address@hidden: Re: [Xpert]Default fonts for menus, dialogues, etc]

[Richard Stallman]

This gives information that ought to tell us how to find the actual
default foreground and background colors, first for the Athena widgets
and then for Lesstif/Motif.  The first example starts by creating a
widget, but I suspect we can use any existing one.

Can someone use this to initialize the `menu' face so that we can
eliminate the fallback resources?

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Subject: Re: [Xpert]Default fonts for menus, dialogues, etc
Date: Wed, 05 Dec 2001 15:44:39 -0200 (BRDT)
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Quoting Richard Stallman <address@hidden>:

  Hi,

>       Sorry, I didn't make myself clear. In xc/lib/Xt/Core.c, one field
> of the
>     default resources of the core widget is:
>       {XtNbackground, XtCBackground, XtRPixel,sizeof(Pixel),
>            XtOffsetOf(CoreRec,core.background_pixel),
>            XtRString, (XtPointer)"XtDefaultBackground"},
> 
> Unfortunately, I have no idea what this really means.  I don't really
> know Xt internals at all.  What I can tell is that you are using the
> term "resources" in a way I don't understand.

  I was talking about resources in it's internal representation and the
data associated for translating it from one type to another, i.e. translating
from the string representation to the binary representation.

> Could you possibly show me what a user program should do to find the
> value of XtDefaultBackground?  Is XtDefaultBackground a C function?

  The simplest program I can think of is this:
- --%<--
#include <X11/Intrinsic.h>
#include <X11/StringDefs.h>

int
main(int argc, char *argv[])
{
    XtAppContext appcon;
    Widget widget;
    XrmValue from, to;
    Pixel fg, bg;
    char *background = XtDefaultBackground;
    char *foreground = XtDefaultForeground;

    /* make sure Xt internals are initialized and get a valid widget pointer */
    widget = XtAppInitialize(&appcon, "Test", NULL, 0,
                             &argc, argv, NULL, NULL, 0);

    from.size = strlen(background);
    from.addr = background;
    to.size = sizeof(Pixel);
    to.addr = (XtPointer)&bg;
    XtConvertAndStore(widget, XtRString, &from, XtRPixel, &to);
    printf("%s has the pixel value 0x%08x\n", background, bg);

    from.size = strlen(foreground);
    from.addr = foreground;
    to.size = sizeof(Pixel);
    to.addr = (XtPointer)&fg;
    XtConvertAndStore(widget, XtRString, &from, XtRPixel, &to);
    printf("%s has the pixel value 0x%08x\n", foreground, fg);

    /* read from widget */
    XtVaGetValues(widget, XtNbackground, &bg, XtNforeground, &fg, NULL);
    printf("background: 0x%08x\nforeground: 0x%08x\n", bg, fg);

    return (0);
}
- --%<--
compile as: gcc test.c -I/usr/X11R6/include -L/usr/X11R6/lib -lX11 -lXt

> If so, could you tell me what arguments it wants?
> 
>       See lib/Xm/Visual.c for the function _XmBackgroundColorDefault.
> 
> I am not sure what directory to look for that file name in.  Is that a
> Motif source file?  I don't have a copy of Motif, and I would hesitate
> to get one since it isn't free software.

  No, it is in the lesstif sources :-)

> But if calling this function is the right thing for Emacs to do, in
> the Motif case, if you could just show me what arguments to give it
> then I would know everything I need.

  Probably all you need to do then is some code like this, after the widget
is created:

  Pixel defbackground, defforeground;

  XtVaGetValues(widget, XtNbackground, &defbackground,
                XtNforeground, &defforeground, NULL);

  The sample code above also does this.

Paulo
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