From: Stefan Sperling <stsp@stsp.name>
Subject: tog: fix horizontal scrolling of unicode in the diff view
To: gameoftrees@openbsd.org
Date: Thu, 16 Jun 2022 16:32:33 +0200

Fix horizontal scrolling of unicode in the diff view. This makes
the diff in my ja.git test repo scroll properly.

Turns out we need another output parameter in format_line() for
this case. draw_file() needs to know the width of the unscrolled
version of each line in order to set view->maxx correctly.

ok?
 
diff 3a8eb03e7089a4869bb33afa6dc90d2b9d4c2c70 7c4eb5ef2ddd2fc6b8127a6b4746081efcb1411c
blob - 285021accb225e5cc858097d09e1a68d4b32e1ca
blob + 4b3a42b896e6f4177b004831b046fa812308b489
--- tog/tog.c
+++ tog/tog.c
@@ -1262,7 +1262,7 @@ expand_tab(char **ptr, const char *src)
  * Returns the index to the first character of the scrolled string.
  */
 static const struct got_error *
-scroll_wline(int *scrollx , wchar_t *wline, int nscroll,
+scroll_wline(int *scrollx, int *widthp, wchar_t *wline, int nscroll,
     int col_tab_align)
 {
 	int cols = 0;
@@ -1301,27 +1301,34 @@ scroll_wline(int *scrollx , wchar_t *wline, int nscrol
 	}
 
 	*scrollx = i;
+	*widthp = cols;
 	return NULL;
 }
 
 /*
  * Format a line for display, ensuring that it won't overflow a width limit.
- * With scrolling, the width returned refers to the scrolled version of the
- * line, which starts at (*wlinep)[*scrollxp]. The caller must free *wlinep.
+ * With scrolling, the width returned in *scrolled_widthp refers to the
+ * scrolled version of the line, which starts at (*wlinep)[*scrollxp].
+ * The caller must free *wlinep.
  */
 static const struct got_error *
-format_line(wchar_t **wlinep, int *widthp, int *scrollxp,
+format_line(wchar_t **wlinep, int *widthp, int *scrollxp, int *scrolled_widthp,
     const char *line, int nscroll, int wlimit, int col_tab_align, int expand)
 {
 	const struct got_error *err = NULL;
-	int cols = 0;
+	int cols = 0, skipped_cols = 0;
 	wchar_t *wline = NULL;
 	char *exstr = NULL;
 	size_t wlen;
 	int i, scrollx = 0;
 
 	*wlinep = NULL;
-	*widthp = 0;
+	if (widthp)
+		*widthp = 0;
+	if (scrollxp)
+		*scrollxp = 0;
+	if (scrolled_widthp)
+		*scrolled_widthp = 0;
 
 	if (expand) {
 		err = expand_tab(&exstr, line);
@@ -1334,7 +1341,8 @@ format_line(wchar_t **wlinep, int *widthp, int *scroll
 	if (err)
 		return err;
 
-	err = scroll_wline(&scrollx, wline, nscroll, col_tab_align);
+	err = scroll_wline(&scrollx, &skipped_cols, wline, nscroll,
+	    col_tab_align);
 	if (err)
 		goto done;
 
@@ -1380,9 +1388,11 @@ format_line(wchar_t **wlinep, int *widthp, int *scroll
 	}
 	wline[i] = L'\0';
 	if (widthp)
-		*widthp = cols;
+		*widthp = skipped_cols + cols;
 	if (scrollxp)
 		*scrollxp = scrollx;
+	if (scrolled_widthp)
+		*scrolled_widthp = cols;
 done:
 	if (err)
 		free(wline);
@@ -1469,7 +1479,7 @@ format_author(wchar_t **wauthor, int *author_width, ch
 	if (smallerthan && smallerthan[1] != '\0')
 		author = smallerthan + 1;
 	author[strcspn(author, "@>")] = '\0';
-	return format_line(wauthor, author_width, NULL, author, 0, limit,
+	return format_line(wauthor, author_width, NULL, NULL, author, 0, limit,
 	    col_tab_align, 0);
 }
 
