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, 83 insertions, 36 deletions

diff --git a/source/blender/editors/space_info/textview.c b/source/blender/editors/space_info/textview.c
index 66f4904c340..58418f2befd 100644
--- a/source/blender/editors/space_info/textview.c
+++ b/source/blender/editors/space_info/textview.c
@@ -31,14 +31,19 @@
 #include <limits.h>
 #include <assert.h>
 
+#include "MEM_guardedalloc.h"
+
 #include "BLF_api.h"
 
 #include "BLI_math.h"
 #include "BLI_utildefines.h"
+#include "BLI_string_utf8.h"
 
 #include "BIF_gl.h"
 #include "BIF_glutil.h"
 
+#include "BKE_text.h"
+
 #include "ED_datafiles.h"
 
 #include "textview.h"
@@ -68,12 +73,12 @@ BLI_INLINE void console_step_sel(ConsoleDrawContext *cdc, const int step)
 	cdc->sel[1] += step;
 }
 
-static void console_draw_sel(const int sel[2], const int xy[2], const int str_len_draw, int cwidth, int lheight,
-                             const unsigned char bg_sel[4])
+static void console_draw_sel(const char *str, const int sel[2], const int xy[2], const int str_len_draw,
+			     int cwidth, int lheight, const unsigned char bg_sel[4])
 {
 	if (sel[0] <= str_len_draw && sel[1] >= 0) {
-		const int sta = max_ii(sel[0], 0);
-		const int end = min_ii(sel[1], str_len_draw);
+		const int sta = txt_utf8_offset_to_column(str, max_ii(sel[0], 0));
+		const int end = txt_utf8_offset_to_column(str, min_ii(sel[1], str_len_draw));
 
 		glEnable(GL_BLEND);
 		glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
@@ -85,38 +90,72 @@ static void console_draw_sel(const int sel[2], const int xy[2], const int str_le
 	}
 }
 
+/* warning: allocated memory for 'offsets' must be freed by caller */
+static int console_wrap_offsets(const char *str, int len, int width, int *lines, int **offsets)
+{
+	int i, end;  /* column */
+	int j;       /* mem */
+
+	*lines = 1;
+
+	*offsets = MEM_callocN(sizeof(**offsets) * (len * BLI_UTF8_WIDTH_MAX / MAX2(1, width - (BLI_UTF8_WIDTH_MAX - 1)) + 1),
+			       "console_wrap_offsets");
+	(*offsets)[0] = 0;
+
+	for (i = 0, end = width, j = 0; j < len && str[j]; j += BLI_str_utf8_size_safe(str + j)) {
+		int columns = BLI_str_utf8_char_width_safe(str + j);
+
+		if (i + columns > end) {
+			(*offsets)[*lines] = j;
+			(*lines)++;
+
+			end = i + width;
+		}
+		i += columns;
+	}
+	return j; /* return actual length */
+}
+
 /* return 0 if the last line is off the screen
  * should be able to use this for any string type */
 
-static int console_draw_string(ConsoleDrawContext *cdc, const char *str, const int str_len,
+static int console_draw_string(ConsoleDrawContext *cdc, const char *str, int str_len,
                                const unsigned char fg[3], const unsigned char bg[3], const unsigned char bg_sel[4])
 {
 	int rct_ofs = cdc->lheight / 4;
-	int tot_lines = (str_len / cdc->console_width) + 1; /* total number of lines for wrapping */
-	int y_next = (str_len > cdc->console_width) ? cdc->xy[1] + cdc->lheight * tot_lines : cdc->xy[1] + cdc->lheight;
+	int tot_lines;            /* total number of lines for wrapping */
+	int *offsets;             /* offsets of line beginnings for wrapping */
+	int y_next;
 	const int mono = blf_mono_font;
 
+	str_len = console_wrap_offsets(str, str_len, cdc->console_width, &tot_lines, &offsets);
+	y_next = cdc->xy[1] + cdc->lheight * tot_lines;
+
 	/* just advance the height */
 	if (cdc->draw == 0) {
-		if (cdc->pos_pick && (cdc->mval[1] != INT_MAX)) {
-			if (cdc->xy[1] <= cdc->mval[1]) {
-				if ((y_next >= cdc->mval[1])) {
-					int ofs = (int)floor(((float)cdc->mval[0] / (float)cdc->cwidth));
-
-					/* wrap */
-					if (str_len > cdc->console_width)
-						ofs += cdc->console_width * ((int)((((float)(y_next - cdc->mval[1]) /
-						                                     (float)(y_next - cdc->xy[1])) * tot_lines)));
-	
-					CLAMP(ofs, 0, str_len);
-					*cdc->pos_pick += str_len - ofs;
+		if (cdc->pos_pick && cdc->mval[1] != INT_MAX && cdc->xy[1] <= cdc->mval[1]) {
+			if (y_next >= cdc->mval[1]) {
+				int ofs = 0;
+
+				/* wrap */
+				if (tot_lines > 1) {
+					int iofs = (int)((float)(y_next - cdc->mval[1]) / cdc->lheight);
+					ofs += offsets[MIN2(iofs, tot_lines - 1)];
 				}
-				else
-					*cdc->pos_pick += str_len + 1;
+
+				/* last part */
+				ofs += txt_utf8_column_to_offset(str + ofs,
+								 (int)floor((float)cdc->mval[0] / cdc->cwidth));
+
+				CLAMP(ofs, 0, str_len);
+				*cdc->pos_pick += str_len - ofs;
 			}
+			else
+				*cdc->pos_pick += str_len + 1;
 		}
 
