multitouch on N900
 

Hello,

as you may know, it is possible to code a functionality similar to multitouch on a resistive screen.

I will be soon looking for a topic for a small project, so I was wondering, if you think that there is really some use for zoom in/out and rotate gesture that use two fingers? It would work similarly as on iPhone (only one finger needs to stay in place and only would move).

Would you use it on N900? Do you think it is worth spending some time on it (besides obvious fun of doing it :) )?

Thanks for your opinions.

Re: multitouch on N900
 

[source-needed] ;)
Seriously, any url about it would be an interesting read.

Re: multitouch on N900
 

install liqbase... (the old one)

Re: multitouch on N900
 

I am thinking that it would be mostly useful for marketing/fanboy argumentation. Much like the whole "resistive screen, what is this, 1999?" thing.

However, I don't think the zoom circle solution on the N900 is optimal because it drags the page around at first. A pinch or dedicated space like on the HTCs is more accurate. I am sure that some people will like an alternative to the zoom circle. So a good solution on this may just become popular.

Re: multitouch on N900
 

I may look for it, but in principle on the resistive screens the point is the average between two points of contact:

you put one finger in X, you save the position
you put second finger in Y, for the device the point of contact will move rapidly to (Y-X)/2
by moving your second finger you change the second position relatively to the first one

I hope you understand what I mean :) If not, I will try to search for any video demo, as I know it exists. You can always try this on your resistive touch device (if you have any) in you drawing program.

Re: multitouch on N900
 

I believe a similar effect can be seen in a tabletPC / wacom tablet (if you have two pointing devices) and it's behaviour sounds sort of like how the touchpad acts too. Although a touchpad is relative positioning.

Re: multitouch on N900
 

But how does the hardware or software know that there are two fingers involved, rather than just one finger in the average point between the two fingers? In other words, how does it know to do a zoom rather than a drag?

Re: multitouch on N900
 

From how it's working, it wouldn't, really. It's going to use a heuristic approach by looking at the speed of movement on the touch, which could well be incorrect.. but I'd think it would likely work fairly well in practice if well tuned.

Re: multitouch on N900
 

How the touchpad reacts is mostly because of drivers/software. Linux drivers for synaptics touchpads can do multitouch on most of the touchpads.

Re: multitouch on N900
 

Yes, that's where the fun starts :)

I believe, it should work quite well, a nice little trick...

Re: multitouch on N900
 

For multi touch you will need multi point support. X did not have multi point support for a long time, although it was in development for a long time, called MPX.

Since summer 2009 MPX is included in X Server 1.7.x. I don't know if this requires additional porting to ARMEL or Maemo and if so how straightforward this porting will be. Multi touch is also not the same as multi touch, but multi point is quite complex to implement, and that part is now ready.

However, rest assured the X Server shipped with Maemo 5 does not support MPX.

See also http://talk.maemo.org/showthread.php?t=33176 you can see some demos here as well although they use a mouse cursor; not multi touch.

Re: multitouch on N900
 

I've tried this with both my tablet PC (Paint on my OQO with a Wacom digitizer running Win7) and N810 (Xournal in drawing mode). Both screens demonstrate two recognitions.

If both pens are moved close to (in the Wacom's case) or on to the screen in approximately the same time, the software averages the two locations and puts the cursor there. If one is lifted the cursor immediately shifts to the remaining position.

If the pens are sensed one after the other, the cursor begins at the first and moves to the second. For touch screens, this is the essence of the vectoring problem in Windows handwriting recognition.

You would have to have the software define the minimum separation of registered points and the speed between registrations and their associated points to attempt to define multiple touches versus one big touch or a rapid movement of a single touch. It would also have to group all registered points into sets of touches to handle fingers rather than pens.

It wouldn't be trivial to program this nor would it be trivial for a system to run it and respond in real time. I suspect that while it could theoretically be done, it is more of a university research project than a usable system enhancement.

Re: multitouch on N900
 

Fine, but I think you missed the point a bit. He's talking about emulating multi-touch by checking for the position of a single touch moving at a rapid speed, if I understand correctly.

Re: multitouch on N900
 

@allnameswereout
Thanks for the post, it is always good to get the terminology straight :)
However, I'm not pointing into real multi-point, as the hardware (resistive screen) does not support this.

