examples: introduce quads example

This examples uses `wlr_render_quad_with_matrix` to render coloured
squares on the screen, and uses the rotation to make them spin on their
middle.

examples/meson.build

@@ -49,6 +49,9 @@ compositors = {
 		'src': 'fullscreen-shell.c',
 		'proto': ['fullscreen-shell-unstable-v1'],
 	},
+	'quads': {
+		'src': 'quads.c',
+	},
 }
 
 clients = {

examples/quads.c

@@ -0,0 +1,212 @@
+#define _XOPEN_SOURCE 600
+#include <getopt.h>
+#include <math.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <strings.h>
+#include <time.h>
+#include <unistd.h>
+#include <wayland-server-core.h>
+#include <wlr/backend.h>
+#include <wlr/render/wlr_renderer.h>
+#include <wlr/types/wlr_keyboard.h>
+#include <wlr/types/wlr_output.h>
+#include <wlr/types/wlr_input_device.h>
+#include <wlr/types/wlr_matrix.h>
+#include <wlr/util/log.h>
+#include <xkbcommon/xkbcommon.h>
+
+struct sample_state {
+	struct wl_display *display;
+	struct wl_listener new_output;
+	struct wl_listener new_input;
+	struct timespec last_frame;
+	struct wlr_renderer *renderer;
+	struct wl_list outputs;
+};
+
+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;
+};
+
+static void output_frame_notify(struct wl_listener *listener, void *data) {
+	struct sample_output *sample_output = wl_container_of(listener, sample_output, frame);
+	struct sample_state *sample = sample_output->sample;
+	struct wlr_output *wlr_output = sample_output->output;
+	struct timespec now;
+	clock_gettime(CLOCK_MONOTONIC, &now);
+
+	int32_t width, height;
+	wlr_output_effective_resolution(wlr_output, &width, &height);
+
+	wlr_output_attach_render(wlr_output, NULL);
+	wlr_renderer_begin(sample->renderer, wlr_output->width, wlr_output->height);
+	wlr_renderer_clear(sample->renderer, (float[]){0.25f, 0.25f, 0.25f, 1});
+
+	static float rotation = 0.f;
+	for (int y = -128; y < height; y += 128) {
+		for (int x = -128; x < width; x += 128) {
+			struct wlr_box box = {
+				.x = x,
+				.y = y,
+				.width = 128,
+				.height = 128,
+			};
+
+			float color[] = {
+				255.f / x,
+				255.f / y,
+				255.f / (x + y),
+				1.f
+			};
+
+			float matrix[9];
+			wlr_matrix_project_box(matrix, &box, WL_OUTPUT_TRANSFORM_NORMAL,
+					rotation, wlr_output->transform_matrix);
+
+			wlr_render_quad_with_matrix(sample->renderer, color, matrix);
+		}
+	}
+
+	wlr_renderer_end(sample->renderer);
+	wlr_output_commit(wlr_output);
+
+	//TODO rotate with a delta time
+	rotation += 0.05;
+	if (rotation > 2 * M_PI) {
+		rotation = 0.f;
+	}
+
+	sample->last_frame = now;
+}
+
+static void output_remove_notify(struct wl_listener *listener, void *data) {
+	struct sample_output *sample_output = wl_container_of(listener, sample_output, destroy);
+	wl_list_remove(&sample_output->frame.link);
+	wl_list_remove(&sample_output->destroy.link);
+	free(sample_output);
+}
+
+static 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));
+
+	struct wlr_output_mode *mode = wlr_output_preferred_mode(output);
+	if (mode != NULL) {
+		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;
+	wl_list_insert(&sample->outputs, &sample_output->link);
+
+	wlr_output_commit(output);
+}
+
+static 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);
+		}
+	}
+}
+
+static 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);
+}
+
+static 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_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, NULL,
+			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;
+	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 = {
+		.display = display,
+	};
+	wl_list_init(&state.outputs);
+
+	struct wlr_backend *wlr = wlr_backend_autocreate(display);
+	if (!wlr) {
+		exit(1);
+	}
+
+	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);
+
+	state.renderer = wlr_backend_get_renderer(wlr);
+	if (!state.renderer) {
+		wlr_log(WLR_ERROR, "Could not start compositor, OOM");
+		wlr_backend_destroy(wlr);
+		exit(EXIT_FAILURE);
+	}
+
+	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);
+}