--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/examples/example-ui/example-ui.c	Sun Oct 09 13:53:33 2022 +0200
@@ -0,0 +1,288 @@
+/*
+ * example-action.c -- example on how to use automatic actions
+ *
+ * Copyright (c) 2020-2022 David Demelier <markand@malikania.fr>
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include <core/core.h>
+#include <core/event.h>
+#include <core/game.h>
+#include <core/maths.h>
+#include <core/panic.h>
+#include <core/painter.h>
+#include <core/state.h>
+#include <core/sys.h>
+#include <core/util.h>
+#include <core/window.h>
+
+#include <ui/align.h>
+#include <ui/button.h>
+#include <ui/checkbox.h>
+#include <ui/frame.h>
+#include <ui/label.h>
+#include <ui/theme.h>
+#include <ui/ui.h>
+
+#define W               (1280)
+#define H               (720)
+
+#define FRAME_ORIGIN_X  (10)
+#define FRAME_ORIGIN_Y  (10)
+#define FRAME_WIDTH     (400)
+#define FRAME_HEIGHT    (200)
+
+#define HEADER_HEIGHT   (32)
+
+#define ELEMENT_HEIGHT  (20)
+
+/*
+ * We design a basic UI like this.
+ *
+ *                    FRAME_WIDTH
+ * +---------------------------------------------+--
+ * | Title                                       | | HEADER_HEIGHT
+ * +---------------------------------------------+--
+ * | [x] Auto save                               |
+ * |                                             |
+ * |                                             |
+ * |                                    [ Quit ] |
+ * +---------------------------------------------+
+ */
+static struct {
+	struct {
+		int active;
+		int x;
+		int y;
+	} motion;
+
+	struct {
+		struct frame frame;
+	} panel;
+
+	struct {
+		struct label label;
+	} header;
+
+	struct {
+		struct checkbox cb;
+		struct label label;
+	} autosave;
+
+	struct {
+		struct button button;
+	} quit;
+} ui = {
+	.panel = {
+		.frame = {
+			.x = FRAME_ORIGIN_X,
+			.y = FRAME_ORIGIN_Y,
+			.w = FRAME_WIDTH,
+			.h = FRAME_HEIGHT
+		}
+	},
+	.header = {
+		.label = {
+			.text = "Preferences",
+			.x = FRAME_ORIGIN_X,
+			.y = FRAME_ORIGIN_Y,
+			.flags = LABEL_FLAGS_SHADOW,
+		}
+	},
+	.autosave = {
+		.cb = {
+			.w = ELEMENT_HEIGHT,
+			.h = ELEMENT_HEIGHT
+		},
+		.label = {
+			.text = "Auto save game",
+			.flags = LABEL_FLAGS_SHADOW,
+		}
+	},
+	.quit = {
+		.button = {
+			.text = "Quit",
+			.h = ELEMENT_HEIGHT
+		}
+	}
+};
+
+static struct state *states[1];
+
+static void
+init(void)
+{
+	if (core_init("fr.malikania", "example-ui") < 0 || ui_init() < 0)
+		panic();
+	if (window_open("Example - UI", W, H) < 0)
+		panic();
+}
+
+static void
+resize_header(void)
+{
+	struct frame *f = &ui.panel.frame;
+	struct label *l = &ui.header.label;
+	unsigned int w, h;
+
+	/* Header. */
+	label_query(l, &w, &h);
+	align(ALIGN_LEFT, &l->x, &l->y, w, h, f->x, f->y, f->w, HEADER_HEIGHT);
+
+	l->x += theme_default()->padding;
+}
+
+static void
+resize_autosave(void)
+{
+	unsigned int padding = theme_default()->padding;
+	struct frame *f = &ui.panel.frame;
+	struct checkbox *c = &ui.autosave.cb;
+	struct label *l = &ui.autosave.label;
+
+	c->x = f->x + padding;
+	c->y = f->y + HEADER_HEIGHT + padding;
+
+	l->x = c->x + c->w + padding;
+	l->y = c->y;
+}
+
+static void
+resize_button(void)
+{
+	unsigned int padding = theme_default()->padding;
+	struct frame *f = &ui.panel.frame;
+	struct button *b = &ui.quit.button;
+
+	/* Button. */
+	b->w = f->w / 4;
+
+	align(ALIGN_BOTTOM_RIGHT, &b->x, &b->y, b->w, b->h,
+	    f->x, f->y, f->w, f->h);
+
+	b->x -= padding;
+	b->y -= padding;
+}
+
+static void
+resize(void)
+{
+	resize_header();
+	resize_autosave();
+	resize_button();
+}
+
+static int
+headerclick(int x, int y)
+{
+	return maths_is_boxed(
+	    ui.panel.frame.x,
+	    ui.panel.frame.y,
+	    ui.panel.frame.w,
+	    HEADER_HEIGHT,
+	    x,
+	    y
+	);
+}
+
+static void
+handle(struct state *st, const union event *ev)
+{
+	(void)st;
+
+	switch (ev->type) {
+	case EVENT_QUIT:
+		game_quit();
+		break;
+	case EVENT_MOUSE:
+		if (ui.motion.active) {
+			ui.panel.frame.x += ev->mouse.x - ui.motion.x;
+			ui.panel.frame.y += ev->mouse.y - ui.motion.y;
+			ui.motion.x = ev->mouse.x;
+			ui.motion.y = ev->mouse.y;
+			resize();
+		}
+		break;
+	case EVENT_CLICKDOWN:
+		if (headerclick(ev->click.x, ev->click.y)) {
+			ui.motion.active = 1;
+			ui.motion.x = ev->click.x;
+			ui.motion.y = ev->click.y;
+			window_set_cursor(WINDOW_CURSOR_SIZE);
+		}
+		break;
+	case EVENT_CLICKUP:
+		ui.motion.active = 0;
+		window_set_cursor(WINDOW_CURSOR_ARROW);
+		break;
+	default:
+		break;
+	}
+
+	checkbox_handle(&ui.autosave.cb, ev);
+
+	if (button_handle(&ui.quit.button, ev))
+		game_quit();
+}
+
+static void
+draw(struct state *st)
+{
+	(void)st;
+
+	painter_set_color(0xffffffff);
+	painter_clear();
+	frame_draw(&ui.panel.frame);
+	label_draw(&ui.header.label);
+	checkbox_draw(&ui.autosave.cb);
+	label_draw(&ui.autosave.label);
+	button_draw(&ui.quit.button);
+	painter_present();
+}
+
+static void
+run(void)
+{
+	struct state state = {
+		.handle = handle,
+		.draw = draw
+	};
+
+	resize();
+
+	game_init(states, UTIL_SIZE(states));
+	game_push(&state);
+	game_loop();
+}
+
+static void
+quit(void)
+{
+	window_finish();
+	ui_finish();
+	core_finish();
+}
+
+int
+main(int argc, char **argv)
+{
+	(void)argc;
+	(void)argv;
+
+	init();
+	run();
+	quit();
+
+	return 0;
+}