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• ScreenCapture

ScreenCapture

This type is used for capturing a screen. More...

• List of all members, including inherited members

Properties

• active : bool
• error : enumeration
• errorString : string
• screen : Screen

Detailed Description

ScreenCapture captures a screen. It is managed by MediaCaptureSession where the captured screen can be displayed in a video preview object or recorded to a file.

The code below shows a simple capture session with ScreenCapture playing back the captured primary screen view in VideoOutput.

CaptureSession {
    id: captureSession
    screenCapture: ScreenCapture {
        id: screenCapture
        active: true
    }
    videoOutput: VideoOutput {
        id: videoOutput
    }
}

Screen Capture Limitations

On Qt 6.5.2 and above, the following limitations apply to using ScreenCapture:

• It is only supported with the FFmpeg backend.
• On Linux systems using the Wayland compositor, the screen capture implementation is experimental and comes with the following limitations. Due to restrictions of the Wayland protocol, it's impossible to set and get the target screen via the API of the QScreenCapture class. Instead, the OS will show a screen selection wizard upon invoking QScreenCapture::setActive(true). The screen capture feature requires the installation of the ScreenCast service supported via XDG Desktop Portal and {https://pipewire.org/}{PipeWire} (0.3). These limitations might change in the future.
• It is not supported on mobile operating systems, except on Android. Screen Capture on Android needs additional Android foreground service permission to be added to the AndroidManifest.xml file:

  <manifest ...>
  <uses-permission android:name="android.permission.FOREGROUND_SERVICE" />
  <uses-permission android:name="android.permission.FOREGROUND_SERVICE_MEDIA_PROJECTION" />
  <application ...>
      <service android:name="org.qtproject.qt.android.multimedia.QtScreenCaptureService"
          android:foregroundServiceType="mediaProjection"
          android:exported="false"/>
      </service>
  </application>
  </manifest>

• On embedded with EGLFS, it has limited functionality. For Qt Quick applications, the class is currently implemented via QQuickWindow::grabWindow, which can cause performance issues.
• In most cases, we set a screen capture frame rate that equals the screen refresh rate, except on Windows, where the rate might be flexible. Such a frame rate (75/120 FPS) might cause performance issues on weak CPUs if the captured screen is of 4K resolution. On EGLFS, the capture frame rate is currently locked to 30 FPS.

See also WindowCapture and CaptureSession.

Property Documentation