 		cdc->xy[1] = y_next;
+		MEM_freeN(offsets);
 		return 1;
 	}
 	else if (y_next - cdc->lheight < cdc->ymin) {
@@ -128,12 +167,15 @@ static int console_draw_string(ConsoleDrawContext *cdc, const char *str, const i
 			console_step_sel(cdc, -(str_len + 1));
 		}
 
+		MEM_freeN(offsets);
 		return 1;
 	}
 
 	if (tot_lines > 1) { /* wrap? */
-		const int initial_offset = ((tot_lines - 1) * cdc->console_width);
-		const char *line_stride = str + initial_offset;  /* advance to the last line and draw it first */
+		const int initial_offset = offsets[tot_lines - 1];
+		size_t len = str_len - initial_offset;
+		const char *s = str + initial_offset;
+		int i;
 		
 		int sel_orig[2];
 		copy_v2_v2_int(sel_orig, cdc->sel);
@@ -151,36 +193,38 @@ static int console_draw_string(ConsoleDrawContext *cdc, const char *str, const i
 
 		/* last part needs no clipping */
 		BLF_position(mono, cdc->xy[0], cdc->xy[1], 0);
-		BLF_draw(mono, line_stride, str_len - initial_offset);
+		BLF_draw_mono(mono, s, len, cdc->cwidth);
 
 		if (cdc->sel[0] != cdc->sel[1]) {
 			console_step_sel(cdc, -initial_offset);
 			// glColor4ub(255, 0, 0, 96); // debug
-			console_draw_sel(cdc->sel, cdc->xy, str_len % cdc->console_width, cdc->cwidth, cdc->lheight, bg_sel);
-			console_step_sel(cdc, cdc->console_width);
+			console_draw_sel(s, cdc->sel, cdc->xy, len, cdc->cwidth, cdc->lheight, bg_sel);
 			glColor3ubv(fg);
 		}
 
 		cdc->xy[1] += cdc->lheight;
 
-		line_stride -= cdc->console_width;
-		
-		for (; line_stride >= str; line_stride -= cdc->console_width) {
+		for (i = tot_lines - 1; i > 0; i--) {
+			len = offsets[i] - offsets[i - 1];
+			s = str + offsets[i - 1];
+
 			BLF_position(mono, cdc->xy[0], cdc->xy[1], 0);
-			BLF_draw(mono, line_stride, cdc->console_width);
+			BLF_draw_mono(mono, s, len, cdc->cwidth);
 			
 			if (cdc->sel[0] != cdc->sel[1]) {
+				console_step_sel(cdc, len);
 				// glColor4ub(0, 255, 0, 96); // debug
-				console_draw_sel(cdc->sel, cdc->xy, cdc->console_width, cdc->cwidth, cdc->lheight, bg_sel);
-				console_step_sel(cdc, cdc->console_width);
+				console_draw_sel(s, cdc->sel, cdc->xy, len, cdc->cwidth, cdc->lheight, bg_sel);
 				glColor3ubv(fg);
 			}
 
 			cdc->xy[1] += cdc->lheight;
 			
 			/* check if were out of view bounds */
-			if (cdc->xy[1] > cdc->ymax)
+			if (cdc->xy[1] > cdc->ymax) {
+				MEM_freeN(offsets);
 				return 0;
+			}
 		}
 
 		copy_v2_v2_int(cdc->sel, sel_orig);
@@ -196,7 +240,7 @@ static int console_draw_string(ConsoleDrawContext *cdc, const char *str, const i
 		glColor3ubv(fg);
 
 		BLF_position(mono, cdc->xy[0], cdc->xy[1], 0);
-		BLF_draw(mono, str, str_len);
+		BLF_draw_mono(mono, str, str_len, cdc->cwidth);
 		
 		if (cdc->sel[0] != cdc->sel[1]) {
 			int isel[2];
@@ -205,16 +249,19 @@ static int console_draw_string(ConsoleDrawContext *cdc, const char *str, const i
 			isel[1] = str_len - cdc->sel[0];
 
 			// glColor4ub(255, 255, 0, 96); // debug
-			console_draw_sel(isel, cdc->xy, str_len, cdc->cwidth, cdc->lheight, bg_sel);
+			console_draw_sel(str, isel, cdc->xy, str_len, cdc->cwidth, cdc->lheight, bg_sel);
 			console_step_sel(cdc, -(str_len + 1));
 		}
 
 		cdc->xy[1] += cdc->lheight;
 
-		if (cdc->xy[1] > cdc->ymax)
+		if (cdc->xy[1] > cdc->ymax) {
+			MEM_freeN(offsets);
 			return 0;
+		}
 	}
 
+	MEM_freeN(offsets);
 	return 1;
 }