@DaveP1
I'm playing with Sketch on my N810 at the moment:
you put one finger, then you put another. now you move your second finger.
I believe it should be totally doable to recognize this effect with software.

I appreciate your technical suggestions.
What are your thoughts about usability of this pseudo multi-point (zoom in/out, rotate) in Maemo, provided it works fairly well?

Re: multitouch on N900
 

Hi guys

Felt I had to register and join the talks while I wait for my N900, along with the rest of you ;)

A brilliant guy, name Jamie Fuller has apparently made a proof-of-concept rythme game for the Nokia 5800 which (as far as i know) also has a resistive screen.
http://www.youtube.com/watch?v=XndW7YlvYjU

Re: multitouch on N900
 

I think, that this is not a good solution, because I believe, that it would not work very good.
But did you remember the 1 1/2 touch to zoom from the picsel viewer from palmos?
tap - lift - tap and hold - stroke down to zoom in, stroke up to zoom out.

Re: multitouch on N900
 

Yes, this is exactly what I have in mind (the technical side I mean). This is not a real multi touch/point, if he was pressing screen in one point exactly in the middle, he would have the same effect (both buttons would lit).

Incorporating moves would be a bit more difficult, but still possible (IMHO)

Re: multitouch on N900
 

Hi, Welcome to the forum :)

Re: multitouch on N900
 

Ah yes, didn't realize.

We call that 'gestures'. One application using them for long long time is Opera. Albeit mouse gestures.

One side effect of this emulation may be the kernel driver must then check very often for the input which will use considerably more battery juice. Although the display driver won't have to show that it checks more often; only touchscreen/input part needs to.

Re: multitouch on N900
 

I would suggest that this is a dead end. I just don't see it as reliable enough to be usable. It is much more likely to be frustrating. OTOH, I think that gesture recognition could be used. This is, essentially, an enhanced version of swipes. Take a look at StrokeIt. Who knows, it might even be portable to Maemo.

http://www.tcbmi.com/strokeit/

Re: multitouch on N900
 

Well, we could store the timestamp of the tap and check what is the difference between this tap and the previous one (including some distance threshold?)

If the difference is very small (milliseconds?) it means that the change of the tap position was made due to second finger tapped, not just finger moved (again, distance threshold)

[edit] Yes, I'm not fighting for this idea, just curious about opinions :)

Re: multitouch on N900
 

Maybe I'm not understanding it thoroughly but my take is that touchscreen driver would not be aware of starting point so this difference must be constantly calculated based on the previous values. This must be polled the whole time when screen is active (or when off e.g. when used as 'remote' for other device).

A solution to problem may be to allow to enable/disable gestures, and an application should tell driver to 'enable support for gestures' only when the application 1) supports gestures requiring this feature 2) has this gestures support enabled. This is discussed via a daemon because if application crashed the kernel driver should disable again the support for gestures.

Forget second finger. Forget multi touch. For multi touch you need multi point. For multi point you need MPX. For MPX you need X Server 1.7.x.

We are discussing gestures here.

Re: multitouch on N900
 

Ok, thanks for your replies.
I think that it will be worth it to create a POC to see how it works.

Will then ask about your opinions :)

Re: multitouch on N900
 

Just adding a suggestion here. How about doing just a workaround and have your left thumb press the Ctrl button. So, if the Ctrl button is pressed down, your right index finger, depending on the gesture, zooms or rotates?

If you think about it, when zooming or rotating on a capacitive screen, the thumb really doesn't do much.

Re: multitouch on N900
 

Yes, using keys for modifiers of gestures opens a plethora of possibilities, which is an advantage of having an an on-board keyboard.

However, this adds complexity.

Some comments/suggestions:

• In begin is in development but once deployed I suggest the modifiers be HIGged (so they are same in all applications). If every application uses same modifiers for gestures while outcome is different you don't have one learning curve; you suddenly have several.
• Find easiest modifier usability-wise, allow to be rebind to keep in mind left-hand users. I think Ctrl is easiest indeed. Bind (in this case Ctrl) must not be otherwise used in application, current focus, or OS. For example, imagine Ctrl is pressed, alternative gesture is used, while then used presses V. That means the current copied text is pasted. On a multimedia keyboard you can rebind your *** off. On N810/N900 not so.
• Let this bind enable to disable the 'following' by enabling the 'faster scanning of input on touchscreen input driver'. Although I think this already is enabled hence not required because already you can zoom in or out e.g. in Maemo Browser.
• If device in kickstand left hand is not necessarily near Ctrl (example is right-hand use-case). Minor issue but worth noting.

