Hello World touchscreen-program

Assuming F14 means Fedora 14, I would start by looking at the sources for some simple graphical application, such as a calculator, or the demo programs available for the various GUI/widget building systems. You already choose one, right? ( Gnome/KDE/QT/WxWidgets/FLTK ...)

If F14 means the F14 Tomcat fighter, you probably should ask somewhere else. (Pity, this would be more closely related to embedded systems.)

-- Roberto Waltman

Which touchscreen are you using? What does the datasheet for that touchscreen say?

Thanks Roberto for the reply.

I am sorry for the incomplete information. I meant Fedora 14.

Also, selecting a GUI system is not a big deal; so is the popping of the message. What I require help in is implementing the touch-sense- events. (This is what I meant when I said that the first and third stages are doable.)

Thanks again for the reply, but my query still remains purely unsolved.

Regards, Ajay

Thanks Rich for the reply.

Well, I have a normal Dell Laptop ( with no tuchscreen capability I guess.. :-| )

So, you mean, that

a. the touchscreen facility needs help from hardware (i.e. a touchscreen-screen ) ? b. if answer to a. is true, and if and when I am able to get hold of a touchscreen-screen, the (firmware) touch-sense-events API will be provided ?

I may well be absolute dumb; but I guess its ok to get the basics asked right at the beginning, than to have hollow knowledge later. :-|

Regards, Ajay

Yes, "a" is true. There are aftermarket touchscreen overlay kits that can be added to an existing display. I have not used any of them but here is one example from a quick Google search:

Nowadays, I'd expect this type to interface via USB and act "like a mouse" as far as the operating system is aware.

Not many do..

Maybe you should start looking at the existing kits with say, a capacitive touch screen/VGA/vid controller/micro controller package?

Say something like

And then read up on its documentation, APIs, example code, etc. etc.

OK, I misunderstood the question. The "right" question seems to be along the lines of "How to integrate a touch screen with an existing Linux system with no touch capability"

As Rich pointed out, there are some touch screens that already provide a "mouse-like" serial or USB interface. Some are add-on's, other are integrated with a display (for example,

So,

a) If not done already, select a touch screen b) If it does not provide a recognized interface to Linux, you need to: b.1) Mechanically / electrically interface it to your system b.2) Write / adapt / port a Linux driver to control the touch screen.

Everything else should be doable from user land applications. My original suggestion to look at existing systems still applies. Look at Linux distributions for mobile devices, many of which have touch screen interfaces.

-- Roberto Waltman

The one time I did this was with Debian 5 in an appliance, using a COTS touchscreen as the console. We installed X-Window, then wrote a little Tcl/Tk app, using the native widgets, and it just worked.

Mel.

Or, depending on how deeply the touchscreen manufacturer expects that you're going to be integrating, it may come with a developers kit, or it may just state what it is and expect you to know.

Be sure to have certain places on the screen where it says "Hey, bub -- touch me _there_ again and I'm calling a lawyer!"

You haven't specified what sort of touch API you need.

E.g., something that just treats "static touches" as "mouse clicks" is very different from one that allow you to *drag* a touch across the screen... which is different from one that supports multiple concurrent touches... which is different from one that adds pressure sensitivity...

Assuming the simplest case (i.e., mouse clicks), the easiest way to do this is to have the touch screen/panel driver sit below the mouse interface and just report {X,Y,click} events through that interface.

The advantage of this is that you can write your app assuming a more traditional mouse interface and test and debug it using such!

(Hint: many vendors provide this sort of interface with their hardware)

Don't be lulled, however, into treating the touch panel *as* a mouse in your UI paradigm as there are subtle differences in how a human interacts with each which will constrain what you can/can't do in the interface.

Also, it is almost essential that you provide a mechanism that doesn't rely on a "calibrated" touch panel to invoke the "calibration" mechanism! As well as a means by which you can do other "important things" in the presence of a defective/uncalibrated touch panel!

Finally, be sure to carefully evaluate the actual touch screen technology that you deploy as each have liabiilties that you may need to address in your application. (personally, I prefer SAW on glass)

HTH

Thanks Rich, Doug, Roberto, Mel, Tim, D Yuniskis. I feel obliged for all the responses. :-)

I will have to digest this a bit, run to my local electronics-market, and evaluate the possibilities. Will definitely keep you posted guys.

And yes Tim, I will keep such areas. That will be the motivation to make the touchscreen absolutely sensitive and the best in the world ;- p ;-p ;-p ;-p

Thanks again everyone. Will keep you posted.

Regards, Ajay

Ajay Garg skrev 2011-11-08 14:33:

You need to decide which H/W to use. Your laptop does not have a touch capable screen, so you need to interface to something else. How about a Phone or a Tablet.

Do you have to write for Fedora? Why not write for an operating system which is built for Touch. iOS or Android are obvious choices. You can also get ready made Software Development Kits.

The app will run on your tablet/phone.

It toook me a couple of hours with the Android SDK to do what you want to do and download to my Galaxy Tab

Ubuntu has a new interface called Ubuntu One. This is going to support touch at one stage, maybe already now (I disabled it in favour of Gnome).