Aviv Gladman wrote:
>
> Writing a GUI in IDL 5 (SunOS 5) and would like to be able to process
> keyboard interrupts from any window (as opposed to from stdin). Such an
> operation would be trivial in C/C++, but I can't seem to find any way of
> getting IDL to recognize that a key has been pressed while the mouse
> focus is on a draw widget, for example.Being unable to create widget
> hotkeys is, IMO, a ridiculous limitation, so I'm sure there must be a way
> to do it. Any ideas? Please respond via e-mail, if possible (mail reader
> is *very* slow).
>
> Thanks,
>
> Aviv S. Gladman, MASc
As David points out, this functionality is not built in. But if you're
willing to settle for a hack, I have come up with one. The mouse focus
and keyboard focus are independent, which you can use to your
advantage. It's very simple, really. All you need to do is hide a
widget_text widget with all_events set *underneath* your draw widget,
and ensure its input focus is set when appropriate in the event
handler. I have simply set focus every time through, but a better
technique would do so only when entering the window, or when a button on
the draw window is clicked (motion events do not remove the input
focus), etc. I've tested this on Linux IDL v5.0, but no guarantees are
made for other platforms (it *should* work on any of them though).
A few suggestions:
If you want the hotkeys active only while the cursor is inside the draw
widget, you must enable widget tracking for the draw widget. On
entering the window, set the input focus to the hidden text widget. On
leaving the window, set it to something else (maybe just a "dummy" text
widget which also lives under the draw widget but has only EDITABLE
set). Conversely, you could just turn off the text events for the
hidden widget with widget_control, hidden, ALL_TEXT_EVENTS=0, turning
events back on for reentry. This method will cause a beep if the user
presses a key while outside the draw widget (maybe you'd want that).
The method of setting focus to the "dummy" widget (with EDITABLE
enabled) avoids this beep. The ALL_TEXT_EVENTS method might look like:
widget_control, hidden, ALL_TEXT_EVENTS=ev.enter.
This technique is in no way tied to a draw widget and can be used in any
widget application (as long as you can hide the text widget somewhere),
but it will be more difficult when there are other text entry widgets...
you must ensure your input focus returns to the hidden text widget when
appropriate, which may become annoying for the user -- he might have to
click to enter text each time. Encapsulating the functionality (by
turning on and off as suggested for draw widgets) to those parts of the
application for which it is useful might help.
The ability to turn the hotkeys on and off simply by changing the input
focus can be put to good use... for instance, you could disable hotkeys
when a click-and-drag operation is being done (that's actually done for
you, since button presses change the input focus). But keep in mind
that on most systems, the user can change the input_focus with the TAB
key, so be careful, and use ALL_TEXT_EVENTS=0 when a danger exists. You
could even employ KBRD_FOCUS events for this purpose.
Hope this proves useful.
JD
Here's the code:
pro testhotkey_event,ev
stash=widget_info(ev.handler,/CHILD)
widget_control, stash, get_uvalue=state,/NO_COPY
name=tag_names(ev,/structure_name)
case name of
'WIDGET_TEXT_CH': $
begin
erase
xyouts,.5,.5,/NORMAL,'Character: '+string(ev.ch)+'('+ $
strtrim(fix(ev.ch),2)+')',ALIGN=.5,CHARSIZE=3.0,COLOR=!D.N_C OLORS/2
ls=['qQxX']
wh=where(byte(ls) eq ev.ch,cnt)
if cnt ne 0 then begin ;quit
widget_control, ev.top,/DESTROY
return
endif
end
else: $ ;draw event
begin
types=['button event','motion event']
erase
seed=state.sd
xyouts, .5,.5,/NORMAL,types[(ev.type-1)>0], ALIGNMENT=.5, $
COLOR=fix(!d.n_colors*randomu(seed)),CHARSIZE=3.0
state.sd=seed
end
endcase
widget_control, state.hidden, /INPUT_FOCUS
widget_control, stash,set_uvalue=state,/NO_COPY
return
end
pro testhotkey
loadct, 6
base=widget_base(/COLUMN)
label=widget_label(base,value='Hot Key Test')
b=widget_base(base)
sz=500
draw=widget_draw(b,xsize=sz,ysize=sz,/motion,/button)
hidden=widget_text(b,scr_xsize=1,scr_ysize=1,/ALL,FRAME=0)
info={hidden:hidden,sd:0}
widget_control, label,set_uvalue=info
widget_control, b,/REALIZE
widget_control, draw,get_value=win & wset,win
XManager, 'testhotkey',base
return
end
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