Improve cursor positioning after reflow by storing the position as an

offset into the entire history before reflow and restoring it aftewards.

3 files changed, 80 insertions, 73 deletions

diff --git a/usr.bin/tmux/grid.c b/usr.bin/tmux/grid.c
index a12ba180702..fbbc0712109 100644
--- a/usr.bin/tmux/grid.c
+++ b/usr.bin/tmux/grid.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: grid.c,v 1.90 2019/03/18 15:25:36 nicm Exp $ */
+/* $OpenBSD: grid.c,v 1.91 2019/03/20 19:19:11 nicm Exp $ */
 
 /*
  * Copyright (c) 2008 Nicholas Marriott <nicholas.marriott@gmail.com>
@@ -1030,7 +1030,7 @@ grid_reflow_move(struct grid *gd, struct grid_line *from)
 /* Join line below onto this one. */
 static void
 grid_reflow_join(struct grid *target, struct grid *gd, u_int sx, u_int yy,
-    u_int width, u_int *cy, int already)
+    u_int width, int already)
 {
 	struct grid_line	*gl, *from = NULL;
 	struct grid_cell	 gc;
@@ -1128,11 +1128,7 @@ grid_reflow_join(struct grid *target, struct grid *gd, u_int sx, u_int yy,
 		grid_reflow_dead(&gd->linedata[i]);
 	}
 
-	/* Adjust cursor and scroll positions. */
-	if (*cy > to + lines)
-		*cy -= lines;
-	else if (*cy > to)
-		*cy = to;
+	/* Adjust scroll position. */
 	if (gd->hscrolled > to + lines)
 		gd->hscrolled -= lines;
 	else if (gd->hscrolled > to)
@@ -1142,7 +1138,7 @@ grid_reflow_join(struct grid *target, struct grid *gd, u_int sx, u_int yy,
 /* Split this line into several new ones */
 static void
 grid_reflow_split(struct grid *target, struct grid *gd, u_int sx, u_int yy,
-    u_int at, u_int *cy)
+    u_int at)
 {
 	struct grid_line	*gl = &gd->linedata[yy], *first;
 	struct grid_cell	 gc;
@@ -1195,9 +1191,7 @@ grid_reflow_split(struct grid *target, struct grid *gd, u_int sx, u_int yy,
 	memcpy(first, gl, sizeof *first);
 	grid_reflow_dead(gl);
 
-	/* Adjust the cursor and scroll positions. */
-	if (yy <= *cy)
-		(*cy) += lines - 1;
+	/* Adjust the scroll position. */
 	if (yy <= gd->hscrolled)
 		gd->hscrolled += lines - 1;
 
@@ -1206,24 +1200,17 @@ grid_reflow_split(struct grid *target, struct grid *gd, u_int sx, u_int yy,
 	 * in the last new line, try to join with the next lines.
 	 */
 	if (width < sx && (flags & GRID_LINE_WRAPPED))
-		grid_reflow_join(target, gd, sx, yy, width, cy, 1);
+		grid_reflow_join(target, gd, sx, yy, width, 1);
 }
 
 /* Reflow lines on grid to new width. */
 void
-grid_reflow(struct grid *gd, u_int sx, u_int *cursor)
+grid_reflow(struct grid *gd, u_int sx)
 {
 	struct grid		*target;
 	struct grid_line	*gl;
 	struct grid_cell	 gc;
-	u_int			 yy, cy, width, i, at, first;
-	struct timeval		 start, tv;
-
-	gettimeofday(&start, NULL);
-
-	log_debug("%s: %u lines, new width %u", __func__, gd->hsize + gd->sy,
-	    sx);
-	cy = gd->hsize + (*cursor);
+	u_int			 yy, width, i, at, first;
 
 	/*
 	 * Create a destination grid. This is just used as a container for the
@@ -1277,7 +1264,7 @@ grid_reflow(struct grid *gd, u_int sx, u_int *cursor)
 		 * it was previously wrapped.
 		 */
 		if (width > sx) {
-			grid_reflow_split(target, gd, sx, yy, at, &cy);
+			grid_reflow_split(target, gd, sx, yy, at);
 			continue;
 		}
 
