RE: mouse-drag-and-drop-region

[Drew Adams]

FWIW, your mails are incomprehensible, to me.  A long
jumble, with (apparently) no newlines, just one long line.

> -----Original Message-----
> From: Tak Kunihiro [mailto:address@hidden
> Sent: Monday, November 20, 2017 5:30 AM
> To: address@hidden; Eli Zaretskii <address@hidden>; Alex
> <address@hidden>
> Cc: address@hidden; address@hidden
> Subject: Re: mouse-drag-and-drop-region
> 
> I revised mouse-drag-and-drop-region.  I'm sending replay
> tohttps://urldefense.proofpoint.com/v2/url?u=https-
> 3A__lists.gnu.org_archive_html_emacs-2Ddevel_2017-
> 2D11_msg00387.html&d=DwIGCQ&c=RoP1YumCXCgaWHvlZYR8PZh8Bv7qIrMUB65eapI_JnE
> &r=kI3P6ljGv6CTHIKju0jqInF6AOwMCYRDQUmqX22rJ98&m=7dAC1SXS16w1t_k03RCaPT4y
> x9Dj2w0sgzE9HrhKdH4&s=i_DYhSyvTHRfqzR6fFgh4X_gjdsRoGvmXF4Fq-z-
> eEU&e=,ChangeLog, and patch.* ChangeLog2017-11-21 Tak Kunihiro
> <address@hidden>        Improve comments and have two new
> options        * lisp/mouse.el (mouse-drag-and-drop-region): Make tooltip
> preview to be an option.  Have an option to make dragging cut among
> buffers.        (mouse-drag-and-drop-region-cut-among-buffer): New flag.
> When t, text is cut instead of copy when dragged among buffers.
> (mouse-drag-and-drop-region-show-tooltip): New flag.  When t, text is
> shown by a tooltip in a graphic display.* Replay> Did you ever consider
> using the "r" interactive switch instead of the> "e" one?I suppose you
> suggest something like below.  I cannot make this work.Thus this
> revision, I do not use "r" interactive switch.(defun mouse-drag-and-drop-
> region (event start and)  (interactive "e\nr")  ...)>>> (2) Activating
> the secondary overlay can be distracting and should>>>     be made
> optional (facultatively keeping the primary overlay in>>>     place
> provided (4) below is done).>>>> Region on the other window is not
> visible.  Thus original region>> should be hi-lighted somehow.  Since
> mouse-drag-and-drop-region is>> located on mouse.el, mouse-secondary-
> overlay was used.>> You mean that you highlight the original region with
> the secondary> overlay so that the overlay shows up on the target window
> as well and> the user is informed that dropping there might lead to say
> "dubious"> results?I think yes.  Also, since value-selection would be
> inserted before thepoint and mark, I thought it is handy to keep track
> where was theregion by an overlay.> I mean something like>> (defcustom
> mouse-drag-and-drop-region-show-secondary-overlay t ...)>> where setting
> this to nil means to just not show any overlay.  And> your code would
> have to accept that there is no secondary overlay at> the time of the
> drop.I found this takes significant time.  I skip to get rid of usage
> ofsecondary-overlay on this revision.>>> (3) Showing tooltips can be
> distracting and should be optional.>>>     Note also, that usurping
> tooltips this way may prevent them from>>>     showing interesting
> properties of the drop area like whether the>>>     text there is read
> only.  OTOH we might consider retaining>>>     properties of the text in
> (non-GTK) tooltips.>>> I would say>> (defcustom mouse-drag-and-drop-
> region-show-tooltip t)>> and never show a tooltip on text-only terminals
> even if this is t.OK.>>> (4) The (deactivate-mark) and (mouse-set-point
> event) trick to allow>>>     showing point the way ?mouse-drag-track?