@@ -1568,8 +1578,8 @@ draw_commit(struct tog_view *view, struct got_commit_o
 	if (newline)
 		*newline = '\0';
 	limit = avail - col;
-	err = format_line(&wlogmsg, &logmsg_width, &scrollx, logmsg, view->x,
-	    limit, col, 1);
+	err = format_line(&wlogmsg, NULL, &scrollx, &logmsg_width,
+	    logmsg, view->x, limit, col, 1);
 	if (err)
 		goto done;
 	waddwstr(view->window, &wlogmsg[scrollx]);
@@ -1810,7 +1820,8 @@ draw_commits(struct tog_view *view)
 		header = NULL;
 		goto done;
 	}
-	err = format_line(&wline, &width, NULL, header, 0, view->ncols, 0, 0);
+	err = format_line(&wline, &width, NULL, NULL, header, 0, view->ncols,
+	    0, 0);
 	if (err)
 		goto done;
 
@@ -1865,7 +1876,7 @@ draw_commits(struct tog_view *view)
 			++msg;
 		if ((eol = strchr(msg, '\n')))
 			*eol = '\0';
-		err = format_line(&wmsg, &width, NULL, msg, 0, INT_MAX,
+		err = format_line(&wmsg, &width, NULL, NULL, msg, 0, INT_MAX,
 		    date_display_cols + author_cols, 0);
 		if (err)
 			goto done;
@@ -3126,7 +3137,7 @@ add_matched_line(int *wtotal, const char *line, int wl
 	rms = regmatch->rm_so;
 	rme = regmatch->rm_eo;
 
-	err = format_line(&wline, &width, NULL, line, 0, wlimit + skip,
+	err = format_line(&wline, &width, NULL, NULL, line, 0, wlimit + skip,
 	    col_tab_align, 1);
 	if (err)
 		return err;
@@ -3196,8 +3207,8 @@ draw_file(struct tog_view *view, const char *header)
 		    s->first_displayed_line - 1 + s->selected_line, nlines,
 		    header) == -1)
 			return got_error_from_errno("asprintf");
-		err = format_line(&wline, &width, NULL, line, 0, view->ncols,
-		    0, 0);
+		err = format_line(&wline, &width, NULL, NULL, line, 0,
+		    view->ncols, 0, 0);
 		free(line);
 		if (err)
 			return err;
@@ -3231,8 +3242,6 @@ draw_file(struct tog_view *view, const char *header)
 			return got_ferror(s->f, GOT_ERR_IO);
 		}
 
-		view->maxx = MAX(view->maxx, linelen);
-
 		tc = match_color(&s->colors, line);
 		if (tc)
 			wattr_on(view->window,
@@ -3246,23 +3255,25 @@ draw_file(struct tog_view *view, const char *header)
 				return err;
 			}
 		} else {
-			err = format_line(&wline, &width, NULL, line, 0,
-			    view->x + view->ncols, 0, view->x ? 1 : 0);
+			int skip, fullwidth;
+			err = format_line(&wline, &fullwidth, &skip, &width,
+			    line, view->x, view->ncols, 0, view->x ? 1 : 0);
 			if (err) {
 				free(line);
 				return err;
 			}
-			if (view->x < width)
-				waddwstr(view->window, wline + view->x);
+			view->maxx = MAX(view->maxx, fullwidth);
+			waddwstr(view->window, &wline[skip]);
 			free(wline);
 			wline = NULL;
 		}
 		if (tc)
 			wattr_off(view->window,
 			    COLOR_PAIR(tc->colorpair), NULL);
-		if (width - view->x <= view->ncols - 1)
+		if (width <= view->ncols - 1)
 			waddch(view->window, '\n');
 		nprinted++;
+
 	}
 	free(line);
 	if (nprinted >= 1)
@@ -3279,7 +3290,7 @@ draw_file(struct tog_view *view, const char *header)
 			nprinted++;
 		}
 