Re: n900 - multitouch
 

I think that's planned for Maemo6, not sure though.

Re: n900 - multitouch
 

hmm that looks pretty good

Re: n900 - multitouch
 

See this thread

Re: n900 - multitouch
 

if you can make a plugin for the whole device to use this feature that would be amazing. like in the image gallery and webpages. it could even work for games. isnt the firmware open sourse so maybe a plugin for the whole firmware???????

Re: multitouch on N900
 

im excited. i hope somthing good comes from this. then ill get my friends iphones's and spit on them lol

Re: multitouch on N900
 

Not possible to get Multitouch on N900, Since it was not built to be Multitouch and there is no hardware supporting such activity.

Re: n900 - multitouch
 

Please merge with Multitouch with N900. This is the same.

Re: multitouch on N900
 

lol. no this about fake multitouch. i know the n900 touchscreen is a single touch screen.

this is an example for the 5800.
http://www.youtube.com/watch?v=4dC2q...layer_embedded

this is just clever coding. but bassiclly it would be a two point touch device through clever software. this is one of the apps/plugin's i would acctually pay for and recommend if a developer created it for maemo5.

maybe have it as a mask over the whole interface which links to the volume keys that allow zooming in and out for certian apps. and have a disable and enable feature in the system shortcut section(the drop down box when you click on the time)


i know i couldnt code to that standard. This is something that would get the developer famous all over the internet

Re: multitouch on N900
 

Threads merged.

Re: multitouch on N900
 

Advantages

Resistive touchscreen technology works well with almost any stylus-like object. In some circumstances, this is more desirable than a capacitive touchscreen, which can be operated with only finger.

Costs are relatively low when compared with active touchscreen technologies.

Resistive touchscreen technology can be made to support multi-touch input.


source http://en.wikipedia.org/wiki/Resistive_touchscreen
can this be possible on n900?

Re: multitouch on N900
 

No, it requires hardware different from what the N900 uses.

Re: multitouch on N900
 

hi friends :) can I change display of my n900 with a resistive multitouch sensible-pressure display? Nokia technical center (or equivalent) can do that? (of course, paying!! ;) )
I'd like to have my n900 with this kind of hardware display!
thank you for your replies...
:)

Re: multitouch on N900
 

No, not really, not unless you're an uber hardware hacker. The connection between the screen and the rest of the device will likely be different, and you would likely need different chips within the device to run the screen. Then there's the lack of multi-touch in the OS and apps.

Re: multitouch on N900
 

Well apparently no one reads the thread before replying.

I think pseudo-multi touch would work but it would have several limitations. First of all, I am going to assume the software works like this:

1) default is single touch mode, remembering the last known position while the screen is being touched

2) if it detects a sudden change in location (faster than humanly possible to move your finger) then it will deduce that a second finger must have been used and the average value of the two touches is being "sensed". The two limitations here are that:

a) you have to put one finger before the other and
b) you have to put the fingers further apart than whatever distance is determined to be "too far" to move for a single finger in that time period

Once the software has determined that two fingers are being used, it is then going to switch to multi-touch mode.

3) If it detects another sudden change (2nd finger is lifted) then it will switch back to single touch mode. [I don't think 3-finger-touch will be possible]

As for the multi-touch mode, the software takes the currently detected location and, on the assumption that it is the average of two points, it can then simulate multi-touch. Obviously we cannot get two unknowns from just one equation so we must give it one fixed point. This means that the limitation for multi-touch gestures is that one finger (probably more intuitive to use the first finger which touched the screen) must not move.


So, to summarize:
I) Limited to two-touch
II) Must put one finger before the second
III) One finger must be stationary

This would still be useful for multi-touch gestures and could simulate the "pinch-zoom" everyone loves so much... just need to keep one finger still and pinch the other.

Re: multitouch on N900
 

It should be better a n900 with real multitouch display...