[sdk] Buttons and other widgets are too small for comfortable touch usage

[Daniel van Vugt]

[Updated description]

On Ubuntu phones, buttons and other widgets are too small for comfortable touch usage.

This is mostly about buttons like those seen in the shutdown dialog. They feel too small (they are in fact 5.5mm high) to be able to reliably hit with a finger, and that's on arale which has a large screen.

But our GUI elements vary in size a lot and we got it right in the many menus/list views. There, each row is a nice comfortable height (10mm).

Compare to Android 5.1.1 on a hammerhead where buttons/list items are 12-15mm high, the larger size is more comfortable and faster to use.

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Update:

The shut-down dialogue will follow new rules we are defining for button size and spacing which will appear with updated SDK UI items.

The GUI elements should all be touch friendly and consistent in size.

Kanban card: https://canonical.leankit.com/Boards/View/109386535/115024098

[Andrea Bernabei (faenil)]

The UX spec documents states that the touch area of components must be at least 4x4gu, unless configured otherwise by the app developer.

I attached an MR by zsombi that implements that for AbstractButton-based components.

[Daniel van Vugt (vanvugt)]

Can we calculate in millimetres what 4x4gu is? Because we're talking about physical human fingers here, so the threshold for usability is a physical length.

[Andrea Bernabei (faenil)]

The ideal would be 7-8mm if I rememeber correctly. But we don't have a *reliable* way to detect that in our platform, as far as I know. Our universal unit is the GU, so that's what we're basing on.

If you know of an API that our platform already offers, please comment on the MR, having the physical size would be awesome.

[Daniel van Vugt (vanvugt)]

In the bug description I pointed out 10-15mm is actually much more comfortable. But this is something Ubuntu UX can figure out themselves.

The Mir client API provides the physical screen dimensions in millimetres, or if it's more convenient also provides per-surface DPI events.

[Andrea Bernabei (faenil)]

The size I reported comes from the UX spec.
The UX team researched that before writing the spec

Just a random link on the subject: http://www.lukew.com/ff/entry.asp?1085

[Andrea Bernabei (faenil)]

About the Mir API, I asked greyback before replying to your previous comment, and he confirmed we don't have a reliable way of representing physical sized, for example on a projector the size will be 0x0.

One of the reasons we have the GU is to represent "more or less" the same physical size everywhere, so I think we don't have any other choice here...