>> (e) I'm using the "touchscreen as hand tool" feature, but I'd like to
>> improve it: I'd also what that it behaves like many other touch screen
>> aware programs in the way that you can "give it a kick" so that it goes
>> on scrolling for a little while. (That's much more handy when scrolling
>> over long distances.) That of course means that the finger does not
>> behave exactly like the hand tool, but rather is something separate.
>
> Not so easy right now, because xournal is not time-aware so you can't
> tell easily if a sequence of touchscreen events is a long slow scroll or
> a quick flick. Of course, input events have timestamps so this should
> not be impossible -- but that part of the code is already complicated
> enough.
>
> If you want to do this for touch gestures then I think the hand tool
> should do it too -- why not give a kick with the pen or with the mouse
> as well if those are the input devices being used to work with the hand
> tool ? The hand tool should morally behave like a touchscreen, whether
> it's being used via a touchscreen or something else.
>
> So: in the hand tool code, when starting a hand tool (look for
> "ui.cur_item_type = ITEM_HAND" in xo-callbacks.c) one should not just
> set ui.hand_refpt but also record the timestamp of the event for future
> purposes... but I'm not sure exactly how far you'd want to keep
> scrolling, and whether you'd just want to paralyze the rest of the user
> interface while we do this, or how to handle things if the user starts
> drawing while you still wanted to keep scrolling?
I already thought about those things:
- How long/far to keep scrolling: this will need some experimenting to
see what feels best; but similarly to other programs
- While it's scrolling, any mousedown within the canvas immediately
stops scrolling; then the mousedown event is processed as normally. (I
think that's what one would intuitigely expect: the pen stops the paper
from gliding. Moreover, nobody would want to draw while the paper is moving)
- For other clicks (in the menu, or choosing a different tool), I'd tend
to just let the scrolling continue while they happen, but if for some
reason, that would be complicated, one can also simply stop the scrolling.
>
> I have not seen convincing hand gestures of this sort in applications
> that allow editing rather than just viewing. Because of the interaction
bluefish (a texteditor) does this. (There are many reasons for which I
don't like bluefish, but I do like the way it deals with scrolling.)
> between scrolling in such a manner and drawing immediately after a touch
> gesture (or imagine a spurious hand touch as you're about to start
> writing with the stylus!!), I am not convinced that xournal is a good
> place to start thinking about this.
You're right; this continued scrolling should not be too sensitive, so
that one doesn't start it accidentally.
I think I'll experiment with this, and you can decide whether you like
it once I have a version I'm happy with.
Best,
Immi
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