The `button-down?' method returns #t only for events that correspond to a button press. The `get-left-down', etc., methods report whether the button is held down during a given event.
(This is confusing, but we inherited the behavior originally from wxWidgets years ago.) At Mon, 05 Sep 2011 16:24:38 +0200, Marijn wrote: > -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA1 > > Hi list, > > the following program defines a canvas%-derived that catches mouse > events and prints the drag events. Unfortunately I was unable to make > it report any drag events. It does report motion events and left-click > events when generated by me (currently turned off). Is this a bug or > am I doing something wrong here? > > Marijn > > > #lang racket/gui > > (define (handle-drag event) > (print event)) > > (define (handle-motion event) > #f) > > (define (handle-left-down event) > #f #;(print event)) > > (define drawtest% > (class canvas% > (init parent) > (super-new (parent parent)) > > (define/override (on-event event) > (let ((type (send event get-event-type))) > (case type > ((motion) > (if (send event button-down?) > (handle-drag event) > (handle-motion event))) > ((left-down) > (handle-left-down event)) ))) > > )) > > (define root (new frame% (label "Draw Test"))) > > (new drawtest% > (parent root) > (min-width 100) (min-height 100) > (style '(border) #;'(combo control-border))) > > (send root show #t) > -----BEGIN PGP SIGNATURE----- > Version: GnuPG v2.0.18 (GNU/Linux) > Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ > > iEYEARECAAYFAk5k26YACgkQp/VmCx0OL2zsvgCfbRwmpapGh1EL3AdL+8SN7DV+ > sYcAoI81YwOnJN7R03PpJt+IyH95h3Vu > =Zx+r > -----END PGP SIGNATURE----- > _________________________________________________ > For list-related administrative tasks: > http://lists.racket-lang.org/listinfo/users _________________________________________________ For list-related administrative tasks: http://lists.racket-lang.org/listinfo/users
