Re: Drag-and-Drop with guile-gnome?

[steve tell]

On Fri, 25 May 2007, Andy Wingo wrote:

> Hey Steve,
>
> On Fri, 2007-05-25 at 00:32 -0400, steve tell wrote:
> > Is it possible to do Drag-and-Drop with guile-gnome-2.15.9x?
> > Does anyone have any examples?
>
> It turns out yesterday's release shouldn't be used because I borked
> something with Cairo -- will put out a fix later today.
>
> But!
>
> My photoblogger app still works I think,
> http://wingolog.org/software/photoblogger/. There is some dnd code
> there, but it doesn't always work. You might have to do some hacking :)

Thanks!
After installing guile-lib-0.1.3, your photoblogger runs well enough to 
serve as an example of the "drop" part, but it doesn't provide sources 
that can be dragged to its own or another app's drop-site.


With that as a guide, I'm crafting a simpler example, testdnd.scm.

gtk-drag-dest-set works, and interoperates with the 
gtk+-2.4.14/tests/testdnd.c I had lying around.

But I think gtk-drag-source-set is missing a needed entry in 
guile-gnome-platform-*/gtk/gnome/overrides/gtk.defs
The def in defs/gnome/defs/gtk.defs:

(define-function gtk_drag_source_set
  (c-name "gtk_drag_source_set")
  (return-type "none")
  (parameters
    '("GtkWidget*" "widget")
    '("GdkModifierType" "start_button_mask")
    '("const-GtkTargetEntry*" "targets")
    '("gint" "n_targets")
    '("GdkDragAction" "actions")
  )
)

has arguments of the pattern of an array pointer followed by an integer 
specifying the length of the array.  Am I correct in assuming that all 
functions like that need to have an override def specifying the 
scheme-friendly way of passing such a list argument?  There seem to be 
others like that too.

Rather than further hacking 2.15.90, I guess I'll try to upgrade g-wrap 
and then guile-gnome-platform.

Steve





#!/usr/bin/guile -s
!#
; testdnd - demonstrate fundamental drag-and-drop.
; Modeled after gtk+-2.4.14/tests/testdnd.c


(debug-enable 'debug  'backtrace)
(read-enable 'positions)

(use-modules (gnome-0)
              (gnome gtk)
)

(define (label-drag-data-received w drag-context x y selection-data info t)
  (let* ((data (gtk-selection-data-get-as-string selection-data)))
    (format #t "received in label: ~s\n" data)
    (gtk-drag-finish drag-context #t #t)))

(define (source-drag-data-get w drag-context x y selection-data info t)
  (format #f "source-drag-data-get ~s ~s\n" drag-context info)
  (gtk-selection-data-set-as-string selection-data "drop data")
)

(define (source-drag-data-delete w drag-context)
  (format #f "delete the drag-data!\n")
)

(define (app)
  (let* ((window (make <gtk-window> #:type 'toplevel))
         (table (make <gtk-table>
                  #:n-columns 2 #:n-rows 2 #:homogeneous #f
                  #:border-width 5 #:row-spacing 5 #:row-spacing 10))
         (droplabel (make <gtk-label> #:label "Drop here"))
         (poplabel (make <gtk-label> #:label "Someday: Popup"))
         (dragbutton (make <gtk-button> #:label "Drag This"))
         )

    (gtk-window-set-default-size window 300 200)
    (gtk-container-add window table)

    (attach table droplabel
            0 1  0 1  '(fill expand) '(fill expand) 0 0)
    (gtk-drag-dest-set droplabel 'all '("text/plain") 'copy)
    (connect droplabel 'drag-data-received label-drag-data-received)

    (attach table poplabel
            1 2  1 2  '(fill expand) '(fill expand) 0 0)

    (attach table dragbutton
            0 1  1 2  '(fill expand) '(fill expand) 0 0)

; doesn't work, at least with guile-gnome-platform 2.15.90
;   (gtk-drag-source-set dragbutton  #f '("text/plain") 'copy)

;   (gtk-drag-source-set-icon dragbutton  ) ;TODO figure out the guileish args
    (connect dragbutton 'drag-data-get source-drag-data-get)
    (connect dragbutton 'drag-data-delete source-drag-data-delete)

    ; TODO: trashcan pixmap and open/closed handling

    (gtk-widget-show-all window)

    (gtk-main)))

(app)