Problem

我的手机支持所有手动配置。测试用（https://github.com/pinguo-yuyidong/Camera2 https://github.com/pinguo-yuyidong/Camera2）这允许我们使用搜索栏进行调整。

我想在开始预览时在镜头焦距中设置固定值，直到关闭应用程序。

在我将自动对焦模式设置为关闭并设置镜头焦距后。预览没有显示任何效果，但 Focus 2 值发生了变化。

我怎样才能克服这个问题？

示例代码（Java）

    private CaptureRequest mPreviewRequest;
    private void startCameraPreview() throws CameraAccessException {
        SurfaceTexture texture = textureview.getSurfaceTexture();
        texture.setDefaultBufferSize(imageDimensions.getWidth(), imageDimensions.getHeight());
        Surface surface = new Surface(texture);
        mPreviewRequestBuilder = cameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_PREVIEW);
        mPreviewRequestBuilder.addTarget(surface);
        System.out.println("Focus 1 ====== "+mPreviewRequestBuilder.get(CaptureRequest.LENS_FOCUS_DISTANCE));
        cameraDevice.createCaptureSession(Arrays.asList(surface), new CameraCaptureSession.StateCallback() {
            @Override
            public void onConfigured(@NonNull CameraCaptureSession session) {
                if (cameraDevice == null) {
                    return;
                }
                cameraSession = session;

                try {
                    mPreviewRequestBuilder.set(CaptureRequest.CONTROL_AF_MODE,CaptureRequest.CONTROL_AF_MODE_OFF);
                    mPreviewRequestBuilder.set(CaptureRequest.LENS_FOCUS_DISTANCE, 7.5f);
                    mPreviewRequest = mPreviewRequestBuilder.build();
                    cameraSession.setRepeatingRequest(mPreviewRequest, mCaptureCallback, backgroundHandler);
                    System.out.println("Focus 2 ====== "+mPreviewRequestBuilder.get(CaptureRequest.LENS_FOCUS_DISTANCE));
                } catch (CameraAccessException e) {
                    e.printStackTrace();
                }
            }
            @Override
            public void onConfigureFailed(@NonNull CameraCaptureSession session) {
                Toast.makeText(getApplicationContext(),"Failed",Toast.LENGTH_SHORT).show();
            }
        }, null);
    }
    
    private static final int STATE_PREVIEW = 0;
    private int mState = STATE_PREVIEW;
    private CameraCaptureSession.CaptureCallback mCaptureCallback = new CameraCaptureSession.CaptureCallback() {
        private void process(CaptureResult result){
            switch(mState){
                case STATE_PREVIEW:{
                    break;
                }
            }
        }
    };

Output

焦点 1 ====== 0.0

焦点2 ====== 7.5

当我改变值时我看不出有什么区别。

找到了答案

不知道为什么我需要 mPreviewRequest 和 setRepeatingRequest 2 次，但它有效。

mPreviewRequestBuilder.set(CaptureRequest.CONTROL_AF_MODE,CaptureRequest.CONTROL_AF_MODE_OFF);
mPreviewRequest = mPreviewRequestBuilder.build();
cameraSession.setRepeatingRequest(mPreviewRequest, mCaptureCallback, backgroundHandler);
mPreviewRequestBuilder.set(CaptureRequest.LENS_FOCUS_DISTANCE, 7.5f);
mPreviewRequest = mPreviewRequestBuilder.build();
cameraSession.setRepeatingRequest(mPreviewRequest, mCaptureCallback, backgroundHandler);