--- a/examples/CMakeLists.txt	Wed Oct 14 14:52:26 2020 +0200
+++ b/examples/CMakeLists.txt	Wed Oct 14 16:40:34 2020 +0200
@@ -29,6 +29,12 @@
 )
 
 molko_define_executable(
+	TARGET example-font
+	SOURCES example-font.c
+	LIBRARIES libcore
+)
+
+molko_define_executable(
 	TARGET example-inventory
 	SOURCES example-inventory
 	ASSETS

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/examples/example-font.c	Wed Oct 14 16:40:34 2020 +0200
@@ -0,0 +1,136 @@
+/*
+ * example-font.c -- show how to use fonts
+ *
+ * Copyright (c) 2020 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/clock.h>
+#include <core/event.h>
+#include <core/font.h>
+#include <core/painter.h>
+#include <core/panic.h>
+#include <core/sys.h>
+#include <core/texture.h>
+#include <core/theme.h>
+#include <core/util.h>
+#include <core/window.h>
+
+#define W       (1280)
+#define H       (720)
+
+/* Friendly taken from: https://lospec.com/palette-list/apollo */
+static const unsigned long colors[] = {
+	0x3c5e8bff,     /* Blue. */
+	0x468232ff,     /* Green. */
+	0xad7757ff,     /* Light brown. */
+	0x884b2bff,     /* Brown. */
+	0x752438ff,     /* Red. */
+	0x7a367bff,     /* Magenta. */
+	0x151d28ff,     /* Dark */
+	0xc7cfccff,     /* Christian Grey. */
+};
+
+static void
+init(void)
+{
+	if (!sys_init() ||
+	    !window_init("Example - Font", W, H) ||
+	    !theme_init())
+		panic();
+}
+
+static void
+run(void)
+{
+	struct clock clock = {0};
+	struct font *font = theme_default()->fonts[THEME_FONT_INTERFACE];
+	int ci = 0;
+	enum font_style style = font->style;
+
+	clock_start(&clock);
+
+	for (;;) {
+		struct texture tex;
+		union event ev;
+		unsigned int elapsed = clock_elapsed(&clock);
+
+		clock_start(&clock);
+
+		while (event_poll(&ev)) {
+			switch (ev.type) {
+			case EVENT_KEYDOWN:
+				switch (ev.key.key) {
+				case KEY_LEFT:
+					if (ci > 0)
+						ci--;
+					break;
+				case KEY_RIGHT:
+					if ((size_t)ci < NELEM(colors))
+						ci++;
+					break;
+				case KEY_SPACE:
+					if (style == FONT_STYLE_ANTIALIASED)
+						style = FONT_STYLE_NONE;
+					else
+						style = FONT_STYLE_ANTIALIASED;
+				default:
+					break;
+				}
+				break;
+			case EVENT_QUIT:
+				return;
+			default:
+				break;
+			}
+		}
+
+		painter_set_color(0xffffffff);
+		painter_clear();
+
+		font->color = colors[ci];
+		font->style = style;
+
+		if (!font_render(font, &tex, "Example of text. Use <Left>/<Right> to change color and <Space> to toggle antialiasing."))
+			panic();
+
+		texture_draw(&tex, 10, 10);
+		painter_present();
+		texture_finish(&tex);
+
+		if ((elapsed = clock_elapsed(&clock)) < 20)
+			delay(20 - elapsed);
+	}
+}
+
+static void
+quit(void)
+{
+	theme_finish();
+	window_finish();
+	sys_finish();
+}
+
+int
+main(int argc, char **argv)
+{
+	(void)argc;
+	(void)argv;
+
+	init();
+	run();
+	quit();
+
+	return 0;
+}

--- a/libcore/core/font.c	Wed Oct 14 14:52:26 2020 +0200
+++ b/libcore/core/font.c	Wed Oct 14 16:40:34 2020 +0200
@@ -17,8 +17,6 @@
  */
 
 #include <assert.h>
-#include <stdbool.h>
-#include <stdio.h>
 
 #include <SDL_ttf.h>
 
@@ -67,7 +65,7 @@
 bool
 font_render(struct font *font, struct texture *tex, const char *text)
 {
-	assert(font);
+	assert(font_ok(font));
 	assert(text);
 
 	SDL_Color fg = {
@@ -97,11 +95,23 @@
 unsigned int
 font_height(const struct font *font)
 {
-	assert(font);
+	assert(font_ok(font));
 
 	return TTF_FontHeight(font->handle);
 }
 
+bool
+font_box(const struct font *font, const char *text, unsigned int *w, unsigned int *h)
+{
+	assert(font_ok(font));
+	assert(text);
+
+	if (TTF_SizeUTF8(font->handle, text, (int *)w, (int *)h) != 0)
+		return error_sdl();
+
+	return true;
+}
+
 void
 font_finish(struct font *font)
 {
@@ -109,4 +119,6 @@
 
 	if (font->handle)
 		TTF_CloseFont(font->handle);
+
+	memset(font, 0, sizeof (*font));
 }

--- a/libcore/core/font.h	Wed Oct 14 14:52:26 2020 +0200
+++ b/libcore/core/font.h	Wed Oct 14 16:40:34 2020 +0200
@@ -44,7 +44,7 @@
 struct font {
 	enum font_style style;          /*!< (RW) Style for rendering. */
 	unsigned long color;            /*!< (RW) Color for rendering. */
-	void *handle;                   /*!< (RO) Native handle. */
+	void *handle;                   /*!< (PV) Native handle. */
 };
 
 /**
@@ -91,7 +91,7 @@
  * This function use the current color/style and other properties in the font
  * to render the texture.
  *
- * \pre font != NULL
+ * \pre font_ok(font)
  * \pre tex != NULL
  * \param font the font to use
  * \param tex the texture to generate
@@ -104,7 +104,7 @@
 /**
  * Get the maximum height for all glyphs.
  *
- * \pre font != NULL
+ * \pre font_ok(font)
  * \param font the font handle
  * \return the height in pixels
  */
@@ -112,6 +112,20 @@
 font_height(const struct font *font);
 
 /**
+ * Compute the text size required with this font.
+ *
+ * \pre font_ok(font)
+ * \pre text != NULL
+ * \param font the font object
+ * \param text the UTF-8 text
+ * \param w pointer to width (may be NULL)
+ * \param h pointer to height (may be NULL)
+ * \return false in case of error and pointers to w and h are left unmodified
+ */
+bool
+font_box(const struct font *font, const char *text, unsigned int *w, unsigned int *h);
+
+/**
  * Close the font.
  *
  * \pre font != NULL