使用带有surfaceview和delay的API2启动相机预览

我在使用camera2api和surface view时遇到了一个问题。这是一个旧的嵌入式系统和我 有

我发现这个示例展示了如何实现:

https://android.googlesource.com/platform/frameworks/base/+/ee699a6/tests/Camera2Tests?autodive=0

我需要在“onCreate”之后延迟开始预览。这一准则毫不迟延地起作用。但是如果我添加一个延迟,预览就不会出现(surface回调就不会被调用)

这里有一段代码 不是

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.surfaceviewtest);

    new Handler(Looper.getMainLooper()).postDelayed(new Runnable() {
        @Override
        public void run() {
            startCameraExec();
        }
    }, 2000);
}

但是这个 作品 :

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.surfaceviewtest);
    startCameraExec();
}

我的startCameraExec只是设置了后台线程和surface回调

private void startCameraExec() {
    Log.d(TAG, "Starting API2 camera...");
    // Start a background thread to manage camera requests
    mBackgroundThread = new HandlerThread("background");
    mBackgroundThread.start();
    mBackgroundHandler = new Handler(mBackgroundThread.getLooper());
    mForegroundHandler = new Handler(getMainLooper());
    mCameraManager = (CameraManager) getSystemService(CAMERA_SERVICE);

    mSurfaceView = (SurfaceView) findViewById(R.id.mainSurfaceView);
    mSurfaceView.getHolder().addCallback(mSurfaceHolderCallback);
}

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@color/colorPrimary"
    android:orientation="vertical">

    <SurfaceView xmlns:android="http://schemas.android.com/apk/res/android"
        android:id="@+id/mainSurfaceView"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_alignParentTop="true"
        android:layout_centerInParent="true"
        android:layout_margin="80dp"
        android:onClick="onClickOnSurfaceView" />
</RelativeLayout>

这里是什么我认为是问题,这从来没有被称为如果延迟初始化

final SurfaceHolder.Callback mSurfaceHolderCallback = new SurfaceHolder.Callback() {

... a bunch of code
    @Override
    public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
        // On the first invocation, width and height were automatically set to the view's size
        if (mCameraId == null) {
            // Find the device's back-facing camera and set the destination buffer sizes
            try {
                for (String cameraId : mCameraManager.getCameraIdList()) {
                    CameraCharacteristics cameraCharacteristics =
            ... a bunch of code

谢谢您。