===================================================================
RCS file: /cvsrepo/anoncvs/cvs/src/usr.bin/tmux/screen-write.c,v
retrieving revision 1.218
retrieving revision 1.219
diff -u -r1.218 -r1.219
--- src/usr.bin/tmux/screen-write.c	2023/08/15 07:01:47	1.218
+++ src/usr.bin/tmux/screen-write.c	2023/09/01 14:29:11	1.219
@@ -1,4 +1,4 @@
-/* $OpenBSD: screen-write.c,v 1.218 2023/08/15 07:01:47 nicm Exp $ */
+/* $OpenBSD: screen-write.c,v 1.219 2023/09/01 14:29:11 nicm Exp $ */
 
 /*
  * Copyright (c) 2007 Nicholas Marriott <nicholas.marriott@gmail.com>
@@ -1840,46 +1840,37 @@
 {
 	struct screen		*s = ctx->s;
 	struct grid		*gd = s->grid;
-	const struct utf8_data	*ud = &gc->data;
-	const struct utf8_data	 zwj = { "\342\200\215", 0, 3, 0 };
+	struct grid_cell	 copy;
+	const struct utf8_data	*ud = &gc->data, *previous = NULL, *combine;
 	struct grid_line	*gl;
 	struct grid_cell_entry	*gce;
 	struct grid_cell 	 tmp_gc, now_gc;
 	struct tty_ctx		 ttyctx;
 	u_int			 sx = screen_size_x(s), sy = screen_size_y(s);
-	u_int		 	 width = gc->data.width, xx, last, cx, cy;
+	u_int		 	 width = ud->width, xx, last, cx, cy;
 	int			 selected, skip = 1;
 
 	/* Ignore padding cells. */
 	if (gc->flags & GRID_FLAG_PADDING)
 		return;
 
-	/*
-	 * If this is a zero width joiner, set the flag so the next character
-	 * will be treated as zero width and appended. Note that we assume a
-	 * ZWJ will not change the width - the width of the first character is
-	 * used.
-	 */
-	if (ud->size == 3 && memcmp(ud->data, "\342\200\215", 3) == 0) {
-		log_debug("zero width joiner at %u,%u", s->cx, s->cy);
-		ctx->flags |= SCREEN_WRITE_ZWJ;
+	/* Check if this cell needs to be combined with the previous cell. */
+	if (ctx->flags & SCREEN_WRITE_COMBINE)
+		previous = &ctx->previous;
+	switch (utf8_try_combined(ud, previous, &combine, &width)) {
+	case UTF8_DISCARD_NOW:
+		log_debug("%s: UTF8_DISCARD_NOW (width %u)", __func__, width);
+		ctx->flags &= ~SCREEN_WRITE_COMBINE;
 		return;
-	}
-
-	/*
-	 * If the width is zero, combine onto the previous character. We always
-	 * combine with the cell to the left of the cursor position. In theory,
-	 * the application could have moved the cursor somewhere else, but if
-	 * they are silly enough to do that, who cares?
-	 */
-	if (ctx->flags & SCREEN_WRITE_ZWJ) {
+	case UTF8_WRITE_NOW:
+		log_debug("%s: UTF8_WRITE_NOW (width %u)", __func__, width);
+		ctx->flags &= ~SCREEN_WRITE_COMBINE;
+		break;
+	case UTF8_COMBINE_NOW:
+		log_debug("%s: UTF8_COMBINE_NOW (width %u)", __func__, width);
 		screen_write_collect_flush(ctx, 0, __func__);
-		screen_write_combine(ctx, &zwj, &xx, &cx);
-	}
-	if (width == 0 || (ctx->flags & SCREEN_WRITE_ZWJ)) {
-		ctx->flags &= ~SCREEN_WRITE_ZWJ;
-		screen_write_collect_flush(ctx, 0, __func__);
-		if ((gc = screen_write_combine(ctx, ud, &xx, &cx)) != NULL) {
+		gc = screen_write_combine(ctx, combine, &xx, &cx);
+		if (gc != NULL) {
 			cy = s->cy;
 			screen_write_set_cursor(ctx, xx, s->cy);
 			screen_write_initctx(ctx, &ttyctx, 0);
@@ -1887,8 +1878,27 @@
 			tty_write(tty_cmd_cell, &ttyctx);
 			s->cx = cx; s->cy = cy;
 		}
+		ctx->flags &= ~SCREEN_WRITE_COMBINE;
 		return;
+	case UTF8_WRITE_MAYBE_COMBINE:
+		log_debug("%s: UTF8_WRITE_MAYBE_COMBINE (width %u)", __func__,
+		    width);
+		utf8_copy(&ctx->previous, ud);
+		ctx->flags |= SCREEN_WRITE_COMBINE;
+		break;
+	case UTF8_DISCARD_MAYBE_COMBINE:
+		log_debug("%s: UTF8_DISCARD_MAYBE_COMBINE (width %u)", __func__,
+		    width);
+		utf8_copy(&ctx->previous, ud);
+		ctx->flags |= SCREEN_WRITE_COMBINE;
+		return;
 	}
+	if (width != ud->width) {
+		memcpy(&copy, gc, sizeof copy);
+		copy.data.width = width;
+		gc = &copy;
+	}
+	ud = NULL;
 
 	/* Flush any existing scrolling. */
 	screen_write_collect_flush(ctx, 1, __func__);