Add scroll-top and scroll-bottom commands to scroll so cursor is at top

or bottom. From Anindya Mukherjee, GitHub issue 3334.

tmux.1

@@ -1808,7 +1808,9 @@ The following commands are supported in copy mode:
 .It Li "search-forward <for>" Ta "/" Ta ""
 .It Li "search-forward-incremental <for>" Ta "" Ta "C-s"
 .It Li "search-forward-text <for>" Ta "" Ta ""
+.It Li "scroll-bottom" Ta "" Ta ""
 .It Li "scroll-middle" Ta "z" Ta ""
+.It Li "scroll-top" Ta "" Ta ""
 .It Li "search-reverse" Ta "N" Ta "N"
 .It Li "select-line" Ta "V" Ta ""
 .It Li "select-word" Ta "" Ta ""
@@ -2011,7 +2013,7 @@ but a different format may be specified with
 .Fl F .
 .Tg capturep
 .It Xo Ic capture-pane
-.Op Fl aepPqCJN
+.Op Fl aAepPqCJN
 .Op Fl b Ar buffer-name
 .Op Fl E Ar end-line
 .Op Fl S Ar start-line
@@ -2036,10 +2038,15 @@ is given, the output includes escape sequences for text and background
 attributes.
 .Fl C
 also escapes non-printable characters as octal \exxx.
+.Fl T
+ignores trailing positions that do not contain a character.
 .Fl N
 preserves trailing spaces at each line's end and
 .Fl J
-preserves trailing spaces and joins any wrapped lines.
+preserves trailing spaces and joins any wrapped lines;
+.Fl J
+implies
+.Fl T .
 .Fl P
 captures only any output that the pane has received that is the beginning of an
 as-yet incomplete escape sequence.

window-copy.c

@@ -1250,20 +1250,23 @@ window_copy_cmd_cursor_right(struct window_copy_cmd_state *cs)
 	return (WINDOW_COPY_CMD_NOTHING);
 }
 
+/* Scroll line containing the cursor to the given position. */
 static enum window_copy_cmd_action
-window_copy_cmd_scroll_middle(struct window_copy_cmd_state *cs)
+window_copy_cmd_scroll_to(struct window_copy_cmd_state *cs, u_int to)
 {
 	struct window_mode_entry	*wme = cs->wme;
 	struct window_copy_mode_data	*data = wme->data;
-	u_int				 mid_value, oy, delta;
+	u_int				 oy, delta;
 	int				 scroll_up; /* >0 up, <0 down */
 
-	mid_value = (screen_size_y(&data->screen) - 1) / 2;
+	scroll_up = data->cy - to;
-	scroll_up = data->cy - mid_value;
 	delta = abs(scroll_up);
-	oy = screen_hsize(data->backing) + data->cy - data->oy;
+	oy = screen_hsize(data->backing) - data->oy;
 
-	log_debug ("XXX %u %u %u %d %u", mid_value, oy, delta, scroll_up, data->oy);
+	/*
+	 * oy is the maximum scroll down amount, while data->oy is the maximum
+	 * scroll up amount.
+	 */
 	if (scroll_up > 0 && data->oy >= delta) {
 		window_copy_scroll_up(wme, delta);
 		data->cy -= delta;
@@ -1276,6 +1279,35 @@ window_copy_cmd_scroll_middle(struct window_copy_cmd_state *cs)
 	return (WINDOW_COPY_CMD_REDRAW);
 }
 
+/* Scroll line containing the cursor to the bottom. */
+static enum window_copy_cmd_action
+window_copy_cmd_scroll_bottom(struct window_copy_cmd_state *cs)
+{
+	struct window_copy_mode_data	*data = cs->wme->data;
+	u_int				 bottom;
+
+	bottom = screen_size_y(&data->screen) - 1;
+	return (window_copy_cmd_scroll_to(cs, bottom));
+}
+
+/* Scroll line containing the cursor to the middle. */
+static enum window_copy_cmd_action
+window_copy_cmd_scroll_middle(struct window_copy_cmd_state *cs)
+{
+	struct window_copy_mode_data	*data = cs->wme->data;
+	u_int				 mid_value;
+
+	mid_value = (screen_size_y(&data->screen) - 1) / 2;
+	return (window_copy_cmd_scroll_to(cs, mid_value));
+}
+
+/* Scroll line containing the cursor to the top. */
+static enum window_copy_cmd_action
+window_copy_cmd_scroll_top(struct window_copy_cmd_state *cs)
+{
+	return (window_copy_cmd_scroll_to(cs, 0));
+}
+
 static enum window_copy_cmd_action
 window_copy_cmd_cursor_up(struct window_copy_cmd_state *cs)
 {
@@ -2794,6 +2826,12 @@ static const struct {
 	  .clear = WINDOW_COPY_CMD_CLEAR_ALWAYS,
 	  .f = window_copy_cmd_refresh_from_pane
 	},
+	{ .command = "scroll-bottom",
+	  .minargs = 0,
+	  .maxargs = 0,
+	  .clear = WINDOW_COPY_CMD_CLEAR_ALWAYS,
+	  .f = window_copy_cmd_scroll_bottom
+	},
 	{ .command = "scroll-down",
 	  .minargs = 0,
 	  .maxargs = 0,
@@ -2812,6 +2850,12 @@ static const struct {
 	  .clear = WINDOW_COPY_CMD_CLEAR_ALWAYS,
 	  .f = window_copy_cmd_scroll_middle
 	},
+	{ .command = "scroll-top",
+	  .minargs = 0,
+	  .maxargs = 0,
+	  .clear = WINDOW_COPY_CMD_CLEAR_ALWAYS,
+	  .f = window_copy_cmd_scroll_top
+	},
 	{ .command = "scroll-up",
 	  .minargs = 0,
 	  .maxargs = 0,