[Haskell-cafe] ANNOUNCE: usb-0.3

stefan kersten sk at k-hornz.de
Wed Dec 9 11:54:05 EST 2009

hi roel,

On 09.12.09 16:50, Roel van Dijk wrote:
> On Wed, Dec 9, 2009 at 4:20 PM, stefan kersten <sk at k-hornz.de> wrote:
>> looks great, thanks! do you happen to have some example code for working with
>> HID devices (mice, keyboards, etc.)?
> The usb package does not support the various device classes directly.
> You won't find a function like "isKeyPressed ∷ Device → KeyCode → IO
> Bool". But you could write it based solely on functions from the usb
> package. Enumerate the devices connected to your system, find your HID
> device, open a handle (or enter a safe region), choose an interface
> and an alternative and finally send some sort of control request
> encoded in a ByteString. The actual bytes you need to send in order to
> discover if some key on your USB keyboard is pressed is defined
> somewhere in the USB HID device class specification.

ok, thanks. i just thought you might have something ready to use ;)

> If you really need that kind of functionality then you could create a
> package "usb-hid" that offers an abstraction over the HID device
> class. But if you just want to know if some key is pressed then a much
> simpler solution would be to use a library like SDL or GLUT.

i'm interested in "headless" appliances, where no window system is actually
running. on linux i could use the input device layer, but it would be nice to
have something more portable ...


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