Touchscreen bounces with Qt app.

[bask185]

Today I got a new panel PC, I believe it may be the cheapest one available. The thing has an Ltd eGalax touchscreen and with Ubuntu 16.04 LTS installed it works out of the box like a charm.

But when I run my Qt application, the touchscreen bounces.....alot. When I boot to the desktop there seems to be no problem at all. The virtual keyboard of ubuntu also works perfect. My fancy Qtumbler does not work now :(

My application is run on it's own desktop (so it can run fullscreen).

I do not know where the problem might be. The problem might be related to Qt (5.8) or it might related to the separate desktop. But I have no way to test this.

I don't know if there are any known issues between Qt apps and certain touchscreen drivers??

[raven-worx]

@bask185 said in Touchscreen bounces with Qt app.:

But when I run my Qt application, the touchscreen bounces.....alot.

what exactly does this mean?

[bask185]

I mean it bounces just like a bouncing switch. When I hold my finger on a pushbutton (yes, autorepeat is disabled), I see the state toggling and events are being executed continously instead of just one time. This prevents me from using the Qtumbler :(

[bask185]

So nobody has a clue why Qt on this systems behaves like this?

[SGaist]

Hi,

Do you have the same strange behaviour if you compile your application your distribution provided Qt ?

[bask185]

@SGaist No I only have it on this particular panel PC. The PC has ubuntu installed like my host pc and other panel PCs

Unfortunately this thing must be shipped out as a pilot. So I have to fix the flickering. I tried using QThread::msleep(); but that does not solve the problem it only makes it slower.

If I push a button and the msleep is set at 300ms I am still getting 3 events instead of just 1.

I think I came up with a viable simple solution. When I push a button I want to set a boolean variable true and let it go to false after a time has expired. When the boolean is set to true, no actions will happen.

example:

void on_pushbutton_clicked()
{
   if(boolean == false) {

}

}

[SGaist]

Usually de-bouncing is done using a single shot timer that is connected to the actual slot that will do something.