From 416c27c9958e928b9ff845c1701acf5b10d0db8d Mon Sep 17 00:00:00 2001
From: nicm <nicm>
Date: Tue, 23 Aug 2022 08:14:19 +0000
Subject: Add scroll-middle copy mode command to make cursor line in the
 middle, from Varun Kumar E in GitHub issue 3307.

---
 window-copy.c | 32 ++++++++++++++++++++++++++++++++
 1 file changed, 32 insertions(+)

(limited to 'window-copy.c')

diff --git a/window-copy.c b/window-copy.c
index 834a2d99..743364d6 100644
--- a/window-copy.c
+++ b/window-copy.c
@@ -1250,6 +1250,32 @@ window_copy_cmd_cursor_right(struct window_copy_cmd_state *cs)
 	return (WINDOW_COPY_CMD_NOTHING);
 }
 
+static enum window_copy_cmd_action
+window_copy_cmd_scroll_middle(struct window_copy_cmd_state *cs)
+{
+	struct window_mode_entry	*wme = cs->wme;
+	struct window_copy_mode_data	*data = wme->data;
+	u_int				 mid_value, oy, delta;
+	int				 scroll_up; /* >0 up, <0 down */
+
+	mid_value = (screen_size_y(&data->screen) - 1) / 2;
+	scroll_up = data->cy - mid_value;
+	delta = abs(scroll_up);
+	oy = screen_hsize(data->backing) + data->cy - data->oy;
+
+	log_debug ("XXX %u %u %u %d %u", mid_value, oy, delta, scroll_up, data->oy);
+	if (scroll_up > 0 && data->oy >= delta) {
+		window_copy_scroll_up(wme, delta);
+		data->cy -= delta;
+	} else if (scroll_up < 0 && oy >= delta) {
+		window_copy_scroll_down(wme, delta);
+		data->cy += delta;
+	}
+
+	window_copy_update_selection(wme, 0, 0);
+	return (WINDOW_COPY_CMD_REDRAW);
+}
+
 static enum window_copy_cmd_action
 window_copy_cmd_cursor_up(struct window_copy_cmd_state *cs)
 {
@@ -2780,6 +2806,12 @@ static const struct {
 	  .clear = WINDOW_COPY_CMD_CLEAR_ALWAYS,
 	  .f = window_copy_cmd_scroll_down_and_cancel
 	},
+	{ .command = "scroll-middle",
+	  .minargs = 0,
+	  .maxargs = 0,
+	  .clear = WINDOW_COPY_CMD_CLEAR_ALWAYS,
+	  .f = window_copy_cmd_scroll_middle
+	},
 	{ .command = "scroll-up",
 	  .minargs = 0,
 	  .maxargs = 0,
-- 
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