Patch [#34373] Use i18n monospace font in Text editor and Python console

This patch allows Blender to display i18n monospace font in the text
editor and the Python interactive console. Wide characters that occupy
multiple columns such as CJK characters can be displayed correctly.
Furthermore, wrapping, selection, suggestion, cursor drawing, and
syntax highlighting should work.

Also fixes a bug [#34543]: In Text Editor false color in comment on cyrillic

To estimate how many columns each character occupies, this patch uses
wcwidth.c written by Markus Kuhn and distributed under MIT-style license:

  http://www.cl.cam.ac.uk/~mgk25/ucs/wcwidth.c

wcwidth.c is stored in extern/wcwidth and used as a static library.

This patch adds new API to blenfont, blenlib and blenkernel:

BLF_get_unifont_mono()
BLF_free_unifont_mono()
BLF_draw_mono()
BLI_wcwidth()
BLI_wcswidth()
BLI_str_utf8_char_width()
BLI_str_utf8_char_width_safe()
txt_utf8_offset_to_column()
txt_utf8_column_to_offset()

1 files changed, 40 insertions, 6 deletions

diff --git a/source/blender/blenkernel/intern/text.c b/source/blender/blenkernel/intern/text.c
index a155ca47d3c..e229c288a24 100644
--- a/source/blender/blenkernel/intern/text.c
+++ b/source/blender/blenkernel/intern/text.c
@@ -791,6 +791,29 @@ int txt_utf8_index_to_offset(const char *str, int index)
 	return offset;
 }
 
+int txt_utf8_offset_to_column(const char *str, int offset)
+{
+	int column = 0, pos = 0;
+	while (pos < offset) {
+		column += BLI_str_utf8_char_width_safe(str + pos);
+		pos += BLI_str_utf8_size_safe(str + pos);
+	}
+	return column;
+}
+
+int txt_utf8_column_to_offset(const char *str, int column)
+{
+	int offset = 0, pos = 0, col;
+	while (pos < column) {
+		col = BLI_str_utf8_char_width_safe(str + offset);
+		if (pos + col > column)
+			break;
+		offset += BLI_str_utf8_size_safe(str + offset);
+		pos += col;
+	}
+	return offset;
+}
+
 /* returns the real number of characters in string */
 /* not the same as BLI_strlen_utf8, which returns length for wide characters */
 static int txt_utf8_len(const char *src)
@@ -804,6 +827,17 @@ static int txt_utf8_len(const char *src)
 	return len;
 }
 
+static int txt_utf8_width(const char *src)
+{
+	int col = 0;
+
+	for (; *src; src += BLI_str_utf8_size(src)) {
+		col += BLI_str_utf8_char_width(src);
+	}
+
+	return col;
+}
+
 void txt_move_up(Text *text, short sel)
 {
 	TextLine **linep;
@@ -815,10 +849,10 @@ void txt_move_up(Text *text, short sel)
 	if (!*linep) return;
 
 	if ((*linep)->prev) {
-		int index = txt_utf8_offset_to_index((*linep)->line, *charp);
+		int column = txt_utf8_offset_to_column((*linep)->line, *charp);
 		*linep = (*linep)->prev;
-		if (index > txt_utf8_len((*linep)->line)) *charp = (*linep)->len;
-		else *charp = txt_utf8_index_to_offset((*linep)->line, index);
+		if (column > txt_utf8_width((*linep)->line)) *charp = (*linep)->len;
+		else *charp = txt_utf8_column_to_offset((*linep)->line, column);
 		
 	}
 	else {
@@ -839,10 +873,10 @@ void txt_move_down(Text *text, short sel)
 	if (!*linep) return;
 
 	if ((*linep)->next) {
-		int index = txt_utf8_offset_to_index((*linep)->line, *charp);
+		int column = txt_utf8_offset_to_column((*linep)->line, *charp);
 		*linep = (*linep)->next;
-		if (index > txt_utf8_len((*linep)->line)) *charp = (*linep)->len;
-		else *charp = txt_utf8_index_to_offset((*linep)->line, index);
+		if (column > txt_utf8_width((*linep)->line)) *charp = (*linep)->len;
+		else *charp = txt_utf8_column_to_offset((*linep)->line, column);
 	}
 	else {
 		txt_move_eol(text, sel);