From e22546c56a281c1c79ac76c196e69b9db2cb61f1 Mon Sep 17 00:00:00 2001
From: pagedown <pg.dn@outlook.com>
Date: Sat, 5 Feb 2022 20:02:24 +0800
Subject: [PATCH] Add arguments to get the first and last line of text for
 launch command

---
 docs/changelog.rst | 4 ++++
 docs/launch.rst    | 6 ++++++
 kitty/launch.py    | 6 +++++-
 3 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/docs/changelog.rst b/docs/changelog.rst
index 17d75b4ae..00f1fe932 100644
--- a/docs/changelog.rst
+++ b/docs/changelog.rst
@@ -99,6 +99,10 @@ Detailed list of changes
 - A new action :ac:`scroll_prompt_to_bottom` to move the current prompt
   to the bottom, filling in the window from the scrollback (:pull:`4634`)
 
+- Add two special arguments ``@first-line-on-screen`` and ``@first-line-on-screen``
+  for the :doc:`launch <launch>` command to be used for pager positioning. 
+  (:iss:`4462`)
+
 0.24.2 [2022-02-03]
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
diff --git a/docs/launch.rst b/docs/launch.rst
index bdda8c9b4..47f6d65b5 100644
--- a/docs/launch.rst
+++ b/docs/launch.rst
@@ -95,6 +95,12 @@ the command line:
 ``@cursor-y``
     replaced by the current cursor y position with 1 being the topmost cell
 
+``@first-line-on-screen``
+    replaced by the first line on screen. Can be used for pager positioning.
+
+``@last-line-on-screen``
+    replaced by the last line on screen. Can be used for pager positioning.
+
 
 For example::
 
diff --git a/kitty/launch.py b/kitty/launch.py
index f8b4ee932..57284a424 100644
--- a/kitty/launch.py
+++ b/kitty/launch.py
@@ -397,7 +397,7 @@ def launch(
                 elif x == '@line-count':
                     if 'lines' in pipe_data:
                         x = str(pipe_data['lines'])
-                elif x in ('@cursor-x', '@cursor-y', '@scrolled-by'):
+                elif x in ('@cursor-x', '@cursor-y', '@scrolled-by', '@first-line-on-screen', '@last-line-on-screen'):
                     if active is not None:
                         screen = active.screen
                         if x == '@scrolled-by':
@@ -406,6 +406,10 @@ def launch(
                             x = str(screen.cursor.x + 1)
                         elif x == '@cursor-y':
                             x = str(screen.cursor.y + 1)
+                        elif x == '@first-line-on-screen':
+                            x = str(screen.visual_line(0) or '')
+                        elif x == '@last-line-on-screen':
+                            x = str(screen.visual_line(screen.lines - 1) or '')
             final_cmd.append(x)
         exe = which(final_cmd[0])
         if exe: