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, 34 insertions, 0 deletions

diff --git a/source/blender/blenfont/intern/blf_font.c b/source/blender/blenfont/intern/blf_font.c
index 1900efa2dbc..f2c36475870 100644
--- a/source/blender/blenfont/intern/blf_font.c
+++ b/source/blender/blenfont/intern/blf_font.c
@@ -219,6 +219,40 @@ void blf_font_draw_ascii(FontBLF *font, const char *str, size_t len)
 	}
 }
 
+/* use fixed column width, but an utf8 character may occupy multiple columns */
+int blf_font_draw_mono(FontBLF *font, const char *str, size_t len, int cwidth)
+{
+	unsigned int c;
+	GlyphBLF *g;
+	int col, columns = 0;
+	int pen_x = 0, pen_y = 0;
+	size_t i = 0;
+	GlyphBLF **glyph_ascii_table = font->glyph_cache->glyph_ascii_table;
+
+	blf_font_ensure_ascii_table(font);
+
+	while ((i < len) && str[i]) {
+		BLF_UTF8_NEXT_FAST(font, g, str, i, c, glyph_ascii_table);
+
+		if (c == BLI_UTF8_ERR)
+			break;
+		if (g == NULL)
+			continue;
+
+		/* do not return this loop if clipped, we want every character tested */
+		blf_glyph_render(font, g, (float)pen_x, (float)pen_y);
+
+		col = BLI_wcwidth((wchar_t)c);
+		if (col < 0)
+			col = 1;
+
+		columns += col;
+		pen_x += cwidth * col;
+	}
+
+	return columns;
+}
+
 /* Sanity checks are done by BLF_draw_buffer() */
 void blf_font_buffer(FontBLF *font, const char *str)
 {