In comp.windows.x, Christof Krueger

wrote
on Sun, 18 Jan 2004 19:13:41 +0100
:
> Hello,
>
> I'm new to X (using xlib on Linux). I create a window and want to be
> notified whenever some event happens. I knot that I have to specify the
> events of interest by using XSelectInput.
> But how can I catch the event that a user closes the window with the
> "x"-button from the window manager?
> When a user pushes the button, i get
> X connection to :1.0 broken (explicit kill or server shutdown)
> in the console where i stared my program.
> XNextEvent does not return at this point. My program is simply terminated.
>
> Thanks in advance!
>

Things get mildly interesting at this level. First, one should
use XSetWMProtocols on the window; this takes an array of Atoms.

These atoms include:

"WM_TAKE_FOCUS" -- program is expecting to handle keyboard input
from this window.
"WM_DELETE_WINDOW" -- program will want to see the close request
on this window.
"WM_SAVE_YOURSELF" -- I'm not sure exactly when this gets used,
but it probably has to do with session management; when the
session manager goes down each window is asked to save its
position and/or settings so that when the user logs in again
and asks to resume his session, the program can oblige.
At least, that's my understanding; you may want to find
the ICCCM specifications for a clearer response.

These are not pre-registered atoms; use XInternAtom() if you need to.
You need only use XInternAtom() once for each new Atom.

Once you've registered these protocols (which, BTW, is
merely a convenient abbreviation for a certain property
name on the toplevel window; I'd have to look), you will
receive ClientMessage events. Once you've registered
WM_DELETE_WINDOW, the window manager will not terminate
your Display connection -- your program gets to instead
close the window (either by unmapping it or by destroying
it), and whatever else it deems necessary. For example,
the program can pop up a dialog box asking "you forgot
to save the file: [save and close] [just close] [cancel]"
or some such.

Happy hacking. :-)

--
#191, ewill3@earthlink.net
It's still legal to go .sigless.

The Ghost In The Machine wrote:
> In comp.windows.x, Christof Krueger
>
> wrote
> on Sun, 18 Jan 2004 19:13:41 +0100
> :
>
>>Hello,
>>
>>I'm new to X (using xlib on Linux). I create a window and want to be
>>notified whenever some event happens. I knot that I have to specify the
>>events of interest by using XSelectInput.
>>But how can I catch the event that a user closes the window with the
>>"x"-button from the window manager?
>>When a user pushes the button, i get
>>X connection to :1.0 broken (explicit kill or server shutdown)
>>in the console where i stared my program.
>>XNextEvent does not return at this point. My program is simply terminated.
>>
>>Thanks in advance!
>>
>
>
> Things get mildly interesting at this level. First, one should
> use XSetWMProtocols on the window; this takes an array of Atoms.
>
> These atoms include:
>
> "WM_TAKE_FOCUS" -- program is expecting to handle keyboard input
> from this window.
> "WM_DELETE_WINDOW" -- program will want to see the close request
> on this window.
> "WM_SAVE_YOURSELF" -- I'm not sure exactly when this gets used,
> but it probably has to do with session management; when the
> session manager goes down each window is asked to save its
> position and/or settings so that when the user logs in again
> and asks to resume his session, the program can oblige.
> At least, that's my understanding; you may want to find
> the ICCCM specifications for a clearer response.
>
> These are not pre-registered atoms; use XInternAtom() if you need to.
> You need only use XInternAtom() once for each new Atom.
>
> Once you've registered these protocols (which, BTW, is
> merely a convenient abbreviation for a certain property
> name on the toplevel window; I'd have to look), you will
> receive ClientMessage events. Once you've registered
> WM_DELETE_WINDOW, the window manager will not terminate
> your Display connection -- your program gets to instead
> close the window (either by unmapping it or by destroying
> it), and whatever else it deems necessary. For example,
> the program can pop up a dialog box asking "you forgot
> to save the file: [save and close] [just close] [cancel]"
> or some such.
>
> Happy hacking. :-)
>

Thank you very much!
I googled a lot and even came across WM_DELETE_WINDOW but didn't read
further because it looked like MS Windows API Messages to me. Now I
understand that WM stands for WindowManager. =)

Do you know a good reference site about such details? I'm using
tronche.com as reference at the moment. It is good to look up functions,
but it is difficult to learn from it.

--
Regards,
Christof Krueger

Remove "donotspam" if you want to email me.

