Fix slurp -o "selection cancelled" with touch inputs

[stacyharper]

fixes: #140

[emersion]

Hm it seems we call this function on pointer release and on touch down… Shouldn't we call it on touch up instead?

[stacyharper]

I tried to move this to touch_handle_up and it doesn't works as intended.

[stacyharper]

We could move the call to seat_update_selection to touch_handle_up, and conditioned it to be run if there is still no selection at this point. It allow to select rects on simple touches, while still allowing manual box selections.

But the problem is the case of slurp -o -r. To handle that, we also have to add this function to touch_handle_down, before handle_selection_start. Because in this situation, handle_selection_start will finish the loop. Then, the seat_update_selection call from touch_handle_up becomes redundant, so we can remove it.

[emersion]

Sorry, but I still don't understand what's peculiar about touch input that makes it different from pointer input here.

[stacyharper]

I don't get it. We update the selectioned box on touch down because this is the only moment we can, and have to do so.

[emersion]

The pointer codepath does not call seat_update_selection() when a button is pressed. Why does touch down need to call it?

[stacyharper]

Because we know where the pointer is before the user press any button. We don't know where the user finger is before it actually touch the screen.

[stacyharper]

Gentle bump. Could this be reviewed? I continue to think the fix is good, even if it looks wrong with a first glance.