From 48159c16b58af959555ced5cbd510835db5ea17b Mon Sep 17 00:00:00 2001
From: Gregory Heytings <gregory@heytings.org>
Date: Thu, 13 Jan 2022 10:31:43 +0200
Subject: Undelete deleted frames.
* lisp/frame.el (undelete-frame): New command.
(undelete-frame--handle-delete-frame): New auxiliary function.
(undelete-frame--deleted-frames): New auxiliary variables.
(undelete-frame-mode): New minor mode.
(ctl-x-5-map): Bind the new command.
* etc/NEWS: Document the new command and minor mode.
* src/frame.c (Fdelete_frame): Update docstring, and mention the
minor mode.
* lisp/menu-bar.el (menu-bar-file-menu): Add an entry for the
new command.
* doc/emacs/frames.tex (Frame Commands): Document the new command
and minor mode.
See bug#51883.
---
lisp/frame.el | 75 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 75 insertions(+)
(limited to 'lisp/frame.el')
diff --git a/lisp/frame.el b/lisp/frame.el
index 62b73f3157b..599ffe591a5 100644
--- a/lisp/frame.el
+++ b/lisp/frame.el
@@ -2529,6 +2529,80 @@ deleting them."
(if iconify (iconify-frame this) (delete-frame this)))
(setq this next))))
+(eval-when-compile (require 'frameset))
+
+(defvar undelete-frame--deleted-frames nil
+ "Internal variable used by `undelete-frame--handle-delete-frame'.")
+
+(defun undelete-frame--handle-delete-frame (frame)
+ "Save the configuration of frames deleted with `delete-frame'.
+Only the 16 most recently deleted frames are saved."
+ (when (frame-live-p frame)
+ (setq undelete-frame--deleted-frames
+ (cons
+ (cons
+ (display-graphic-p)
+ (frameset-save
+ (list frame)
+ ;; When the daemon is started from a graphical
+ ;; environment, TTY frames have a 'display' parameter set
+ ;; to the value of $DISPLAY (see the note in
+ ;; `server--on-display-p'). Do not store that parameter
+ ;; in the frameset, otherwise `frameset-restore' attempts
+ ;; to restore a graphical frame.
+ :filters (if (display-graphic-p)
+ frameset-filter-alist
+ (cons '(display . :never)
+ frameset-filter-alist))))
+ undelete-frame--deleted-frames))
+ (if (> (length undelete-frame--deleted-frames) 16)
+ (setq undelete-frame--deleted-frames
+ (butlast undelete-frame--deleted-frames)))))
+
+(define-minor-mode undelete-frame-mode
+ "Enable the `undelete-frame' command."
+ :group 'frames
+ :global t
+ (if undelete-frame-mode
+ (add-hook 'delete-frame-functions
+ #'undelete-frame--handle-delete-frame -75)
+ (remove-hook 'delete-frame-functions
+ #'undelete-frame--handle-delete-frame)
+ (setq undelete-frame--deleted-frames nil)))
+
+(defun undelete-frame (&optional arg)
+ "Undelete a frame deleted with `delete-frame'.
+Without a prefix argument, undelete the most recently deleted
+frame.
+With a numerical prefix argument ARG between 1 and 16, where 1 is
+most recently deleted frame, undelete the ARGth deleted frame.
+When called from Lisp, returns the new frame."
+ (interactive "P")
+ (if (not undelete-frame-mode)
+ (user-error "Undelete-Frame mode is disabled")
+ (if (consp arg)
+ (user-error "Missing deleted frame number argument")
+ (let* ((number (pcase arg ('nil 1) ('- -1) (_ arg)))
+ (frames (frame-list))
+ (frameset (nth (1- number) undelete-frame--deleted-frames))
+ (graphic (display-graphic-p)))
+ (if (not (<= 1 number 16))
+ (user-error "%d is not a valid deleted frame number argument"
+ number)
+ (if (not frameset)
+ (user-error "No deleted frame with number %d" number)
+ (if (not (eq graphic (car frameset)))
+ (user-error
+ "Cannot undelete a %s display frame on a %s display"
+ (if graphic "non-graphic" "graphic")
+ (if graphic "graphic" "non-graphic"))
+ (setq undelete-frame--deleted-frames
+ (delq frameset undelete-frame--deleted-frames))
+ (frameset-restore (cdr frameset))
+ (let ((frame (car (seq-difference (frame-list) frames))))
+ (when frame
+ (select-frame-set-input-focus frame)
+ frame)))))))))
;;; Window dividers.
(defgroup window-divider nil
@@ -2873,6 +2947,7 @@ See also `toggle-frame-maximized'."
(define-key ctl-x-5-map "o" #'other-frame)
(define-key ctl-x-5-map "5" #'other-frame-prefix)
(define-key ctl-x-5-map "c" #'clone-frame)
+(define-key ctl-x-5-map "u" #'undelete-frame)
(define-key global-map [f11] #'toggle-frame-fullscreen)
(define-key global-map [(meta f10)] #'toggle-frame-maximized)
(define-key esc-map [f10] #'toggle-frame-maximized)
--
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