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Howdy,

I found myself wondering how hard it would be to make an X client which plays nice with select-and-paste (as seen by all the other X clients out there). The answer seems to be "quite hard", but here's a step along the road: a translation of some C test code, yielding a proof-of-concept clipboard client. Pastes both to and from the client work: a paste of text to the client yields printed messages to the lisp's standard output, and pastes while the client owns PRIMARY (left-click in the window) cause a silly piece of text to be pasted.

Christophe

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;;; This is a pretty direct translation of the Xlib selection test ;;; program by Tor Andersson found at ;;; http://ghostscript.com/~tor/repos/Klipp/x11clipboard.c, with ;;; minor enhancements: ;;; ;;; * gdk requestors apparently unconditionally request UTF8_STRING ;;; selections without checking the TARGETS list of the selection ;;; owner -- and apparently even never request anything else. This ;;; seems to be in contradiction with the freedesktop.org draft ;;; specification at ;;; http://www.pps.jussieu.fr/~jch/software/UTF8_STRING/UTF8_STRING.text ;;; (linked from http://freedesktop.org/Standards), but this is ;;; the real world and we have to live in it. It would be nice if ;;; someone in the freedesktop community could resolve this. ;;; ;;; * the original C code, in the XSendEvent call, has an event mask ;;; of SelectionNotify. SelectionNotify is not an event mask at ;;; all, however: but the code works "by accident" because ;;; SelectionNotify happens to have value 31, which has enough bits ;;; flipped on that most clients select on at least one of those ;;; events. This bug is fixed below. ;;; ;;; As ever with these things, the divisions in intellectual property ;;; between the writer of the original C program, Tor Andersson ;;; (contactable at tor [dot] andersson [at] gmail [dot] com) and the ;;; translator (Christophe Rhodes, csr21 [at] cam [dot] ac [dot] uk) ;;; are murky, probably depend on jurisdiction, and in addition for ;;; such a small work are essentially trivial. To set peoples' minds ;;; at ease, Tor wishes this information to be disseminated as widely ;;; as possible.

;;; Copyright (c) 2004, Christophe Rhodes ;;; ;;; Permission is hereby granted, free of charge, to any person ;;; obtaining a copy of this software and associated documentation ;;; files (the "Software"), to deal in the Software without ;;; restriction, including without limitation the rights to use, copy, ;;; modify, merge, publish, distribute, sublicense, and/or sell copies ;;; of the Software, and to permit persons to whom the Software is ;;; furnished to do so, subject to the following conditions: ;;; ;;; The above copyright notice and this permission notice shall be ;;; included in all copies or substantial portions of the Software. ;;; ;;; THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, ;;; EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF ;;; MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND ;;; NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT ;;; HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, ;;; WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, ;;; OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER ;;; DEALINGS IN THE SOFTWARE.

(defpackage "CLIPBOARD" (:use "CL" "XLIB") (:export "MAIN"))

(in-package "CLIPBOARD")

;;; This is "traditional" XLIB style; I don't really know if it's the ;;; best way -- in developing this program, style of XLIB programming ;;; was secondary to achieving First Paste. (defvar *window*) (defvar *time*) (defvar *display*)

(defun ownselect () (format t "~&> set-selection-owner~%") (finish-output) (set-selection-owner *display* :primary *window* *time*) (unless (eq *window* (selection-owner *display* :primary)) (write-string "failed to own primary")))

(defun deselect () (format t "~&> unset-selection-owner~%") (finish-output) (set-selection-owner *display* :primary nil *time*) (unless (eq nil (selection-owner *display* :primary)) (write-string "failed to disown primary")))

(defun ask-paste () (format t "~&! deleting properties on window~%") (finish-output) (delete-property *window* :aeclip-target) (delete-property *window* :aeclip-string) (delete-property *window* :aeclip-utf8_string) (delete-property *window* :aeclip-text) (format t "~&> convert-selection TARGETS~%") (finish-output) (convert-selection :primary :targets *window* :aeclip-target) (format t "~&> convert-selection STRING~%") (finish-output) (convert-selection :primary :string *window* :aeclip-string) (format t "~&> convert-selection UTF8_STRING~%") (finish-output) (convert-selection :primary :utf8_string *window* :aeclip-utf8_string) (format t "~&> convert-selection TEXT~%") (finish-output) (convert-selection :primary :text *window* :aeclip-text) nil)

(defun recv-paste (property) (multiple-value-bind (data name format) (get-property *window* property) (format t "~&< get-prop ~S " name) (case format (32 (format t "[~{~S~^,~}]" (mapcar (lambda (x) (atom-name *display* x)) data))) (8 (format t "~S" (map 'string 'code-char data))) (t (format t "format=~S data=~S" format data))) (format t "~%") (finish-output) (delete-property *window* property)))

(defun send-copy (selection target property requestor time) (case target ;; we are being a little liberal in what we accept here: no ;; requestor should ask us for a UTF8_STRING selection because we ;; don't advertise the capability (see the TARGETS clause below). ;; However, Xt-based requestors appear not to query TARGETS, ;; instead trying UTF8_STRING, COMPOUND_TEXT and STRING in order; ;; Gdk-based requestors don't query TARGETS either, trying just ;; UTF8_STRING (and giving up if the selection owner returns a ;; null property). So pretend that we can send UTF8_STRING ;; selections. ((:string :utf8_string) (format t "~&> sending text data~%") (finish-output) (change-property requestor property "Hello, World (from the CLX clipboard)!" target 8 :transform #'char-code)) (:targets (format t "~&> sending targets list~%") (finish-output) (change-property requestor property '(:targets :string) target 32 :transform (lambda (x) (intern-atom *display* x)))) (t (format t "~&> sending none~%") (finish-output) (setf property nil))) (send-event requestor :selection-notify (make-event-mask :button-press :property-change) :selection selection :target target :property property :time time :event-window requestor :window requestor))

(defun main () (let* ((*display* (open-default-display)) (screen (display-default-screen *display*)) (*window* (create-window :parent (screen-root screen) :x 10 :y 10 :width 200 :height 200 :event-mask (make-event-mask :button-press :property-change)))) (map-window *window*) (display-finish-output *display*) (event-case (*display*) (:button-press (code time) (format t "~&ButtonPress~%") (finish-output) (case code (1 (setf *time* time) (ownselect)) (2 (ask-paste)) (3 (deselect)))) (:client-message () (format t "~&ClientMessage~%") (finish-output)) (:selection-clear (selection) (format t "~&SelectionClear ~S~%" selection) (finish-output)) (:selection-notify (selection target property) (format t "~&SelectionNotify ~S ~S ~S~%" selection target property) (finish-output) (unless (eq property nil) (recv-paste property)) (display-finish-output *display*)) (:selection-request (selection target property requestor time) (format t "~&SelectionRequest ~S ~S ~S~%" selection target property) (finish-output) (send-copy selection target property requestor time) (display-finish-output *display*)) (:property-notify (atom state) (format t "~&PropertyNotify ~S ~S~%" atom state) (finish-output)))))