output = calloc(1, sizeof(struct sample_output));
  	if (!wl_list_empty(&output->modes)) {
  		struct wlr_output_mode *mode = wl_container_of(output->modes.prev, mode, link);
  		wlr_output_set_mode(output, mode);
  	}
  	sample_output->output = output;
  	sample_output->sample = sample;
  	wl_signal_add(&output->events.frame, &sample_output->frame);
  	sample_output->frame.notify = output_frame_notify;
  	wl_signal_add(&output->events.destroy, &sample_output->destroy);
  	sample_output->destroy.notify = output_remove_notify;
  
  	wlr_output_layout_add_auto(sample->layout, output);
  
  
  	struct sample_cursor *cursor;
  	wl_list_for_each(cursor, &sample->cursors, link) {
  		configure_cursor(cursor->cursor, cursor->device, sample);
  
  		struct wlr_xcursor_image *image = sample->xcursor->images[0];
  		wlr_cursor_set_image(cursor->cursor, image->buffer, image->width * 4,
  			image->width, image->height, image->hotspot_x, image->hotspot_y, 0);
  
  		wlr_cursor_warp(cursor->cursor, NULL, cursor->cursor->x,
  			cursor->cursor->y);
  	}
  	wl_list_insert(&sample->outputs, &sample_output->link);
  }
  
  void keyboard_key_notify(struct wl_listener *listener, void *data) {
  	struct sample_keyboard *keyboard = wl_container_of(listener, keyboard, key);
  	struct sample_state *sample = keyboard->sample;
  	struct wlr_event_keyboard_key *event = data;
  	uint32_t keycode = event->keycode + 8;
  	const xkb_keysym_t *syms;
  	int nsyms = xkb_state_key_get_syms(keyboard->device->keyboard->xkb_state,
  			keycode, &syms);
  	for (int i = 0; i < nsyms; i++) {
  		xkb_keysym_t sym = syms[i];
  		if (sym == XKB_KEY_Escape) {
  			wl_display_terminate(sample->display);
  		}
  	}
  }
  
  void keyboard_destroy_notify(struct wl_listener *listener, void *data) {
  	struct sample_keyboard *keyboard = wl_container_of(listener, keyboard, destroy);
  	wl_list_remove(&keyboard->destroy.link);
  	wl_list_remove(&keyboard->key.link);
  	free(keyboard);
  }
  
  void new_input_notify(struct wl_listener *listener, void *data) {
  	struct wlr_input_device *device = data;
  	struct sample_state *sample = wl_container_of(listener, sample, new_input);
  	switch (device->type) {
  	case WLR_INPUT_DEVICE_KEYBOARD:;
  		struct sample_keyboard *keyboard = calloc(1, sizeof(struct sample_keyboard));
  		keyboard->device = device;
  		keyboard->sample = sample;
  		wl_signal_add(&device->events.destroy, &keyboard->destroy);
  		keyboard->destroy.notify = keyboard_destroy_notify;
  		wl_signal_add(&device->keyboard->events.key, &keyboard->key);
  		keyboard->key.notify = keyboard_key_notify;
  		struct xkb_rule_names rules = { 0 };
  		rules.rules = getenv("XKB_DEFAULT_RULES");
  		rules.model = getenv("XKB_DEFAULT_MODEL");
  		rules.layout = getenv("XKB_DEFAULT_LAYOUT");
  		rules.variant = getenv("XKB_DEFAULT_VARIANT");
  		rules.options = getenv("XKB_DEFAULT_OPTIONS");
  		struct xkb_context *context = xkb_context_new(XKB_CONTEXT_NO_FLAGS);
  		if (!context) {
  			wlr_log(WLR_ERROR, "Failed to create XKB context");
  			exit(1);
  		}
  		struct xkb_keymap *keymap = xkb_map_new_from_names(context, &rules,
  			XKB_KEYMAP_COMPILE_NO_FLAGS);
  		if (!keymap) {
  			wlr_log(WLR_ERROR, "Failed to create XKB keymap");
  			exit(1);
  		}
  		wlr_keyboard_set_keymap(device->keyboard, keymap);
  		xkb_keymap_unref(keymap);
  		xkb_context_unref(context);
  		break;
  	case WLR_INPUT_DEVICE_POINTER:;
  		struct sample_cursor *cursor = calloc(1, sizeof(struct sample_cursor));
  		struct sample_pointer *pointer = calloc(1, sizeof(struct sample_pointer));
  		pointer->device = device;
  		cursor->sample = sample;
  		cursor->device = device;
  
