[maemo-developers] Moving windows in Maemo

[From: Kalle Vahlman]

2007/4/8, Sean Luke <sean at cs.gmu.edu>:
> Anyway, I whipped up the following little program below as a test and
> low and behold I can get the window to drag around BUT it creates all
> sorts of artifacts: screen tearing, a bizarre window flashing in the
> top-left corner, and slow updates.  The window moves very slowly
> too.  Not what I would have expected for a 300MHz machine.

Attached is a revised version of the test app, that doesn't show the
bug at least (changes commented below).

Few notes on dragging:

 - The tearing is due to the poor screen update rate (basically a hw limitation)
 - I'm under the impression that there is some (heavy?) filtering
going on wrt touchscreen input (to check the pressure data and so on),
and also physical limits of the touchscreen I guess (it's really easy
to make it think you lifted the stylys for example). Both of these
have an impact on how well the dragging will work.

> import gtk
>
> # We create a Dialog because maemo has hard-locked gtk.Window to be
> the full
> # size of the screen, and I've found now way to counteract that.

g = gtk.Window(gtk.WINDOW_POPUP)

works fine.

>  We
> then
> # delete the separator and make the window bright blue.
> g = gtk.Dialog()
> g.set_has_separator(False)
> g.set_decorated(False)
> g.modify_bg(gtk.STATE_NORMAL, gtk.gdk.Color(0,0,65535))
> g.resize(100,100)
> g.move(300,300)
>
> # We add a button to the Dialog and try to move after the Button has
> # been pushed because if you set Dialog's mask to include
> BUTTON_PRESSED,
> # no BUTTON_PRESSED event actually gets through -- instead,
> MOTION_NOTIFY
> # starts coming in incorrectly.  Looks like another bug.  So we have to
> # use a Button to grab the BUTTON_PRESSED events...
> b = gtk.Button()
> g.vbox.add(b)

I don't know what you tried here with the event mask, but

g.add_events(gtk.gdk.BUTTON_PRESS_MASK)

works just fine here (maybe it's the dialog that didn't work with this?)

-- 
Kalle Vahlman, zuh at iki.fi
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