ScreenCapture QML Type

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

Import Statement: import QtMultimedia
Since: Qt 6.5
In C++: QScreenCapture


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 limitation. 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). This limitation might change in the future.
  • It is not supported on mobile operating systems, except on Android. There, you might run into performance issues as the class is currently implemented via QScreen::grabWindow, which is not optimal for the use case.
  • 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

active : bool

Describes whether the capturing is currently active.

error : enumeration [read-only]

Returns a code of the last error.

errorString : string [read-only]

Returns a human readable string describing the cause of error.

screen : Screen

Describes the screen for capturing.

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