From b0a37e7514f2e08a9a8315cc68add4f0a53ed2af Mon Sep 17 00:00:00 2001
From: nicm <nicm>
Date: Sat, 18 Apr 2020 07:32:53 +0000
Subject: [PATCH] Bring back previons fix to only redraw panes that need it
 after a redraw is deferred, but clear the pane flags when they are actually
 redrawn rather than every time.

---
 screen-redraw.c |  2 ++
 server-client.c | 18 ++++++++----------
 tmux.h          |  4 +++-
 tty.c           | 10 ++++++++++
 4 files changed, 23 insertions(+), 11 deletions(-)

diff --git a/screen-redraw.c b/screen-redraw.c
index c9e70590..4c017706 100644
--- a/screen-redraw.c
+++ b/screen-redraw.c
@@ -474,6 +474,7 @@ screen_redraw_pane(struct client *c, struct window_pane *wp)
 	tty_sync_start(&c->tty);
 
 	screen_redraw_draw_pane(&ctx, wp);
+	wp->flags &= ~PANE_REDRAW;
 
 	tty_reset(&c->tty);
 	tty_sync_end(&c->tty);
@@ -563,6 +564,7 @@ screen_redraw_draw_panes(struct screen_redraw_ctx *ctx)
 	TAILQ_FOREACH(wp, &w->panes, entry) {
 		if (window_pane_visible(wp))
 			screen_redraw_draw_pane(ctx, wp);
+		wp->flags &= ~PANE_REDRAW;
 	}
 }
 
diff --git a/server-client.c b/server-client.c
index cd301bbd..14691fdc 100644
--- a/server-client.c
+++ b/server-client.c
@@ -1370,7 +1370,6 @@ server_client_loop(void)
 				if (resize)
 					server_client_check_resize(wp);
 			}
-			wp->flags &= ~PANE_REDRAW;
 		}
 		check_window_name(w);
 	}
@@ -1681,7 +1680,7 @@ server_client_check_redraw(struct client *c)
 	struct session		*s = c->session;
 	struct tty		*tty = &c->tty;
 	struct window_pane	*wp;
-	int			 needed, flags, mode = tty->mode;
+	int			 needed, flags, mode = tty->mode, new_flags = 0;
 	struct timeval		 tv = { .tv_usec = 1000 };
 	static struct event	 ev;
 	size_t			 left;
@@ -1689,11 +1688,12 @@ server_client_check_redraw(struct client *c)
 	if (c->flags & (CLIENT_CONTROL|CLIENT_SUSPENDED))
 		return;
 	if (c->flags & CLIENT_ALLREDRAWFLAGS) {
-		log_debug("%s: redraw%s%s%s%s", c->name,
+		log_debug("%s: redraw%s%s%s%s%s", c->name,
 		    (c->flags & CLIENT_REDRAWWINDOW) ? " window" : "",
 		    (c->flags & CLIENT_REDRAWSTATUS) ? " status" : "",
 		    (c->flags & CLIENT_REDRAWBORDERS) ? " borders" : "",
-		    (c->flags & CLIENT_REDRAWOVERLAY) ? " overlay" : "");
+		    (c->flags & CLIENT_REDRAWOVERLAY) ? " overlay" : "",
+		    (c->flags & CLIENT_REDRAWPANES) ? " panes" : "");
 	}
 
 	/*
@@ -1711,6 +1711,8 @@ server_client_check_redraw(struct client *c)
 				break;
 			}
 		}
+		if (needed)
+			new_flags |= CLIENT_REDRAWPANES;
 	}
 	if (needed && (left = EVBUFFER_LENGTH(tty->out)) != 0) {
 		log_debug("%s: redraw deferred (%zu left)", c->name, left);
@@ -1720,12 +1722,7 @@ server_client_check_redraw(struct client *c)
 			log_debug("redraw timer started");
 			evtimer_add(&ev, &tv);
 		}
-
-		/*
-		 * We may have got here for a single pane redraw, but force a
-		 * full redraw next time in case other panes have been updated.
-		 */
-		c->flags |= CLIENT_ALLREDRAWFLAGS;
+		c->flags |= new_flags;
 		return;
 	} else if (needed)
 		log_debug("%s: redraw needed", c->name);
@@ -1745,6 +1742,7 @@ server_client_check_redraw(struct client *c)
 				screen_redraw_pane(c, wp);
 			}
 		}
+		c->flags &= ~CLIENT_REDRAWPANES;
 	}
 
 	if (c->flags & CLIENT_ALLREDRAWFLAGS) {
diff --git a/tmux.h b/tmux.h
index e5d7be90..64b09abf 100644
--- a/tmux.h
+++ b/tmux.h
@@ -1542,12 +1542,14 @@ struct client {
 #define CLIENT_CONTROL_NOOUTPUT 0x4000000
 #define CLIENT_DEFAULTSOCKET 0x8000000
 #define CLIENT_STARTSERVER 0x10000000
+#define CLIENT_REDRAWPANES 0x20000000
 #define CLIENT_ALLREDRAWFLAGS		\
 	(CLIENT_REDRAWWINDOW|		\
 	 CLIENT_REDRAWSTATUS|		\
 	 CLIENT_REDRAWSTATUSALWAYS|	\
 	 CLIENT_REDRAWBORDERS|		\
-	 CLIENT_REDRAWOVERLAY)
+	 CLIENT_REDRAWOVERLAY|		\
+	 CLIENT_REDRAWPANES)
 #define CLIENT_UNATTACHEDFLAGS	\
 	(CLIENT_DEAD|		\
 	 CLIENT_SUSPENDED|	\
diff --git a/tty.c b/tty.c
index 92827f5d..cdfedf6c 100644
--- a/tty.c
+++ b/tty.c
@@ -944,6 +944,7 @@ tty_fake_bce(const struct tty *tty, struct window_pane *wp, u_int bg)
 static void
 tty_redraw_region(struct tty *tty, const struct tty_ctx *ctx)
 {
+	struct client		*c = tty->client;
 	struct window_pane	*wp = ctx->wp;
 	struct screen		*s = wp->screen;
 	u_int			 i;
@@ -953,6 +954,7 @@ tty_redraw_region(struct tty *tty, const struct tty_ctx *ctx)
 	 * likely to be followed by some more scrolling.
 	 */
 	if (tty_large_region(tty, ctx)) {
+		log_debug("%s: %s, large redraw of %%%u", __func__, c->name, wp->id);
 		wp->flags |= PANE_REDRAW;
 		return;
 	}
@@ -1484,6 +1486,14 @@ tty_write(void (*cmdfn)(struct tty *, const struct tty_ctx *),
 	TAILQ_FOREACH(c, &clients, entry) {
 		if (!tty_client_ready(c, wp))
 			continue;
+		if (c->flags & CLIENT_REDRAWPANES) {
+			/*
+			 * Redraw is already deferred to redraw another pane -
+			 * redraw this one also when that happens.
+			 */
+			wp->flags |= PANE_REDRAW;
+			break;
+		}
 
 		ctx->bigger = tty_window_offset(&c->tty, &ctx->ox, &ctx->oy,
 		    &ctx->sx, &ctx->sy);