Gtk window object
lazarus / 8-Other

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Spike · 2006-08-03 15:43

In porting my (windows) project to gtk2, I need a little bit of focus-
magic and for that I'm using xlib. The only problem is that right now,
in order to obtain the window id of one of my forms, I'm using a
really unreliable "XGetInputFocus" while praying that the returned
window is the one I'm looking for.
So I've tried to take a peek into the gtk2 interface sources, but that
code is way too "spagetti" for me to handle right now. All that I know
is that the code that's supposed to switch focus has a "//TO DO:
Implement me" comment within. I went on and looked at the gtk2 docs
and found a really nifty method that puts my window on top, gives it
focus and takes care of any unwanted side effects, but that requires a
GtkWindow object reference as a parameter. So I was back at square
one, trying to figure out by myself where is that handle stored, but
like I said, the pure spagettiness (that's most likely not a word) of
the LCL pushed me away.
Now this post is getting longer than I wanted, so I'm just gonna cut
this short:
Who do I have to kill to get that object reference, or even better, a
window ID to use the XLib functions (so that I don't have to do this
again should I want qt compatibility later on)

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felipemdc · 2006-08-03 17:03

Take a look here: http://wiki.lazarus.freepascal.org/index.php/Accessi
ng_the_Interfaces_directly

under gtk a Handle is often a PGtkWidget

You need to use the Handle property of your window (or other control)
to get access to a GtkWindow. Then you can use that value to access
Gtk functions directly. Some Gtk functions will give you access to a
X11 Handle.

I don´t remember them from memory, but just look at how TTrayIcon
component was implemented. It´s located at lazarus/components/trayicon
on your local Lazarus install.

Specifically take a look at the Gtk2 file from trayicon.

> so that I don't have to do this again should I want qt compatibility
later on

You will have to put platform dependent code to get support for qt and
gtk. Even if it´s just 2 lines, because LCL gives access to a Handle
of the widgetset it´s using, not a Handle to the Windowing system
being utilized.

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Spike · 2006-08-03 17:20

Thanks for the post.
I knew that under windows, the Handle property is a hwnd, but I wasn't
sure on what it represented on other widgetsets.

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Marc · 2006-08-09 09:00

Please be aware that this might change in the future.