[maemo-developers] hildon im to X key proxy

[From: Eero Tamminen]

Hi,

ext Austin Che wrote:
>     I've been trying to get something like the following to work:
>     
>     - I want to be able to press power, menu or something like that to
>     bring up the on-screen keyboard
>     - Then any keys I press should be sent as normal X key events
>     (i.e. same as if I pressed them on a keyboard)
>     - If I press a hardware key like the menu button, the next key
>     pressed on the vkb is sent as a ctrl character instead

You could use something like matchbox-nest:
	http://packages.debian.org/etch/matchbox-keyboard


>     Here's my current implementation:
>     
>     - I create a hidden window. I create a new hildon IM context and
>     set the hidden window to be the client.
>     - Keys pressed on the vkb are caught via the "commit" signal and
>     converted to a unicode character.
>     - I use gdk_unicode_to_keyval to convert it to a GDK keyval which
>     I believe has a 1-to-1 mapping to X keysyms

Unicode covers a much larger range than X keysyms.


>     - XChangeKeyboardMapping is used to set an arbitrary unused
>     keycode to map to the desired keysym
>     - I then use XTest to generate a fake key of the given keycode
>     
>     It mostly works but there are some issues:
> 
>     - I cannot make a completely hidden window. The best I can do is a
>     1x1 pixel window that shows up as a white dot in the top left
>     corner. Making it zero size, moving it off screen, or trying to
>     make it transparent don't seem to work.
> 
>     - I set the hidden window to not accept-focus. This is so that
>     when I use XTestFakeKeyEvent, the key is sent to the current top
>     application. However, this also means the hidden window cannot
>     directly get the hardware key presses. I can get it in other ways
>     such as directly from the device file, but it seems like there
>     should be a better solution. If I give the hidden proxy window the
>     focus, I can't figure out how to lose the focus before sending the
>     fake key.
>     
>     - When using it with something like the X terminal which normally
>     pops up the vkb itself, it works for a couple characters (not
>     repeatable how many characters) and then my proxy stops receiving
>     keyboard events. I believe it's because the app realizes it has
>     the focus and it resets the client window for the vkb to be
>     itself. This problem doesn't exist when I use it with something
>     that doesn't normally pop up the vkb (e.g. running emacs over X
>     remotely). If there was some way to determine when the client
>     window for the vkb has changed, that would probably be good enough
>     to reset it back to the proxy window.
> 
>     - Normally, when the vkb pops up, the window underneath is
>     automatically resized. But when doing the above, the top window is
>     not resized so it ends up that the keyboard covers the bottom of
>     the window. How can I force the window underneath to resize?

The application tells the window manager for which window the keyboard
is opened with an X property I think.


>     - Is there some way to tell when the vkb has been hidden by the
>       user?
>     
>     Any hints appreciated.


	- Eero