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From: Joseph Rosevear on 6 Mar 2010 23:50
Hello to you in comp.soft-sys.wxwindows,

I'm new to this news group and also new to X programming. Let me
introduce myself. I know a little C programming, and I'm somewhat
skilled in Bash. I've been a Slackware Linux user for about ten years.

I came here hoping to learn a little by getting help with a problem. I
found an example Athena widgets program. The source is called
"text.c". I'll provide it at the end of this post. I found text.c in
a book called _Linux_Programming_Unleashed_ by Kurt Wall, et al. and
published by Sams Publishing.

At first I was sure that there was something terrible happening which I
could not explain. I struggled with it for several hours. Finally,
exhausted, I looked for a news group where I could post a question. I
found this news group, and here I am.

I wrote a message about the problem. I explained that the compiled
program, "text", worked correctly for me only in the TWM window manager
on my Slackware 12.0 system. I tried Kde, Fluxbox, Fvwm2, and Xfce
also, but they all showed a peculiar problem. Which was this: They
would allow a repositioning of the box shaped cursor (by clicking in
the Widget window), but they would never allow the widget window to
accept the text that I would try to type into it. In fact, except for
the cursor repositioning, I got no sign that the window had accepted
the focus.

Well, I got all the way to the end of my message and I mentioned what
page of the book the source code came from and how I compiled it. As
often happens, my carefully phrased question prompted me to discover
the answer myself. Ha! I had compiled text.c incorrectly! The book
provided a Makefile and compilation instructions.

After compiling per the book's instructions the text program worked
perfectly in Fvwm2. I have not yet tried it in the other window
managers that I mentioned, so I'll do that after I post this and let
you know if I found any trouble.

So, my mistake was one of compilation it seems.

Here is the wrong compilation:

cc text.c -o text -l X11 -l Xt -l Xaw

And here is the one that was provided by the book (and seems to be OK):

cc -o text text.c -L/usr/X11R6/lib -lX11 -lXaw

I believe these two differences may be significant:

1. I initially used "-l Xt" instead of "-L/usr/X11R6/lib"
2. I listed the libraries in a different order

So what is going on here? Does anyone out there know the how and why
of listing libraries when compiling? I don't know if the order of
listing libraries matters. I also don't know what the difference is
between "-l Xt" and "-L/usr/X11R6/lib".

Help me to understand if you can.

Thanks.

-Joe

Here is the source for text.c:

***

#include <X11/Intrinsic.h>
#include <X11/StringDefs.h>

#include <X11/Xaw/Paned.h>
#include <X11/Xaw/AsciiText.h>
#include <X11/Xaw/Command.h>

void do_display_widget_text(Widget w, XtPointer text_ptr, XtPointer unused) {
Widget text = (Widget) text_ptr;
String str;
XtVaGetValues(text,
XtNstring, &str,
NULL);
printf("Widget Text is:\n%s\n", str);
}

void do_erase_text_widget(Widget w, XtPointer text_ptr, XtPointer unused) {
Widget text = (Widget) text_ptr;
XtVaSetValues(text,
XtNstring, "",
NULL);
}

XtAppContext application_context;

void do_quit(Widget w, XtPointer unused1, XtPointer unused2) {
XtDestroyApplicationContext(application_context);
exit(0);
}

String app_resources[] = {
"*Text*editType: edit",
"*Text*autoFill: on",
"*Text*scrollVertical: whenNeeded",
"*Text*scrollHorizontal: whenNeeded",
"*erase*label: Erase the text widget",
"*display*label: Display the text from the text widget",
"*Text*preferredPaneSize: 300",
NULL,
};

int main(int argc, char **argv) {

Widget top_level, paned, text, erase, display, quit;
char *initial_text= "Try typing\n\nsome text here!\n\n";

top_level = XtAppInitialize(&application_context, "textexample", NULL, 0,
&argc, argv, app_resources,
NULL, 0);

paned = XtVaCreateManagedWidget("paned", panedWidgetClass, top_level,
NULL);

text = XtVaCreateManagedWidget("text", asciiTextWidgetClass, paned,
XtNtype, XawAsciiString,
XtNstring, initial_text,
NULL);

erase = XtVaCreateManagedWidget("erase", commandWidgetClass, paned,
NULL);

display = XtVaCreateManagedWidget("display", commandWidgetClass, paned,
NULL);

quit = XtVaCreateManagedWidget("quit", commandWidgetClass, paned,
NULL);


XtAddCallback(erase, XtNcallback, do_erase_text_widget, (XtPointer) text);
XtAddCallback(display, XtNcallback, do_display_widget_text, (XtPointer) text);
XtAddCallback(quit, XtNcallback, do_quit, (XtPointer) text);

XtRealizeWidget(top_level);
XtAppMainLoop(application_context);

return 0;
}

***

This example comes from page 602 in chapter 26.
From: Vadim Zeitlin on 10 Mar 2010 05:32
On 2010-03-07, Joseph Rosevear <joe(a)max.hopto.org> wrote:
> Hello to you in comp.soft-sys.wxwindows,
>
> I'm new to this news group and also new to X programming.

Hello,

Unfortunately I think you're in the wrong group, this one is about
wxWindows (now called wxWidgets) development, see www.wxwidgets.org, and
not about X Windows (this small "w" in the beginning changes everything).
OTOH maybe you should try using wxWidgets instead of raw X as it's much,
much simpler this way.

Regards,
VZ

--
TT-Solutions: wxWidgets consultancy and technical support
http://www.tt-solutions.com/
From: Joseph Rosevear on 11 Mar 2010 00:12
Vadim Zeitlin <vadim(a)wxwidgets.org> wrote:
> On 2010-03-07, Joseph Rosevear <joe(a)max.hopto.org> wrote:
> > Hello to you in comp.soft-sys.wxwindows,
> >
> > I'm new to this news group and also new to X programming.

> Hello,

> Unfortunately I think you're in the wrong group, this one is about
> wxWindows (now called wxWidgets) development, see www.wxwidgets.org, and
> not about X Windows (this small "w" in the beginning changes everything).
> OTOH maybe you should try using wxWidgets instead of raw X as it's much,
> much simpler this way.

> Regards,
> VZ

> --
> TT-Solutions: wxWidgets consultancy and technical support
> http://www.tt-solutions.com/

Vadim,

Yes, I see now that I'm in the wrong group. Sorry about that.

-Joe
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