  		cursor->cursor = wlr_cursor_create();
  
  		wlr_cursor_attach_output_layout(cursor->cursor, sample->layout);
  
  		wl_signal_add(&cursor->cursor->events.motion, &cursor->cursor_motion);
  		cursor->cursor_motion.notify = handle_cursor_motion;
  		wl_signal_add(&cursor->cursor->events.motion_absolute,
  			&cursor->cursor_motion_absolute);
  		cursor->cursor_motion_absolute.notify = handle_cursor_motion_absolute;
  
  		wlr_cursor_attach_input_device(cursor->cursor, device);
  		configure_cursor(cursor->cursor, device, sample);
  
  		struct wlr_xcursor_image *image = sample->xcursor->images[0];
  		wlr_cursor_set_image(cursor->cursor, image->buffer, image->width * 4,
  			image->width, image->height, image->hotspot_x, image->hotspot_y, 0);
  
  		wl_list_insert(&sample->cursors, &cursor->link);
  		wl_list_insert(&sample->pointers, &pointer->link);
  		break;
  	default:
  		break;
  	}
  }
  
  int main(int argc, char *argv[]) {
  	wlr_log_init(WLR_DEBUG, NULL);
  	struct wl_display *display = wl_display_create();
  	struct sample_state state = {
  		.default_color = { 0.25f, 0.25f, 0.25f, 1 },
  		.clear_color = { 0.25f, 0.25f, 0.25f, 1 },
  		.display = display,
  	};
  	struct wlr_backend *wlr = wlr_backend_autocreate(display, NULL);
  	if (!wlr) {
  		exit(1);
  	}
  	wl_list_init(&state.cursors);
  	wl_list_init(&state.pointers);
  	wl_list_init(&state.outputs);
  
  	state.layout = wlr_output_layout_create();
  
  	wl_signal_add(&wlr->events.new_output, &state.new_output);
  	state.new_output.notify = new_output_notify;
  	wl_signal_add(&wlr->events.new_input, &state.new_input);
  	state.new_input.notify = new_input_notify;
  
  	clock_gettime(CLOCK_MONOTONIC, &state.last_frame);
  
  	struct wlr_xcursor_theme *theme = wlr_xcursor_theme_load("default", 16);
  	if (!theme) {
  		wlr_log(WLR_ERROR, "Failed to load cursor theme");
  		return 1;
  	}
  	state.xcursor = wlr_xcursor_theme_get_cursor(theme, "left_ptr");
  	if (!state.xcursor) {
  		wlr_log(WLR_ERROR, "Failed to load left_ptr cursor");
  		return 1;
  	}
  
  	if (!wlr_backend_start(wlr)) {
  		wlr_log(WLR_ERROR, "Failed to start backend");
  		wlr_backend_destroy(wlr);
  		exit(1);
  	}
  	wl_display_run(display);
  	wl_display_destroy(display);
  
  	struct sample_cursor *cursor, *tmp_cursor;
  	wl_list_for_each_safe(cursor, tmp_cursor, &state.cursors, link) {
  		cursor_destroy(cursor);
  	}
  
  	struct sample_pointer *pointer, *tmp_pointer;
  	wl_list_for_each_safe(pointer, tmp_pointer, &state.pointers, link) {
  		free(pointer);
  	}
  
  	wlr_xcursor_theme_destroy(theme);
  	wlr_output_layout_destroy(state.layout);
  }
  