altos/draw: Add ao_text_width

Computes the total advance of the given string, not the width of the
resulting ink.

Signed-off-by: Keith Packard <keithp@keithp.com>

diff --git a/src/draw/ao_draw.h b/src/draw/ao_draw.h
index 7f1a413cd980be8ed87d10b0dcb9fce261194996..96e334981bcf91825b564deb77e48ebca5dad558 100644 (file)
--- a/src/draw/ao_draw.h
+++ b/src/draw/ao_draw.h
@@ -103,6 +103,14 @@ struct ao_glyph_metrics {
        int8_t  advance;
 };
 
+struct ao_text_metrics {
+       int16_t width;
+       int16_t height;
+       int16_t x_off;
+       int16_t y_off;
+       int16_t advance;
+};
+
 struct ao_font {
        const uint8_t   *bytes;
        const uint16_t  *pos;
@@ -169,6 +177,10 @@ ao_text(struct ao_bitmap   *dst,
        uint32_t                fill,
        uint8_t                 rop);
 
+int16_t
+ao_text_width(const struct ao_font     *font,
+             const char                *string);
+
 void
 ao_logo_poly(struct ao_bitmap          *dst,
             const struct ao_transform  *transform,

diff --git a/src/draw/ao_text_width.c b/src/draw/ao_text_width.c
new file mode 100644 (file)
index 0000000..9f08bd0
--- /dev/null
+++ b/src/draw/ao_text_width.c
@@ -0,0 +1,40 @@
+/*
+ * Copyright © 2024 Keith Packard <keithp@keithp.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
+ */
+
+#include <ao_draw.h>
+#include <ao_draw_int.h>
+#include "ao_font.h"
+#include <string.h>
+#include <stdio.h>
+
+int16_t
+ao_text_width(const struct ao_font     *font,
+             const char                *string)
+{
+       char            c;
+       int16_t         x = 0;
+
+       while ((c = *string++)) {
+               if (font->metrics) {
+                       x += font->metrics[(uint8_t) c].advance;
+               } else {
+                       x += font->max_width;
+               }
+       }
+       return x;
+}