Handling Input from Touchscreens

I wasn't going to write this (I didn't even consider this) when started this. The target environment for FatdogArm is desktop, not tablet. But I chanced to get my hands on an A10 tablet which worked nicely with what I've built so far, so it was a waste not trying to exploit what it can do, and in this case, its touch input.

To get touchscreen input to work, there are a few components which needs to be available and work together.

  1. Kernel driver for the touch input hardware.

  2. The Xorg input driver for touchscreen.
    Note: Using standard mouse modules will not work, as touch input hardware usually provides its input in absolute coordinates (instead of relative coordinates like mice).

  3. Toolkit which supports touch gestures (e.g. GTK3? QT5?)

  4. A virtual keyboard.

For the A10 tablet that I have, its input is supported by ft5x_ts module, so that part is easily sorted (other tablets may not be so lucky - some use touchscreens whose drivers are unavailable).

The Xorg input driver module is kindly donated by Pengutronix, here: http://www.pengutronix.com/software/xf86-input-tslib/index_en.html . This Xorg modules requires tslib to build; and it provides mouse-like input. As far as I know it is not multi-touch capable.

Next, one needs a touch-aware toolkit so that the applications can use the (by now) familiar idioms like tap-drag to scroll, pinch in/out to zoom, etc. Unfortunately the toolkit I'm using is GTK2 and GTK2 isn't touch-aware, so all interactions needs to be done using mouse idioms (scrollbars, etc). This is difficult, especially on smaller tablets (mine has 7 inch screen). Sure, one can enlarge the scrollbars but then precious screen space is wasted.

Lastly, one needs a virtual keyboard (otherwise, how do you do data entry?). Here, one can use xvkbd or matchbox-keyboard, among others.

I haven't tested GTK3 or any other touch-aware toolkits that is designed with touchscreens in mind, so I can't vouch for their effectiveness. But for the setup I outlined above, although it works, it is painful to use.

Thus I am still in the opinion that the best way to do real work on tablets is still to attach a physical keyboard and mouse (a large enough monitor is a bonus). Touch is fun for browsing and consuming content, but rather clumsy for "real work".