canvas

[Jason Miller]

Hi Igor,

I'd never used canvas before, but I took the tutoial here:
 https://tkdocs.com/tutorial/canvas.html

And ported it to lisp:

(defun sketch ()
  (ltk:with-ltk ()
    (let ((c (make-instance 'ltk:canvas))
	  lastx
	  lasty)
      (flet ((add-line (x y)
	       (make-instance 'ltk:canvas-line 
			      :canvas c
			      :coords (list lastx lasty x y))
	       (setf lastx x
		     lasty y)))
      (ltk:grid c 0 0 :sticky "nwes")
      (ltk:grid-columnconfigure ltk:*tk* 0 :weight 1)
      (ltk:grid-rowconfigure ltk:*tk* 0 :weight 1)
      (ltk:bind c "<1>" (lambda (e)
			  (setf lastx (ltk:event-x e)
				lasty (ltk:event-y e))))
      (ltk:bind c "<B1-Motion>" (lambda (e)
				  (add-line
				   (ltk:event-x e)
				   (ltk:event-y e))))))))

Hope that helps,
Jason

On Sun, 8 Nov 2020 22:13:26 -0800, Jason Miller <jason at milr.com> wrote:
> I think you want something like this?
> 
> (ltk:with-ltk ()
>   (let ((c (make-instance 'ltk:canvas)))
>     (ltk:pack c)
>     (make-instance 'ltk:canvas-line :coords '(20 20 40 40) :canvas c)))
> 
> 
> On Sat, 7 Nov 2020 17:18:23 -0500, igor denisov <saufesma at gmail.com> wrote:
> > Hi there,
> > 
> > I cannot figure out how to use canvas. I JUST DO NOT KNOW WHERE TO
> > LOOK FOR THE ANSWER
> > 
> > LTK> (let* (;;(f (make-instance 'frame))
> >        (c (make-instance 'canvas :width WIDTH :height HEIGHT))
> >        (line (create-line c 20 20 40 40))
> >        ;;(pack f)
> >        (pack c)
> >        ;;(itemconfigure c line arrow first) ;; HOW TO MAKE IT WORK
> > !!!!!!!!!!!!!!!
> >        ))
> > ; in:
> > ;      LET* ((C (MAKE-INSTANCE 'CANVAS :WIDTH WIDTH :HEIGHT HEIGHT))
> > ;        (LINE (CREATE-LINE C 20 20 40 40)) (PACK C))
> > ;     (LTK:CREATE-LINE LTK::C 20 20 40 40)
> > ;
> > ; caught STYLE-WARNING:
> > ;   The function was called with five arguments, but wants exactly two.
> > 
> > ;     (LET* ((LTK::C
> > ;             (MAKE-INSTANCE 'LTK:CANVAS :WIDTH LTK::WIDTH :HEIGHT LTK::HEIGHT))
> > ;            (LTK::LINE (LTK:CREATE-LINE LTK::C 20 20 40 40))
> > ;            (LTK:PACK LTK::C))
> > ;       )
> > ;
> > ; caught STYLE-WARNING:
> > ;   The variable LINE is defined but never used.
> > ;
> > ; caught STYLE-WARNING:
> > ;   The variable PACK is defined but never used.
> > ;
> > ; compilation unit finished
> > ;   caught 3 STYLE-WARNING conditions
> > ; Evaluation aborted on #<SB-INT:SIMPLE-PROGRAM-ERROR "invalid number
> > of arguments: ~S" {1003704743}>.
> > 
> > 
> > Here is another one.
> > 
> > If you run the following you get a strange error
> > 
> > (defun 0-ltk-test ()
> >              (with-ltk (:serve-event t)
> >                (let ((sc (make-instance 'scrolled-canvas)))
> >                (create-line sc '(10 10 20 20))
> >                      (pack sc :expand 1 :fill :both)
> >                      )))
> > 
> > The value
> >   NIL
> > is not of type
> >   STREAM
> > when binding STREAM
> >    [Condition of type TYPE-ERROR]
> > 
> > BEST
> > 
> > On 11/7/20, igor denisov <saufesma at gmail.com> wrote:
> > > Hi there,
> > >
> > > Here is another one.
> > >
> > > If you run the following you get a strange error
> > >
> > > (defun 0-ltk-test ()
> > >              (with-ltk (:serve-event t)
> > >                (let ((sc (make-instance 'scrolled-canvas)))
> > > 	       (create-line sc '(10 10 20 20))
> > >                      (pack sc :expand 1 :fill :both)
> > >                      )))
> > >
> > > The value
> > >   NIL
> > > is not of type
> > >   STREAM
> > > when binding STREAM
> > >    [Condition of type TYPE-ERROR]
> > >
> > > On 11/7/20, igor denisov <saufesma at gmail.com> wrote:
> > >> I cannot figure out how to use canvas. I JUST DO NOT KNOW WHERE TO LOOK
> > >> FOR
> > >>
> > >> LTK> (let* (;;(f (make-instance 'frame))
> > >>        (c (make-instance 'canvas :width WIDTH :height HEIGHT))
> > >>        (line (create-line c 20 20 40 40))
> > >>        ;;(pack f)
> > >>        (pack c)
> > >>        ;;(itemconfigure c line arrow first) ;; HOW TO MAKE IT WORK
> > >> !!!!!!!!!!!!!!!
> > >>        ))
> > >> ; in:
> > >> ;      LET* ((C (MAKE-INSTANCE 'CANVAS :WIDTH WIDTH :HEIGHT HEIGHT))
> > >> ;        (LINE (CREATE-LINE C 20 20 40 40)) (PACK C))
> > >> ;     (LTK:CREATE-LINE LTK::C 20 20 40 40)
> > >> ;
> > >> ; caught STYLE-WARNING:
> > >> ;   The function was called with five arguments, but wants exactly two.
> > >>
> > >> ;     (LET* ((LTK::C
> > >> ;             (MAKE-INSTANCE 'LTK:CANVAS :WIDTH LTK::WIDTH :HEIGHT
> > >> LTK::HEIGHT))
> > >> ;            (LTK::LINE (LTK:CREATE-LINE LTK::C 20 20 40 40))
> > >> ;            (LTK:PACK LTK::C))
> > >> ;       )
> > >> ;
> > >> ; caught STYLE-WARNING:
> > >> ;   The variable LINE is defined but never used.
> > >> ;
> > >> ; caught STYLE-WARNING:
> > >> ;   The variable PACK is defined but never used.
> > >> ;
> > >> ; compilation unit finished
> > >> ;   caught 3 STYLE-WARNING conditions
> > >> ; Evaluation aborted on #<SB-INT:SIMPLE-PROGRAM-ERROR "invalid number
> > >> of arguments: ~S" {1003704743}>.
> > >>
> > >> BEST
> > >>
> > >
> > 
>