-		err = format_line(&wline, &width, NULL, TOG_EOF_STRING, 0,
+		err = format_line(&wline, &width, NULL, NULL, TOG_EOF_STRING, 0,
 		    view->ncols, 0, 0);
 		if (err) {
 			return err;
@@ -4279,7 +4290,8 @@ draw_blame(struct tog_view *view)
 		return err;
 	}
 
-	err = format_line(&wline, &width, NULL, line, 0, view->ncols, 0, 0);
+	err = format_line(&wline, &width, NULL, NULL, line, 0, view->ncols,
+	    0, 0);
 	free(line);
 	line = NULL;
 	if (err)
@@ -4308,7 +4320,8 @@ draw_blame(struct tog_view *view)
 		return got_error_from_errno("asprintf");
 	}
 	free(id_str);
-	err = format_line(&wline, &width, NULL, line, 0, view->ncols, 0, 0);
+	err = format_line(&wline, &width, NULL, NULL, line, 0, view->ncols,
+	    0, 0);
 	free(line);
 	line = NULL;
 	if (err)
@@ -4395,7 +4408,7 @@ draw_blame(struct tog_view *view)
 			}
 			width += 9;
 		} else {
-			err = format_line(&wline, &width, NULL, line, 0,
+			err = format_line(&wline, &width, NULL, NULL, line, 0,
 			    view->x + view->ncols - 9, 9, 1);
 			if (err) {
 				free(line);
@@ -5273,8 +5286,8 @@ draw_tree_entries(struct tog_view *view, const char *p
 	if (limit == 0)
 		return NULL;
 
-	err = format_line(&wline, &width, NULL, s->tree_label, 0, view->ncols,
-	    0, 0);
+	err = format_line(&wline, &width, NULL, NULL, s->tree_label, 0,
+	    view->ncols, 0, 0);
 	if (err)
 		return err;
 	if (view_needs_focus_indication(view))
@@ -5295,8 +5308,8 @@ draw_tree_entries(struct tog_view *view, const char *p
 		waddch(view->window, '\n');
 	if (--limit <= 0)
 		return NULL;
-	err = format_line(&wline, &width, NULL, parent_path, 0, view->ncols,
-	    0, 0);
+	err = format_line(&wline, &width, NULL, NULL, parent_path, 0,
+	    view->ncols, 0, 0);
 	if (err)
 		return err;
 	waddwstr(view->window, wline);
@@ -5376,8 +5389,8 @@ draw_tree_entries(struct tog_view *view, const char *p
 		}
 		free(id_str);
 		free(link_target);
-		err = format_line(&wline, &width, NULL, line, 0, view->ncols,
-		    0, 0);
+		err = format_line(&wline, &width, NULL, NULL, line, 0,
+		    view->ncols, 0, 0);
 		if (err) {
 			free(line);
 			break;
@@ -6488,7 +6501,8 @@ show_ref_view(struct tog_view *view)
 	    s->nrefs) == -1)
 		return got_error_from_errno("asprintf");
 
-	err = format_line(&wline, &width, NULL, line, 0, view->ncols, 0, 0);
+	err = format_line(&wline, &width, NULL, NULL, line, 0, view->ncols,
+	    0, 0);
 	if (err) {
 		free(line);
 		return err;
@@ -6575,8 +6589,8 @@ show_ref_view(struct tog_view *view)
 		    got_ref_get_name(re->ref)) == -1)
 			return got_error_from_errno("asprintf");
 
-		err = format_line(&wline, &width, NULL, line, 0, view->ncols,
-		    0, 0);
+		err = format_line(&wline, &width, NULL, NULL, line, 0,
+		    view->ncols, 0, 0);
 		if (err) {
 			free(line);
 			return err;