1 files changed, 105 insertions, 0 deletions
diff --git a/libfonts_encode_font_description.c b/libfonts_encode_font_description.c
new file mode 100644
index 0000000..8e0d87a
--- /dev/null
+++ b/libfonts_encode_font_description.c
@@ -0,0 +1,105 @@
+/* See LICENSE file for copyright and license details. */
+#include "libfonts.h"
+#include <ctype.h>
+#include <errno.h>
+#include <string.h>
+
+#define LIST_FIELDS(X)\
+	X(foundry)\
+	X(family_name)\
+	X(weight_name)\
+	X(slant)\
+	X(setwidth_name)\
+	X(add_style_name)\
+	X(pixel_size)\
+	X(point_size)\
+	X(resolution_x)\
+	X(resolution_y)\
+	X(spacing)\
+	X(average_width)\
+	X(charset_registry)\
+	X(charset_encoding)
+
+
+static char *
+encode(char *out, const char *s)
+{
+	for (; *s; s++)
+		*out++ = (*s == '-' ? '~' : *s);
+	return out;
+}
+
+static char *
+encode_range(char *out, const char *s)
+{
+	if (*s == '-') {
+		*out++ = '~';
+		s++;
+	}
+	for (; *s; s++)
+		*out++ = (*s == '-' ? isdigit(s[-1]) ? '_' : '~' : *s);
+	return out;
+}
+
+int
+libfonts_encode_font_description(const struct libfonts_font_description *desc, char out[static 256])
+{
+	size_t n = 1;
+	char *p;
+
+	if (desc->private_font_name) {
+		if (strlen(desc->private_font_name) > 255)
+			goto einval;
+		stpcpy(out, desc->private_font_name);
+		return 0;
+	}
+
+	if (desc->xlfd_version)
+		n += strlen(desc->xlfd_version) + 1;
+
+#define X(F)\
+	if (!desc->F)\
+		goto einval;\
+	n += strlen(desc->F) + 1;
+	LIST_FIELDS(X)
+#undef X
+
+	if (desc->charset_subset)
+		n += strlen(desc->charset_subset) + 2;
+
+	if (desc->unrecognised_fields)
+		n += strlen(desc->unrecognised_fields) + 1;
+
+	if (n > 255)
+		goto einval;
+
+	p = out;
+	if (desc->xlfd_version) {
+		*p++ = '+';
+		p = encode(p, desc->xlfd_version);
+	}
+
+#define X(F)\
+	*p++ = '-';\
+	p = encode(p, desc->F);
+	LIST_FIELDS(X)
+#undef X
+
+	if (desc->charset_subset) {
+		*p++ = '[';
+		p = encode_range(p, desc->charset_subset);
+		*p++ = ']';
+	}
+
+	if (desc->unrecognised_fields) {
+		*p++ = '-';
+		p = stpcpy(p, desc->unrecognised_fields);
+	}
+
+	*p = '\0';
+	return 0;
+
+einval:
+	errno = EINVAL;
+	return -1;
+}