Re: [Qemu-devel] [PATCH] usb-hid: Fix 0/0 position for Windows in tablet mode

[Jan Kiszka <jan.kiszka@web.de>]

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On 2011-06-25 15:10, Andreas Färber wrote:
> Am 25.06.2011 um 14:55 schrieb Jan Kiszka:
> 
>> On 2011-06-25 14:37, Andreas Färber wrote:
>>> Am 24.06.2011 um 16:27 schrieb Jan Kiszka:
>>>
>>>> For unknown reasons, Windows drivers (tested with XP and Win7) ignore
>>>> usb-tablet events that move the pointer to 0/0. So always set bit 0 of
>>>> the coordinates.
>>>>
>>>> Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
>>>> ---
>>>> hw/usb-hid.c |    6 ++++--
>>>> 1 files changed, 4 insertions(+), 2 deletions(-)
>>>>
>>>> diff --git a/hw/usb-hid.c b/hw/usb-hid.c
>>>> index d711b5c..2b9a451 100644
>>>> --- a/hw/usb-hid.c
>>>> +++ b/hw/usb-hid.c
>>>> @@ -457,8 +457,10 @@ static void
>>>> usb_pointer_event_combine(USBPointerEvent *e, int xyrel,
>>>>        e->xdx += x1;
>>>>        e->ydy += y1;
>>>>    } else {
>>>> -        e->xdx = x1;
>>>> -        e->ydy = y1;
>>>> +        /* Windows drivers do not like the 0/0 position and ignore
>>>> such
>>>> +         * events. */
>>>> +        e->xdx = x1 | 1;
>>>> +        e->ydy = y1 | 1;
>>>
>>> Doesn't this change mean we can't access any other even pixel either?
>>
>> Only on 32767x32767 screens (that's the resolution of the tablet).
> 
> Well, if it's just a fix for 0/0 I would've expected something like:
> 
> e->xdx = x1 ? x1 : 1;
> e->ydy = y1 ? y1 : 1;

Works as well, my version is a little bit simpler. But I don't mind,
will post whatever is preferred to fix this.

Jan


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