ScreenCapture QML Type

The ScreenCapture type is used for capturing a screen. More...

Import Statement: import QtMultimedia
Since: Qt 6.5
Instantiates: QScreenCapture


Detailed Description

ScreenCapture captures a screen. It is managed by MediaCaptureSession where the captured view can be displayed in a window 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.
  • It is unsupported on Linux with Wayland compositor, due to Wayland protocol restrictions and limitations.
  • 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. Capturing Widget-based applications works from Qt 6.5.5, and capturring Quick-based applications works from Qt 6.5.6. 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 CaptureSession.

Property Documentation

active : bool

Describes whether the capturing is currently active.

[read-only] error : enumeration

Returns a code of the last error.

[read-only] errorString : string

Returns a human readable string describing the cause of error.

screen : Screen

Describes the screen for capturing.

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