在Android上使用Qt C ++截图

Question

thanks for checking my question out!

I'm currently working on a project using Qt C++, which is designed to be multi-platform. I'm a bit of a newcoming to it, so I've been asked to set up the ability to take screenshots from within the menu structure, and I'm having issues with the Android version of the companion app.

As a quick overview, it's a bit of software that send the content of a host PC's screen to our app, and I've been able to take screenshots on the Windows version just fine, using QScreen and QPixmap, like so:

overlaywindow.cpp

{
    QPixmap screenSnapData = screenGrab->currentBackground();
}

screenGrabber.cpp

{
    QScreen *screen = QGuiApplication::primaryScreen();
    return screen->grabWindow( QApplication::desktop()->winId() );
}

Unfortunately, Android seems to reject QScreen, and with most suggestions from past Google searches suggesting the now-deprecated QPixmap::grab(), I've gotten a little stuck.

What luck I have had is within the code for the menu itself, and QWidget, but that isn't without issue, of course!

QFile doubleCheckFile("/storage/emulated/0/Pictures/Testing/checking.png");
doubleCheckFile.open(QIODevice::ReadWrite);
QPixmap checkingPixmap = QWidget::grab();
checkingPixmap.save(&doubleCheckFile);
doubleCheckFile.close();

This code does take a screenshot, but only of the button strip currently implemented, and not for the whole screen. I've also taken a 'screenshot' of just a white box with the screen's dimensions by using:

QDesktopWidget dw;
QWidget *screen=dw.screen();         
QPixmap checkingPixmap = screen->grab();

Would anyone know of whether there was an alternative to using QScreen to take a screenshot in Android, or whether there's a specific way to get it working as compared to Windows? Or would QWidget be the right track? Any help's greatly appreciated!

Answer 1

as i can read in Qt doc : In your screenGrabber.cpp :

QScreen *screen = QGuiApplication::primaryScreen();
return screen->grabWindow( QApplication::desktop()->winId() );

replace with :

QScreen *screen = QGuiApplication::primaryScreen();
return screen->grabWindow( 0 ); // as 0 is the id of main screen

Answer 2

If you want to take a screenshot of your own widget, you can use the method QWidget::render ( Qt Doc ):

QPixmap pixmap(widget->size());
widget->render(&pixmap);

If you want to take a screenshot of another app/widget than your app, you should use the Android API...