Qt 6.5中ScreenCapture设置window属性报错，是Bug还是操作有误？

你的问题不是Qt 6.5的Bug，也不是遗漏操作——Qt 6.5的QML版ScreenCapture类确实没有window属性，该属性是从Qt 6.6开始才新增的。你看到的官方文档大概率对应更高版本，因此出现了版本不匹配的问题。

两种解决路径： #

1. 升级到Qt 6.6及以上版本 #

如果允许升级Qt版本，直接升级后，修改代码即可实现指定窗口捕获：

ApplicationWindow {
  id: root
  visible: true
  width: 640
  height: 480

  MouseArea {
    id: recording
    anchors.fill: parent
    property bool inProcess: false
    onClicked: {
      if (recording.inProcess) {
        screenCapture.active = recording.inProcess = false;
        recorder.stop();  
      } else {
        screenCapture.active = recording.inProcess = true;
        recorder.record();
      }
    }
  }

  CaptureSession {
    id: captureSession
    screenCapture: ScreenCapture {
      id: screenCapture
      active: false
      window: root // 升级到Qt6.6+后可正常使用该属性
    }
    recorder: MediaRecorder {
      id: recorder
      mediaFormat {
        fileFormat: MediaFormat.MPEG4
        videoCodec: MediaFormat.VideoCodec.H265
      }
      outputLocation: "desired-name.mp4"
      quality: MediaRecorder.HighQuality
    }
  }
}

2. 在Qt 6.5中通过C++桥接实现指定窗口捕获 #

如果无法升级Qt版本，需要通过C++代码将ScreenCapture的窗口设置能力暴露给QML：

步骤1：创建C++辅助类

#include <QObject>
#include <QScreenCapture>
#include <QWindow>

class ScreenCaptureHelper : public QObject
{
    Q_OBJECT
public:
    explicit ScreenCaptureHelper(QObject *parent = nullptr) : QObject(parent) {}

    Q_INVOKABLE void setCaptureWindow(QScreenCapture *capture, QWindow *window) {
        if (capture && window) {
            capture->setWindow(window);
        }
    }
};

步骤2：在main.cpp中注册类到QML

#include <QGuiApplication>
#include <QQmlApplicationEngine>
#include "ScreenCaptureHelper.h"

int main(int argc, char *argv[])
{
    QGuiApplication app(argc, argv);

    qmlRegisterType<ScreenCaptureHelper>("com.example", 1, 0, "ScreenCaptureHelper");

    QQmlApplicationEngine engine;
    const QUrl url(u"qrc:/main.qml"_qs);
    QObject::connect(&engine, &QQmlApplicationEngine::objectCreated,
                     &app, [url](QObject *obj, const QUrl &objUrl) {
        if (!obj && url == objUrl)
            QCoreApplication::exit(-1);
    }, Qt::QueuedConnection);
    engine.load(url);

    return app.exec();
}

步骤3：修改QML代码调用辅助类

import QtQuick
import QtQuick.Window
import QtMultimedia
import com.example 1.0

ApplicationWindow {
  id: root
  visible: true
  width: 640
  height: 480

  ScreenCaptureHelper {
    id: captureHelper
  }

  MouseArea {
    id: recording
    anchors.fill: parent
    property bool inProcess: false
    onClicked: {
      if (recording.inProcess) {
        screenCapture.active = recording.inProcess = false;
        recorder.stop();  
      } else {
        // 通过辅助类设置捕获窗口
        captureHelper.setCaptureWindow(screenCapture, root)
        screenCapture.active = recording.inProcess = true;
        recorder.record();
      }
    }
  }

  CaptureSession {
    id: captureSession
    screenCapture: ScreenCapture {
      id: screenCapture
      active: false
    }
    recorder: MediaRecorder {
      id: recorder
      mediaFormat {
        fileFormat: MediaFormat.MPEG4
        videoCodec: MediaFormat.VideoCodec.H265
      }
      outputLocation: "desired-name.mp4"
      quality: MediaRecorder.HighQuality
    }
  }
}

内容的提问来源于stack exchange，提问作者excommunicado