Touch events

[Chase Douglas]

On 02/23/2012 12:22 PM, Bill Spitzak wrote:
> Chase Douglas wrote:
>
>> The client won't see the third finger if it touches outside its window.
>> In the wayland case, only the WM has all the info needed to determine if
>> a touch is part of a global gesture. The WM needs to make the decision,
>> not the client.
>
> I'm pretty certain all touch events *MUST* go to the same surface until
> all touches are released. Otherwise it will be quite impossible to do
> gestures reliably, like the user could not do them to objects near the
> edge of a window.

No? I'm not sure what to say other than this is plainly incorrect. For a 
touchscreen device, the user may be interacting with two separate 
applications at the same time. Imagine you have your web browser open on 
the left side of the screen, and you have your spreadsheet open on the 
right side. You then want to scroll both side by side as you compare 
numbers. To do this, you need to send touch events to each client 
separately.

I'm fairly certain that no window system in major use behaves as you 
suggest.

>>> If the clients can look at things first, this would allow the compositor
>>> to do things like "one finger can be used to change desktops if the
>>> underlying program does not use it".
>>
>> That would be bad UI design because then global gestures would fire only
>> sometimes. Further, it would break global gestures if touches occur over
>> a broken application.
>
> I consider it bad design that global actions are "complex" (like needing
> 3 fingers) or global shortcuts require lots of shift keys held down,
> just to avoid collisions with applications.

My belief is that it is considered, universally (meaning >95% of 
people), that global gestures should behave consistently across 
applications, and should not be inhibited by broken applications.

I also believe that 3 or more finger global gestures are not bad design, 
especially since the iPad uses them. Maybe individuals like yourself 
don't like them, but very many do.

I'm not trying to start an argument about what is the best design of 
global gestures. However, I think it is a requirement that the window 
system allows for consistent global gesture behavior, and that three or 
more touch gestures are valid for global gestures.

> I also think you are making up "user confusion" that does not exist in
> the real world to make an excuse for this. Users will find it pretty
> obvious if the same action that scrolls a document also scrolls the
> entire screen if you don't touch a document, IMHO.

How would it not be confusing if you have a global "alt-tab" gesture 
work when performed over your spreadsheet but not your browser?

>> I think we can look at other OSes as case studies. iOS and OS X employ
>> effective global gestures imo, and they take precedence over the
>> application receiving touch or gesture events.
>
> I think it is pretty clear that "what other OS's do" is not always what
> Wayland wants to do. Most of them copied ideas from X.

That's why I said we should look at them as case studies...

-- Chase