> does can be distracting>>>     and should be made optional.>>>> I think
> that this is very related to 2, 3, and 5 (as you inferred).>> Yes.  It's
> irritating to drag a block cursor with the mouse.  Do you> know of any
> other applications which do such a thing?I cannot think of a way to show
> insert point besides (mouse-set-pointevent).  Do you suggest overlay-put
> "|" or change cursor-type to 'barduring drag?  I thought who prefers bar
> changes the default cursoranyway.  I did not revise code in this
> respect.>>> (5) The mouse pointer shape should take care of indicating
> the exact>>>     position where the drop occurs.  We should probably also
> signal>>>     whenever the current drop position is invalid.  This is
> IIUC>>>     usual practice on most window systems now.>>>> I think it is
> a good idea.>> We probably need to define additional cursors for this so
> it's not for> Emacs 26.I did not revise code in this aspect.>>> (7) IMO
> either cutting should be the default too when the drop>>>     occurs in a
> different buffer or copying would be the default and>>>     pressing the
> modifier should produce a cut instead.  The current>>>     behavior wants
> me to always keep in mind whether the target>>>     buffer is the same as
> the source buffer.  At least, this>>>     behavior should be made
> optional.>>>> Default behavior followed that of file browser on `drag' a
> file.>> Which file browser?Finder on macOS and File Explorer on Windows
> 10 behave like that way.>> Between the same volume (buffer), `drag' does
> `cut' instead of `copy'.>> I prefer current behavior as default but
> have>> no objection to have option something like>>   (defvar mouse-drag-
> and-drop-region-cut-hungry t)>> I would be more radical with>> (defcustom
> mouse-drag-and-drop-region-cut-or-copy t)>> where the values 'cut and
> 'copy would always categorically cut or copy> (unless the value of
> 'mouse-drag-and-drop-region' implies to copy> instead of cut) and t means
> your original behavior.A new option was created.  Now `cut' can be
> default even amongbuffers.(defvar mouse-drag-and-drop-region-cut-among-
> buffer nil  "When t, text is cut instead of copy when dragged among
> buffers.")>>> (8) Read-only text should be handled.  An attempt to drop
> text into>>>     a read-only area should be signalled to the user.  An
> attempt to>>>     cut text from a read-only text/buffer should be
> signalled as>>>     well.>>>>> For the latter, we copy text instead (cf
> C-w in read-only text).  So>>> I think this feature should behave
> similarly, at least by default.>>>>> I just noticed that the code does
> use ?kill-region? already.  This>>> has the side-effect of putting the
> text into the kill ring,>>> something which should be documented at
> least.  But I think the code>>> should rather use ?delete-region? instead
> with the behavior you>>> proposed.>>>> I suppose that you suggest to tell
> user more explicitly in echo area>> how he cannot change the text.>> The
> echo area should be avoided during tracking.  Think of users who> invoke
> 'mouse-drag-and-drop-region' on a frame without a minibuffer.OK.> I think
> that first of all you should use 'delete-region' instead of> 'kill-
> region' to avoid the above-mentioned side effect.  Then your> code should
> silently swallow any bugs for cutting from read-only> text provided
> 'kill-read-only-ok' is t.  For that purpose, simply> peruse the
> corresponding code from 'kill-region'.OK.  Now `delete-region' is used.>
> A final drop into read-only text should always give an error.  We> should
> be able to redeem that by providing a feedback in form of a> mouse cursor
> when the mouse is either over read-only text or no> buffer text at all.I
> revised only to give message.  I could not tell how to bringcondition-
> case to code.>> On an user perspective, operation `drag-and-drop-region'
> is a>> combination of `cut' and `paste'.  Thus text was killed instead
> of>> deleted.  How you think delete is more preferred?  I have no>>
> objection to document it.> IMO using 'kill-region' is an unexpected side
> effect.  If people> think differently, we could add yet another option
> like>> (defucstom mouse-drag-and-drop-region-cut-does-kill-region t)Now
> `delete-region' is used instead of `kill-region'.* Patchdiff --git
> a/lisp/mouse.el b/lisp/mouse.elold mode 100644new mode 100755index
> 17d1732..08f70d4--- a/lisp/mouse.el+++ b/lisp/mouse.el@@ -2361,6 +2361,12
> @@ text is copied instead of being cut."   :version "26.1"   :group
> 'mouse) +(defvar mouse-drag-and-drop-region-cut-among-buffer nil+  "When
> t, text is cut instead of copy when dragged among buffers.")++(defvar
> mouse-drag-and-drop-region-show-tooltip t+  "When t, text is shown by a
> tooltip in a graphic display.")+ (defun mouse-drag-and-drop-region
> (event)   "Move text in the region to point where mouse is dragged to.
> The transportation of text is also referred as `drag and drop'.@@ -
> 2369,64 +2375,98 @@ modifier key was pressed when dropping, and the value
> of the variable `mouse-drag-and-drop-region' is that modifier, the text
> is copied instead of being cut."   (interactive "e")-  (require
> 'tooltip)-  (let ((start (region-beginning))+  (let ((mouse-drag-and-
> drop-region-show-tooltip+         (and mouse-drag-and-drop-region-show-
> tooltip+              (display-multi-frame-p)+              (require
> 'tooltip)))+        (start (region-beginning))         (end (region-end))
> (point (point))         (buffer (current-buffer))         (window
> (selected-window))-        value-selection)+        no-modifier-on-drop+
> value-selection)    ; This remains nil when event was "click".
