PhonOn displays at the only one monitor in a dual monitor system.

[SGaist]

You have two monitors, so if you want your widget to appear on your second monitor, you have to move it there. i.e. set its position to be in your secondary screen QDesktopWidget. You can get that using QDesktopWidget::screenGeometry

QDesktopWidget *desktopWidget = qApp->desktop();
QRect secondScreenGeometry = desktopWidget->screenGeometry(1);
myWidget->move(secondScreenGeometry.center());

[twoplus]

@SGaist I think there is misunderstanding. I want to display video that displaying area is 2000x700. So the video is displayed in the monitor1(1600x900) and monitor2(1920x1080), not monitor1 or monitor2. My problem is the area of monitor1 displays video well but the area of monitor2 only display black screen.

[SGaist]

Ok, indeed, there was a misunderstanding. So if you move your widget to your second monitor, it gets black or just the part when the widget is first shown ?

[twoplus]

@SGaist Displayed video size(area) is 2000x700. So I should use from (100,100) of monitor1 to (500,800) of monitor2. In other words monitor1 display 1500x700 of video and monitor2 display 500x700 of video at the same time. But monitor1 displays well but monitor2 displays black. So some area(monitor2) of video is shown black.

[SGaist]

What happens if you have the complete video widget on the secondary screen ?

[twoplus]

@SGaist Then PhonOn displays the vidoe well.

[SGaist]

Are both your screen "standard" ? Meaning not one being retina

[twoplus]

@SGaist Yes, my screens are standard.

[SGaist]

I just realized, Qt 4.6.2 ? You should at least go to 4.8.7

[twoplus]

@SGaist Thank you for your help. Do you mean the PhonOn of 4.6.2 doesn't work but 4.8.7 works well in this case?

[SGaist]

No, I mean that Qt 4.6.2 is pretty outdated so you should at least use the latest version available of the Qt 4 series (note that 4.8.7 is the last version of the Qt 4 series).

[Sprezzatura]

@SGaist Not working for me (Qt 5.13).

[SGaist]

@Sprezzatura said in PhonOn displays at the only one monitor in a dual monitor system.:

@SGaist Not working for me (Qt 5.13).

Well, with that much details, it's going to be a bit hard to help.