FOXEA@VTCC1.BITNET (10/24/89)
From: VTCC1::RAMAKRISH 23-OCT-1989 15:40:59.86
To: FOXEA
CC: RAMAKRISH
Subj: PROBLEMS WITH WIDGETS - DOCUMENTATION.
Subject : PROBLEMS WITH X-WINDOWS.
*
Submitted by : RAMAKRISHNAN S and NAGANAND DORASWAMY.
*
Problem ONE :
1) We require to use a widget upon which we can draw
graphics pictures.
2) We also need to make scrolling possible: one elegant
way to do this is by making the 'graphics' widget the
child of a VIEWPORT widget (widget automatically
provides scrollbars if its child were larger than its
frame).
3) None of the widgets provided by X11 seem fit for this
purpose:
COMMAND widget : For panel buttons.
LABEL widget : Uneditable messages.
DIALOG widget : For accepting strings.
BOX widget : A frame for enclosing other widgets.
FORM widget : Same as BOX except that it provides
an ordering for placement.
GRIP widget : Handling pointer events.
VPaned : A more sophisticated framework tha
n BOX & FORM for holding other
subwindows.
TEXT (string): To display EDITABLE (optional)/
APPENDABLE string information.
TEXT (file) : To display a file with options to
edit/append.
We just need a widget on which we can paint using the
XDraw... functions of X11. We know how to take care of
scrolling.
We tried to come over the problem by extracting the
window of a widget (say the BOX widget) and drawing on
this window (this window becomes the 'Drawable' required
by the XDraw... functions) : we got some funny results;
the drawing never appears and at times the even the widget
itself doesn't appear.
The X11 manual on widgets does say that widgets can be used
for graphics purposes : doesn't say which.
I hope I've made the problem clear. (essentially the stmnt
#1 of the problem summarizes the problem).
Problem TWO :
There's another\ minor problem :
At times,instantiations of widgets seem to completely ignore the
argument values specified by the widget defn given by the
program : the default values from the resource database
are then consulted. We have seen this happening esp with
creation of :
1) Viewports with scrollbars (forcing the scrollbar
creation is completely ignored).
2) Shell widgets for popups : although we specify the
XtNminHeight, XtNmaxHeight, XtNminwidth and
XtNmaxwidth values in the program (we do this
very correctly , as per the X11 syntax : I assure
you) , at the time of widget realization, the
dimensions remain zero , so that a runtime occurs.
Since we 're interested in participating in the demo,
and since the problem #1 is essentially blocking our
progress, I am very eager to find a soln for this
ASAP.
Thank You.
Ramakrishnan S.
Naganand Doraswamy.
Date : 23-Oct.