Re: [Qemu-devel] [PATCH] touchscreen screen coordinates

[andrzej zaborowski]

Hi,

On 19/06/07, address@hidden <address@hidden> wrote:
> Attached is a simple patch (for 0.9.0 and current cvs), that allows:
>
> -usbdevice touchscreen
>
> which behaves the same as touchpad, except the coordinates are screen
> coordinates instead of scaled 32768 coordinates.
>
> This makes qemu compatible with tslib, often used by xserver-kdrive.
> tslib does not scale usb input to screen. tslib assumes input is screen
> coordinates.

To be precise, tslib assumes that you calibrate the touchscreen on
first boot, or have an /etc/pointercal file provided.  So this is
another way to have it report the right coordinates.

> (Well tslib requires a small patch to allow button events to work like
> pressure events).
>
> Perhaps an additional or alternative change could separate usb
> touchscreen support from tablet, such that ABS_PRESSURE events are
> generated instead of left button.

This is why -usbdevice wacom-tablet was added.  It lets you use
unmodified tslib because the linux driver for the tablet reports also
touch pressure.  It works for OpenEmbedded builds for i386 and arm
(although for arm there is also the ADS7846 touchscreen).

Adding a HID touchscreen may be another possibility.

Regards,
Andrzej