From ad566a86de2368aa4a42cd26dafecc066cff41eb Mon Sep 17 00:00:00 2001
From: Nicholas Marriott <nicm@openbsd.org>
Date: Tue, 13 Oct 2009 15:38:37 +0000
Subject: [PATCH] Move lines into the history when scrolling even if the scroll
 region is not the entire screen.

Allows ircII users to see history, prompted by naddy.
---
 grid-view.c | 21 ++++++++++------
 grid.c      | 70 ++++++++++++++++++++++++++++++++++++++++++++---------
 tmux.h      |  4 ++-
 3 files changed, 75 insertions(+), 20 deletions(-)

diff --git a/grid-view.c b/grid-view.c
index bf58c61f..f6bde853 100644
--- a/grid-view.c
+++ b/grid-view.c
@@ -92,15 +92,20 @@ grid_view_scroll_region_up(struct grid *gd, u_int rupper, u_int rlower)
 {
 	GRID_DEBUG(gd, "rupper=%u, rlower=%u", rupper, rlower);
 
-	if (gd->flags & GRID_HISTORY && rupper == 0 && rlower == gd->sy - 1) {
-		grid_scroll_line(gd);
-		return;
+	if (gd->flags & GRID_HISTORY) {
+		grid_collect_history(gd);
+		if (rupper == 0 && rlower == gd->sy - 1)
+			grid_scroll_history(gd);
+		else {
+			rupper = grid_view_y(gd, rupper);
+			rlower = grid_view_y(gd, rlower);
+			grid_scroll_history_region(gd, rupper, rlower);
+		}
+	} else {
+		rupper = grid_view_y(gd, rupper);
+		rlower = grid_view_y(gd, rlower);
+		grid_move_lines(gd, rupper, rupper + 1, rlower - rupper);
 	}
-
-	rupper = grid_view_y(gd, rupper);
-	rlower = grid_view_y(gd, rlower);
-
-	grid_move_lines(gd, rupper, rupper + 1, rlower - rupper);
 }
 
 /* Scroll region down. */
diff --git a/grid.c b/grid.c
index 6e01aa7c..1041528d 100644
--- a/grid.c
+++ b/grid.c
@@ -161,29 +161,77 @@ grid_compare(struct grid *ga, struct grid *gb)
 	return (0);
 }
 
-/* Scroll a line into the history. */
+/*
+ * Collect lines from the history if at the limit. Free the top (oldest) 10%
+ * and shift up.
+ */
 void
-grid_scroll_line(struct grid *gd)
+grid_collect_history(struct grid *gd)
 {
 	u_int	yy;
 
  	GRID_DEBUG(gd, "");
 
-	if (gd->hsize >= gd->hlimit) {
-		/* If the limit is hit, free the bottom 10% and shift up. */
-		yy = gd->hlimit / 10;
-		if (yy < 1)
-			yy = 1;
+	if (gd->hsize < gd->hlimit)
+		return;
 
-		grid_move_lines(gd, 0, yy, gd->hsize + gd->sy - yy);
-		gd->hsize -= yy;
-	}
+	yy = gd->hlimit / 10;
+	if (yy < 1)
+		yy = 1;
+
+	grid_move_lines(gd, 0, yy, gd->hsize + gd->sy - yy);
+	gd->hsize -= yy;
+}
+
+/* 
+ * Scroll the entire visible screen, moving one line into the history. Just
+ * allocate a new line at the bottom and move the history size indicator.
+ */
+void
+grid_scroll_history(struct grid *gd)
+{
+	u_int	yy;
+
+ 	GRID_DEBUG(gd, "");
 
 	yy = gd->hsize + gd->sy;
-
 	gd->linedata = xrealloc(gd->linedata, yy + 1, sizeof *gd->linedata);
 	memset(&gd->linedata[yy], 0, sizeof gd->linedata[yy]);
+	
+	gd->hsize++;
+}
 
+/* Scroll a region up, moving the top line into the history. */
+void
+grid_scroll_history_region(struct grid *gd, u_int upper, u_int lower)
+{
+	struct grid_line	*gl_history, *gl_upper, *gl_lower;
+	u_int			 yy;
+
+ 	GRID_DEBUG(gd, "upper=%u, lower=%u", upper, lower);
+
+	/* Create a space for a new line. */
+	yy = gd->hsize + gd->sy;
+	gd->linedata = xrealloc(gd->linedata, yy + 1, sizeof *gd->linedata);
+
+	/* Move the entire screen down to free a space for this line. */
+	gl_history = &gd->linedata[gd->hsize];
+	memmove(gl_history + 1, gl_history, gd->sy * sizeof *gl_history);
+
+	/* Adjust the region and find its start and end. */
+	upper++;
+	gl_upper = &gd->linedata[upper];
+	lower++;
+	gl_lower = &gd->linedata[lower];
+
+	/* Move the line into the history. */
+	memcpy(gl_history, gl_upper, sizeof *gl_history);
+
+	/* Then move the region up and clear the bottom line. */
+	memmove(gl_upper, gl_upper + 1, (lower - upper) * sizeof *gl_upper);
+	memset(gl_lower, 0, sizeof *gl_lower);
+
+	/* Move the history offset down over the line. */
 	gd->hsize++;
 }
 
diff --git a/tmux.h b/tmux.h
index 35a542fa..0dcf7c37 100644
--- a/tmux.h
+++ b/tmux.h
@@ -1592,9 +1592,11 @@ extern const struct grid_cell grid_default_cell;
 struct grid *grid_create(u_int, u_int, u_int);
 void	 grid_destroy(struct grid *);
 int	 grid_compare(struct grid *, struct grid *);
+void	 grid_collect_history(struct grid *);
+void	 grid_scroll_history(struct grid *);
+void	 grid_scroll_history_region(struct grid *, u_int, u_int);
 void	 grid_expand_line(struct grid *, u_int, u_int);
 void	 grid_expand_line_utf8(struct grid *, u_int, u_int);
-void	 grid_scroll_line(struct grid *);
 const struct grid_cell *grid_peek_cell(struct grid *, u_int, u_int);
 struct grid_cell *grid_get_cell(struct grid *, u_int, u_int);
 void	 grid_set_cell(struct grid *, u_int, u_int, const struct grid_cell *);