@@ -1286,7 +1273,7 @@ grid_reflow(struct grid *gd, u_int sx, u_int *cursor)
 		 * of the next line.
 		 */
 		if (gl->flags & GRID_LINE_WRAPPED)
-			grid_reflow_join(target, gd, sx, yy, width, &cy, 0);
+			grid_reflow_join(target, gd, sx, yy, width, 0);
 		else
 			grid_reflow_move(target, gl);
 	}
@@ -1300,20 +1287,42 @@ grid_reflow(struct grid *gd, u_int sx, u_int *cursor)
 	free(gd->linedata);
 	gd->linedata = target->linedata;
 	free(target);
+}
 
-	/*
-	 * Update scrolled and cursor positions.
-	 */
-	if (gd->hscrolled > gd->hsize)
-		gd->hscrolled = gd->hsize;
-	if (cy < gd->hsize)
-		*cursor = 0;
-	else
-		*cursor = cy - gd->hsize;
+/* Convert point position to offset from the start of the grid. */
+u_int
+grid_to_offset(struct grid *gd, u_int px, u_int py)
+{
+	u_int	yy, offset = 0;
+
+	if (py > gd->hsize + gd->sy - 1) {
+		px = UINT_MAX;
+		py = gd->hsize + gd->sy - 1;
+	}
 
-	gettimeofday(&tv, NULL);
-	timersub(&tv, &start, &tv);
-	log_debug("%s: now %u lines (in %llu.%06u seconds)", __func__,
-	    gd->hsize + gd->sy, (unsigned long long)tv.tv_sec,
-	    (u_int)tv.tv_usec);
+	for (yy = 0; yy < py; yy++)
+		offset += gd->linedata[yy].cellused;
+	if (px > gd->linedata[yy].cellused)
+		px = gd->linedata[yy].cellused;
+	return (offset + px);
+}
+
+/* Convert offset from the start of the grid to point position. */
+void
+grid_from_offset(struct grid *gd, u_int offset, u_int *px, u_int *py)
+{
+	u_int	yy;
+
+	*px = *py = 0;
+
+	for (yy = 0; yy < gd->hsize + gd->sy - 1; yy++) {
+		if (offset <= gd->linedata[yy].cellused)
+			break;
+		offset -= gd->linedata[yy].cellused;
+	}
+	if (offset < gd->linedata[yy].cellused)
+		*px = offset;
+	else
+		*px = gd->linedata[yy].cellused;
+	*py = yy;
 }
diff --git a/usr.bin/tmux/screen.c b/usr.bin/tmux/screen.c
index 6fa6cd4eb7d..14872531dba 100644
--- a/usr.bin/tmux/screen.c
+++ b/usr.bin/tmux/screen.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: screen.c,v 1.53 2019/01/15 09:56:31 nicm Exp $ */
+/* $OpenBSD: screen.c,v 1.54 2019/03/20 19:19:11 nicm Exp $ */
 
 /*
  * Copyright (c) 2007 Nicholas Marriott <nicholas.marriott@gmail.com>
@@ -48,7 +48,6 @@ struct screen_title_entry {
 };
 TAILQ_HEAD(screen_titles, screen_title_entry);
 
-static void	screen_resize_x(struct screen *, u_int);
 static void	screen_resize_y(struct screen *, u_int);
 
 static void	screen_reflow(struct screen *, u_int);
@@ -207,13 +206,7 @@ screen_resize(struct screen *s, u_int sx, u_int sy, int reflow)
 		sy = 1;
 
 	if (sx != screen_size_x(s)) {
-		screen_resize_x(s, sx);
-
-		/*
-		 * It is unclear what should happen to tabs on resize. xterm
-		 * seems to try and maintain them, rxvt resets them. Resetting
-		 * is simpler and more reliable so let's do that.
-		 */
+		s->grid->sx = sx;
 		screen_reset_tabs(s);
 	} else
 		reflow = 0;
@@ -226,28 +219,6 @@ screen_resize(struct screen *s, u_int sx, u_int sy, int reflow)
 }
 