> (track-mouse-      ;; When event was click instead of drag, skip loop+
> ;; When event was "click" instead of "drag", skip loop.       (while
> (progn                (setq event (read-event))                (or
> (mouse-movement-p event)                    ;; Handle `mouse-autoselect-
> window'.                    (eq (car-safe event) 'select-window)))-
> (unless value-selection ; initialization+        ;; Obtain the text in
> region.  When the loop was skipped,+        ;; value-selection remains
> nil.+        (unless value-selection           (delete-overlay mouse-
> secondary-overlay)           (setq value-selection (buffer-substring
> start end))           (move-overlay mouse-secondary-overlay start end)) ;
> (deactivate-mark)-        (ignore-errors (deactivate-mark) ; care
> existing region in other window-                       (mouse-set-point
> event)-                       (tooltip-show value-selection)))-
> (tooltip-hide))-    ;; Do not modify buffer under mouse when "event was
> click",-    ;;                                       "drag negligible",
> or-    ;;                                       "drag to read-only".-
> (if (or (equal (mouse-posn-property (event-end event) 'face) 'region) ;
> "event was click"-            (member 'secondary-selection ; "drag
> negligible"-                    (mapcar (lambda (xxx) (overlay-get xxx
> 'face))-                            (overlays-at (posn-point (event-end
> event)))))-            buffer-read-only)-        ;; Do not modify buffer
> under mouse.+        (ignore-errors+          (deactivate-mark)         ;
> Maintain region in other window.+          (mouse-set-point event)+
> (when mouse-drag-and-drop-region-show-tooltip+            (tooltip-show
> value-selection))))+      ;; Check if modifier was pressed on drop.+
> (setq no-modifier-on-drop+            (not (member mouse-drag-and-drop-
> region (event-modifiers event))))+      (when mouse-drag-and-drop-region-
> show-tooltip (tooltip-hide)))+    ;; Do not modify buffer under mouse
> when event is "click", "drag+    ;; but negligible", or "drag to read-
> only".  Operation "drag but+    ;; negligible" is defined as drag-and-
> drop the text to+    ;; secondary-selection without modifier pressed.
> When pressed,+    ;; the text will be inserted to inside of secondary-
> selection.+    (if (or (equal (mouse-posn-property (event-end event)
> 'face) 'region) ; "click"+            (and (member 'secondary-selection ;
> "drag but negligible"+                         (mapcar (lambda (xxx)
> (overlay-get xxx 'face))+                                 (overlays-at
> (posn-point (event-end event)))))+                 no-modifier-on-drop)+
> buffer-read-only)           ; "drag to read-only"         (cond-
> ;; "drag negligible" or "drag to read-only", restore region.+         ;;
> Set back the original text as region on "drag but negligible"+         ;;
> or "drag to read-only".          (value-selection-          (select-
> window window) ; In case miss drag to other window+          (if buffer-
> read-only (message "Buffer is read-only")) ; (barf-if-buffer-read-only)+
> (select-window window) ; Select the source windows back on miss-drag to
> other window.           (goto-char point)           (setq deactivate-mark
> nil)           (activate-mark))-         ;; "event was click"+         ;;
> Move point within region on "click".          (t           (deactivate-
> mark)           (mouse-set-point event)))-      ;; Modify buffer under
> mouse by inserting text.+      ;; Intert the text to destination buffer
> under mouse.       (push-mark)       (insert value-selection)-      (when
> (not (equal (mark) (point))) ; on success insert+      ;; On success, set
> the text as region on destination buffer.+      (when (not (equal (mark)
> (point)))         (setq deactivate-mark nil)-        (activate-mark)) ;
> have region on destination-      ;; Take care of initial region on
> source.-      (if (equal (current-buffer) buffer) ; when same buffer-
> (let (deactivate-mark) ; remove text-            (unless (member mouse-
> drag-and-drop-region (event-modifiers event))-              (kill-region
> (overlay-start mouse-secondary-overlay)-
> (overlay-end mouse-secondary-overlay))))-        (let ((window1
> (selected-window))) ; when beyond buffer-          (select-window
> window)-          (goto-char point) ; restore point on source window-
> (activate-mark) ; restore region+        (activate-mark))+      ;; Set
> back the original text as region or delete the original+      ;; text on
> source buffer.+      (if (equal (current-buffer) buffer)+          ;;
> When source buffer and destination buffer are the same,+          ;;
> remove the original text.+          (let (deactivate-mark)+
> (if no-modifier-on-drop+                (delete-region (overlay-start
> mouse-secondary-overlay)+                               (overlay-end
> mouse-secondary-overlay))))+        ;; When source buffer and destination
> buffer are different,+        ;; keep (set back the original text as
> region) or remove the+        ;; original text.+        (let ((window1
> (selected-window)))+          (select-window window)   ; Select window
> with source buffer.+          (goto-char point) ; Move point to the
> original text on source buffer.+          (if (or (if no-modifier-on-
> drop+                      (not mouse-drag-and-drop-region-cut-among-
> buffer)+                    mouse-drag-and-drop-region-cut-among-buffer)+
> buffer-read-only)+              ;; Set back the original text as region
> on source buffer+              ;; like operation `copy'.+
> (progn+                (if buffer-read-only (message "Source is read-
> only")) ; (barf-if-buffer-read-only)+                (activate-mark))+
> ;; Remove the original text from source buffer like+            ;;
> operation `cut'.+            (delete-region (overlay-start mouse-
> secondary-overlay)+                           (overlay-end mouse-
> secondary-overlay)))           (select-window window1))))     (delete-
> overlay mouse-secondary-overlay)))