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Date: Mon, 17 Jun 2013 09:16:45 +0200
From: Gerd Hoffmann <kraxel@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH RFC 0/8] monitor: Fix mouse_button and
 improve mouse_move commands
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To: =?UTF-8?B?QW5kcmVhcyBGw6RyYmVy?= <afaerber@suse.de>
Cc: "Bernhard M. Wiedemann" <bwiedemann@suse.de>, xen-devel <xen-devel@lists.xensource.com>, Stephan Kulow <coolo@suse.de>, Brad Hards <bradh@frogmouth.net>, Peter Maydell <peter.maydell@linaro.org>, Stefano Stabellini <stefano.stabellini@eu.citrix.com>, Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>, qemu-devel@nongnu.org, Luiz Capitulino <lcapitulino@redhat.com>, Blue Swirl <blauwirbel@gmail.com>, Alexander Graf <agraf@suse.de>, qemu-ppc <qemu-ppc@nongnu.org>, Paolo Bonzini <pbonzini@redhat.com>, Ludwig Nussel <lnussel@suse.de>

  Hi,

> My solution is to obtain position and buttons state from where the VMState is:
> I clean up the mouse event handler registration code a bit and extend it:
> * one mandatory callback to obtain mouse button state and
> * one optional callback to obtain absolute position state from backends.

Hmm, querying state from the mouse drivers just to be able to pass it
back in is a bit backwards.

I'd rather go fix the event reporting interface.  Instead of having
*one* callback with *all* parameters I think we should have a callback
per parameter, or maybe better a parameter type enum.  i.e. instead of:

  mouse_event(x, y, z, button_state)

We'll have

  mouse_event(type, value)

Then we'll report moves this way:

  mouse_event(REL_X, 23);     // or ABS_X for the tablet.
  mouse_event(REL_Y, 42);
  mouse_event(SYNC, 0);       // <<= means "done, flush events to guest"

And klicks this way:

  mouse_event(DOWN, BTN_LEFT);
  mouse_event(SYNC);

  mouse_event(UP, BTN_LEFT);
  mouse_event(SYNC);

The linux input layer works in a simliar way.

cheers,
  Gerd