In comp.windows.x, Christof Krueger

wrote
on Mon, 19 Jan 2004 14:11:47 +0100
:
> The Ghost In The Machine wrote:
>> In comp.windows.x, Christof Krueger
>>
>> wrote
>> on Sun, 18 Jan 2004 19:13:41 +0100
>> :
>>
>>>Hello,
>>>
>>>I'm new to X (using xlib on Linux). I create a window and want to be
>>>notified whenever some event happens. I knot that I have to specify the
>>>events of interest by using XSelectInput.
>>>But how can I catch the event that a user closes the window with the
>>>"x"-button from the window manager?
>>>When a user pushes the button, i get
>>>X connection to :1.0 broken (explicit kill or server shutdown)
>>>in the console where i stared my program.
>>>XNextEvent does not return at this point. My program is simply terminated.
>>>
>>>Thanks in advance!
>>>
>>
>>
>> Things get mildly interesting at this level. First, one should
>> use XSetWMProtocols on the window; this takes an array of Atoms.
>>
>> These atoms include:
>>
>> "WM_TAKE_FOCUS" -- program is expecting to handle keyboard input
>> from this window.
>> "WM_DELETE_WINDOW" -- program will want to see the close request
>> on this window.
>> "WM_SAVE_YOURSELF" -- I'm not sure exactly when this gets used,
>> but it probably has to do with session management; when the
>> session manager goes down each window is asked to save its
>> position and/or settings so that when the user logs in again
>> and asks to resume his session, the program can oblige.
>> At least, that's my understanding; you may want to find
>> the ICCCM specifications for a clearer response.
>>
>> These are not pre-registered atoms; use XInternAtom() if you need to.
>> You need only use XInternAtom() once for each new Atom.
>>
>> Once you've registered these protocols (which, BTW, is
>> merely a convenient abbreviation for a certain property
>> name on the toplevel window; I'd have to look), you will
>> receive ClientMessage events. Once you've registered
>> WM_DELETE_WINDOW, the window manager will not terminate
>> your Display connection -- your program gets to instead
>> close the window (either by unmapping it or by destroying
>> it), and whatever else it deems necessary. For example,
>> the program can pop up a dialog box asking "you forgot
>> to save the file: [save and close] [just close] [cancel]"
>> or some such.
>>
>> Happy hacking. :-)
>>
>
> Thank you very much!
> I googled a lot and even came across WM_DELETE_WINDOW but didn't read
> further because it looked like MS Windows API Messages to me. Now I
> understand that WM stands for WindowManager. =)
>
> Do you know a good reference site about such details? I'm using
> tronche.com as reference at the moment. It is good to look up functions,
> but it is difficult to learn from it.
>

Not sure how good it is but there's an ICCCM manual on that
very site:

http://tronche.com/gui/x/icccm/

which a Google search on "ICCCM" turned up. Among many other things,
it mentions the "WM_PROTOCOLS" property, which is the property I
referred to earlier. It appears WM_SAVE_YOURSELF has been deprecated,
so don't worry about it. Also, I'm in error (interesting!); the
unmapping of the window is not an option although withdrawing it
(XWithdrawWindow) is.

Or you can try http://www.oreilly.com , although I for one can't seem
to find X there and bumbled around to

http://www.oreilly.com/catalog/prdindex.html

The books for X are titled "Volume 0" through "Volume 6B"; the examples
are apparently freely downloadable although it's not clear to me how
much sense they'll make without the book. :-) Please bear in mind
there are license restrictions.

--
#191, ewill3@earthlink.net
It's still legal to go .sigless.

Hi!

I'm new to X programming too. A few days ago I found great source of
specifiactions and manuals at
http://www.xfree86.org/snapshot/specindex.html.

The specs are avaiable in PDF and HTML. Altough it seems that HTML
versions have been generated from the PDF so every HTML spec is one
very long page. I prefer to use the original PDF versions. For ad-hoc
search you can (when you know exactly what yoy search) use man pages
(http://www.xfree86.org/current/manindex3.html).

The most important stuff is:
(1) Core X Protocol Library API
This should cover what the manual at tronche.com does and probably
more. The tronche doesn't cover some things at all (i18n) and it's a
bit old too.

(2) ICCCM (Inter-Client Communcations Conventions Manual)
This specifies a set of conventions how the X clients would
communicate (communication between regular clients as well as regular
client to window manager communication). Here you can find answers to
your original question.

Also I found some useful texts at
http://freedesktop.org/Standards/Home.
For example if you would like support some drag-and-drop features, see
http://freedesktop.org/Standards/XDND. It's de facto (not official)
standard (Gtk+ and Qt toolkits use that for example).

I hope it helps you.
Mity