fosphor/gl_font: Introduce new glf_printf convenience function

This avoids having to do a sprintf then a draw_str myself every time.

Signed-off-by: Sylvain Munaut <tnt@246tNt.com>

lib/fosphor/gl_font.c

@@ -29,6 +29,7 @@
 
 #include <errno.h>
 #include <math.h>
+#include <stdarg.h>
 #include <stdint.h>
 
 #include <ft2build.h>
@@ -407,6 +408,46 @@ glf_draw_str(const struct gl_font *glf,
 	free(data);
 }
 
+void
+glf_printf(const struct gl_font *glf,
+           float x, enum glf_align x_align,
+           float y, enum glf_align y_align,
+           const char *fmt, ...)
+{
+	va_list va1, va2;
+	char *buf;
+	char static_buf[128];
+	int l;
+
+	/* Grab 2 copies of the arguments */
+	va_start(va1, fmt);
+	va_copy(va2, va1);
+
+	/* Print to buffer (try a stack, fallback to heap if needed) */
+	l = vsnprintf(static_buf, sizeof(static_buf), fmt, va1);
+
+	if (l >= sizeof(static_buf)) {
+		buf = malloc(l + 1);
+		if (!buf)
+			goto error;
+
+		vsnprintf(buf, l, fmt, va2);
+	} else {
+		buf = static_buf;
+	}
+
+	/* Draw it */
+	glf_draw_str(glf, x, x_align, y, y_align, buf);
+
+	/* Release everything */
+error:
+	va_end(va2);
+	va_end(va1);
+
+	if (buf && buf != static_buf)
+		free(buf);
+}
+
 void
 glf_begin(const struct gl_font *glf, float fg_color[3])
 {

lib/fosphor/gl_font.h

@@ -55,6 +55,11 @@ void glf_draw_str(const struct gl_font *glf,
                   float y, enum glf_align y_align,
                   const char *str);
 
+void glf_printf(const struct gl_font *glf,
+                float x, enum glf_align x_align,
+                float y, enum glf_align y_align,
+                const char *fmt, ...) __attribute__((format(printf, 6, 7)));
+
 void glf_begin(const struct gl_font *glf, float fg_color[3]);
 void glf_end(void);