--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/librpg/rpg/battle-indicator.c	Sat Nov 07 16:00:39 2020 +0100
@@ -0,0 +1,134 @@
+/*
+ * battle-indicator.c -- drawable for rendering a hp/mp count usage
+ *
+ * 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 <assert.h>
+#include <math.h>
+#include <stdio.h>
+#include <string.h>
+
+#include <core/color.h>
+#include <core/font.h>
+#include <core/panic.h>
+
+#include <ui/theme.h>
+
+#include "battle-indicator.h"
+
+#define THEME(bti)      ((bti)->theme ? (bti)->theme : theme_default())
+#define STEP            (2)
+#define DELAY           (5)
+
+static inline unsigned int
+inc(int cmp, int tgt)
+{
+	return tgt > cmp ? fmin(cmp + STEP, tgt) : fmax(cmp - STEP, tgt);
+}
+
+static inline bool
+colored(const struct battle_indicator *bti)
+{
+	/* Only check r, g, b and ignore alpha. */
+	return COLOR_R(bti->cur) == COLOR_R(bti->color) &&
+	       COLOR_G(bti->cur) == COLOR_G(bti->color) &&
+	       COLOR_B(bti->cur) == COLOR_B(bti->color);
+}
+
+void
+battle_indicator_start(struct battle_indicator *bti)
+{
+	assert(bti);
+
+	char buf[128];
+	const struct theme *theme = THEME(bti);
+
+	snprintf(buf, sizeof (buf), "%u", bti->amount);
+
+	bti->cur = 0xffffffff;
+	bti->elapsed = 0;
+	bti->alpha = 250;
+	
+	if (!font_render(theme->fonts[THEME_FONT_INTERFACE], &bti->tex[0], buf, bti->cur) ||
+	    !font_render(theme->fonts[THEME_FONT_INTERFACE], &bti->tex[1], buf, 0x000000ff))
+		panic();
+}
+
+bool
+battle_indicator_completed(const struct battle_indicator *bti)
+{
+	assert(battle_indicator_ok(bti));
+
+	return colored(bti) && bti->alpha == 0;
+}
+
+bool
+battle_indicator_ok(const struct battle_indicator *bti)
+{
+	return bti && texture_ok(&bti->tex[0]) && texture_ok(&bti->tex[1]);
+}
+
+bool
+battle_indicator_update(struct battle_indicator *bti, unsigned int ticks)
+{
+	assert(battle_indicator_ok(bti));
+
+	bti->elapsed += ticks;
+
+	if (bti->elapsed > DELAY) {
+		bti->elapsed = 0;
+
+		if (!colored(bti)) {
+			/* Update colors first. */
+			bti->cur = COLOR_HEX(
+			    inc(COLOR_R(bti->cur), COLOR_R(bti->color)),
+			    inc(COLOR_G(bti->cur), COLOR_G(bti->color)),
+			    inc(COLOR_B(bti->cur), COLOR_B(bti->color)),
+			    255
+			);
+
+			texture_set_color_mod(&bti->tex[0], bti->cur);
+		} else {
+			/* Update alpha next. */
+			bti->alpha -= 10;
+
+			texture_set_alpha_mod(&bti->tex[0], bti->alpha);
+			texture_set_alpha_mod(&bti->tex[1], bti->alpha);
+		}
+	}
+
+	return battle_indicator_completed(bti);
+}
+
+void
+battle_indicator_draw(const struct battle_indicator *bti, int x, int y)
+{
+	assert(battle_indicator_ok(bti));
+
+	texture_draw(&bti->tex[1], x + 1, y + 1);
+	texture_draw(&bti->tex[0], x, y);
+}
+
+void
+battle_indicator_finish(struct battle_indicator *bti)
+{
+	assert(bti);
+
+	texture_finish(&bti->tex[0]);
+	texture_finish(&bti->tex[1]);
+
+	memset(bti, 0, sizeof (*bti));
+}