Change Viewfinder Resolution in qt C++

Praveen k · wrote on 13 Oct 2016, 06:49

Hey Guys!!!! Once again in trouble. I am trying to change viewfinder resolution at run time but unfortunately, application is closing..
Let me explain you in detail:-

Initially i am setting my viewfinder resolution to the last supported viewfinder resolutions (say 1280 x 720) and then with the help of combo box i am selecting another resolution (say 640 x 480)
After selecting another resolution, my program is finishing unexpectedly.

Anybody with the solution please.. Regrets for silly mistakes.
Here is the sample snippet....

mCameraViewFinder = new QCameraViewfinder;
mCameraImageCapture = new QCameraImageCapture(mCamera,this);

    mCamera->start();
    QList<QSize> res = mCamera->supportedViewfinderResolutions();
     QSize selectedRes;
        if(!res.isEmpty())
        {
            selectedRes = res.takeLast();
        }
        else
        {
             qDebug()<<"Empty Resolution!!!";
        }
    viewfindersettings.setResolution(selectedRes);
//Here current resolution is 1280*720 
    mCamera->setViewfinderSettings(viewfindersettings);

//After selecting resolution from combo box
    viewfindersettings.setResolution(n,n1);
//Here n and n1 are 640 and 480 respectively
    mCamera->setViewfinderSettings(viewfindersettings);
    mCamera->setViewfinder(ui->viewfinder);
    mCamera->start();

Need some help...

SGaist · wrote on 13 Oct 2016, 21:22

Hi,

What does a run through the debugger tell you ?

Praveen k · wrote on 14 Oct 2016, 06:38

It is pointing to this error:-

 mCamera->setViewfinderSettings(viewfindersettings);

Giving me Segmentation fault. And the value in (this) is 0x0 of type camera*

SGaist · wrote on 14 Oct 2016, 07:14

Do you mean that mCamera is a null pointer ?

Praveen k · wrote on 14 Oct 2016, 07:59

No. I have initialized.

SGaist · wrote on 14 Oct 2016, 13:38

Can you post an image of the stack trace ?

See the guide here for posting picture as the upload is currently broken.

Praveen k · wrote on 15 Oct 2016, 05:50

This post is deleted!

Praveen k · wrote on 15 Oct 2016, 05:56

https://drive.google.com/open?id=0B27_ICxFo-UcaE9icWx3UTBZcmM

p3c0 · wrote on 15 Oct 2016, 06:01

@Praveen-k Use some other site where login is not required.
https://postimage.org
http://tinypic.com

Praveen k · wrote on 15 Oct 2016, 06:05

I tried as @SGaist guided for posting pictures on forum. But unfortunately itz not posting. So here you can get it
https://postimg.org/image/x3po0e1lf

SGaist · wrote on 15 Oct 2016, 20:26

The camera object itself seems to be null. Are you sure it's initialized correctly ?

Praveen k · wrote on 17 Oct 2016, 05:35

Ok. if i have not initialized it, can you help me on how to initialize it?
I have done the initialization as below:

    mCamera = new QCamera(this);
    mCameraViewFinder = new QCameraViewfinder(this);
    mCameraImageCapture = new QCameraImageCapture(mCamera,this);
    mCamera->start();

SGaist · wrote on 17 Oct 2016, 06:46

It's not your mCamera object that is null, it's your camera object.

Praveen k · wrote on 17 Oct 2016, 07:13

How can i initialize it? Plz help me

SGaist · wrote on 17 Oct 2016, 07:20

It's your own custom class, how can I know where you use it or how you use it ?

Praveen k · wrote on 17 Oct 2016, 07:26

Sorry.. I got it. Thanks for the solution man. Silly mistake from my side..
But after initializing new camera is starting. Wat if, i want the previous one

SGaist · wrote on 17 Oct 2016, 07:56

Then don't create a new QCamera each time you change the resolution.