 static void
-screen_resize_x(struct screen *s, u_int sx)
-{
-	struct grid		*gd = s->grid;
-
-	if (sx == 0)
-		fatalx("zero size");
-
-	/*
-	 * Treat resizing horizontally simply: just ensure the cursor is
-	 * on-screen and change the size. Don't bother to truncate any lines -
-	 * then the data should be accessible if the size is then increased.
-	 *
-	 * The only potential wrinkle is if UTF-8 double-width characters are
-	 * left in the last column, but UTF-8 terminals should deal with this
-	 * sanely.
-	 */
-	if (s->cx >= sx)
-		s->cx = sx - 1;
-	gd->sx = sx;
-}
-
-static void
 screen_resize_y(struct screen *s, u_int sy)
 {
 	struct grid	*gd = s->grid;
@@ -493,5 +464,30 @@ screen_select_cell(struct screen *s, struct grid_cell *dst,
 static void
 screen_reflow(struct screen *s, u_int new_x)
 {
-	grid_reflow(s->grid, new_x, &s->cy);
+	u_int		offset, cx = s->cx, cy = s->grid->hsize + s->cy;
+	struct timeval	start, tv;
+
+	gettimeofday(&start, NULL);
+
+	offset = grid_to_offset(s->grid, cx, cy);
+	log_debug("%s: cursor %u,%u offset is %u", __func__, cx, cy, offset);
+
+	grid_reflow(s->grid, new_x);
+
+	grid_from_offset(s->grid, offset, &cx, &cy);
+	log_debug("%s: new cursor is %u,%u", __func__, cx, cy);
+
+	if (cy >= s->grid->hsize) {
+		s->cx = cx;
+		s->cy = cy - s->grid->hsize;
+	} else {
+		s->cx = 0;
+		s->cy = 0;
+	}
+
+	gettimeofday(&tv, NULL);
+	timersub(&tv, &start, &tv);
+
+	log_debug("%s: reflow took %llu.%06u seconds", __func__,
+	    (unsigned long long)tv.tv_sec, (u_int)tv.tv_usec);
 }
diff --git a/usr.bin/tmux/tmux.h b/usr.bin/tmux/tmux.h
index 6ce73b24bfb..944ab89aeaf 100644
--- a/usr.bin/tmux/tmux.h
+++ b/usr.bin/tmux/tmux.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: tmux.h,v 1.875 2019/03/18 21:46:02 nicm Exp $ */
+/* $OpenBSD: tmux.h,v 1.876 2019/03/20 19:19:11 nicm Exp $ */
 
 /*
  * Copyright (c) 2007 Nicholas Marriott <nicholas.marriott@gmail.com>
@@ -2088,6 +2088,8 @@ void	 grid_get_cell(struct grid *, u_int, u_int, struct grid_cell *);
 void	 grid_set_cell(struct grid *, u_int, u_int, const struct grid_cell *);
 void	 grid_set_cells(struct grid *, u_int, u_int, const struct grid_cell *,
 	     const char *, size_t);
+struct grid_line *grid_get_line(struct grid *, u_int);
+void	 grid_adjust_lines(struct grid *, u_int);
 void	 grid_clear(struct grid *, u_int, u_int, u_int, u_int, u_int);
 void	 grid_clear_lines(struct grid *, u_int, u_int, u_int);
 void	 grid_move_lines(struct grid *, u_int, u_int, u_int, u_int);
@@ -2096,9 +2098,9 @@ char	*grid_string_cells(struct grid *, u_int, u_int, u_int,
 	     struct grid_cell **, int, int, int);
 void	 grid_duplicate_lines(struct grid *, u_int, struct grid *, u_int,
 	     u_int);
-void	 grid_reflow(struct grid *, u_int, u_int *);
-struct grid_line *grid_get_line(struct grid *, u_int);
-void	 grid_adjust_lines(struct grid *, u_int);
+void	 grid_reflow(struct grid *, u_int);
+u_int	 grid_to_offset(struct grid *, u_int, u_int);
+void	 grid_from_offset(struct grid *, u_int, u_int *, u_int *);
 
 /* grid-view.c */
 void	 grid_view_get_cell(struct grid *, u_int, u_int, struct grid_cell *);