qt调用android原生接口,Qt for Android 调用原生系统摄像头进行录像并保存输出

要在Qt for Android中调用原生系统摄像头进行录像并保存输出，可以使用Android NDK来实现。下面是实现步骤：

1. 在Qt项目中添加一个Java文件，文件名为CameraRecorder.java，代码如下：

package com.example.myapplication;

import android.hardware.Camera;
import android.media.CamcorderProfile;
import android.media.MediaRecorder;
import android.os.Environment;
import android.util.Log;
import android.view.SurfaceHolder;

import java.io.File;
import java.io.IOException;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.List;

public class CameraRecorder implements SurfaceHolder.Callback {
    private static final String TAG = "CameraRecorder";

    private Camera mCamera;
    private MediaRecorder mMediaRecorder;
    private SurfaceHolder mHolder;

    private boolean mIsRecording = false;

    public CameraRecorder(SurfaceHolder holder) {
        mHolder = holder;
        mHolder.addCallback(this);
    }

    public void startRecording() {
        if (mCamera == null) {
            mCamera = getCameraInstance();
        }

        try {
            mCamera.setPreviewDisplay(mHolder);
            mCamera.startPreview();
        } catch (IOException e) {
            Log.e(TAG, "Error starting camera preview: " + e.getMessage());
        }

        mMediaRecorder = new MediaRecorder();
        mCamera.unlock();
        mMediaRecorder.setCamera(mCamera);

        mMediaRecorder.setAudioSource(MediaRecorder.AudioSource.CAMCORDER);
        mMediaRecorder.setVideoSource(MediaRecorder.VideoSource.CAMERA);

        CamcorderProfile profile = CamcorderProfile.get(CamcorderProfile.QUALITY_HIGH);
        mMediaRecorder.setProfile(profile);

        SimpleDateFormat dateFormat = new SimpleDateFormat("yyyyMMdd_HHmmss");
        String currentDateAndTime = dateFormat.format(new Date());
        File mediaFile = new File(Environment.getExternalStorageDirectory().getAbsolutePath() + "/DCIM/Camera/", "VID_" + currentDateAndTime + ".mp4");
        mMediaRecorder.setOutputFile(mediaFile.getAbsolutePath());

        try {
            mMediaRecorder.prepare();
        } catch (IOException e) {
            Log.e(TAG, "Error preparing media recorder: " + e.getMessage());
        }

        mMediaRecorder.start();
        mIsRecording = true;
    }

    public void stopRecording() {
        if (mIsRecording) {
            mMediaRecorder.stop();
            mMediaRecorder.release();
            mCamera.lock();
            mCamera.release();
            mCamera = null;
            mIsRecording = false;
        }
    }

    private Camera getCameraInstance() {
        Camera camera = null;
        try {
            camera = Camera.open();
        } catch (Exception e) {
            Log.e(TAG, "Error opening camera: " + e.getMessage());
        }

        if (camera != null) {
            Camera.Parameters params = camera.getParameters();
            List<Camera.Size> sizes = params.getSupportedPreviewSizes();
            Camera.Size size = sizes.get(0);
            params.setPreviewSize(size.width, size.height);
            camera.setParameters(params);
        }

        return camera;
    }

    @Override
    public void surfaceCreated(SurfaceHolder holder) {

    }

    @Override
    public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {

    }

    @Override
    public void surfaceDestroyed(SurfaceHolder holder) {
        stopRecording();
    }
}

2. 在Qt项目的AndroidManifest.xml文件中添加如下权限：

<uses-permission android:name="android.permission.CAMERA"/>
<uses-permission android:name="android.permission.RECORD_AUDIO"/>
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>

3. 在Qt项目中添加一个QML页面，页面中添加一个SurfaceView控件，并在控件上叠加一个按钮，代码如下：

import QtQuick 2.0
import QtQuick.Controls 1.4
import QtQuick.Layouts 1.2
import QtQuick.Dialogs 1.2
import QtAndroidExtras 1.4

Rectangle {
    id: root
    width: 360
    height: 640
    color: "white"

    SurfaceView {
        id: surfaceView
        anchors.fill: parent
    }

    Button {
        id: btnRecorder
        text: "Start Recording"
        width: 200
        height: 50
        anchors.centerIn: parent
        onClicked: {
            if (btnRecorder.text === "Start Recording") {
                var recorder = QtAndroid.createQmlObject('import com.example.myapplication 1.0; CameraRecorder {id: recorder;}', surfaceView);
                recorder.startRecording();
                btnRecorder.text = "Stop Recording";
            } else {
                recorder.stopRecording();
                btnRecorder.text = "Start Recording";
            }
        }
    }
}

4. 编译并运行Qt项目，在页面中点击按钮即可开始录制视频。视频文件保存在SD卡的DCIM/Camera目录下。

以上代码仅为示例代码，具体实现可以根据自己的需求进行修改。