Android 相机 2 API setRepeatingRequest

Question

我正在使用 camera2 制作 android 相机应用。我的代码与官方 camera2 示例几乎相同，但将片段传输到 activity。我计划将缩放设置为默认参数，以便在 openCamera(w, h) 中实现缩放功能。下面是我设置相机默认缩放的代码。

private void openCamera(int width, int height) {
    if (ContextCompat.checkSelfPermission(this, Manifest.permission.CAMERA) != PackageManager.PERMISSION_GRANTED) {
        requestCameraPermission();
        return;
    }
    setUpCameraOutputs(width, height);
    configureTransform(width, height);
    Activity activity = this;
    CameraManager manager = (CameraManager) activity.getSystemService(Context.CAMERA_SERVICE);
    try {
        if (!cameraOpenCloseLock.tryAcquire(2500, TimeUnit.MILLISECONDS)) {
            throw new RuntimeException("Time out waiting to lock camera opening.");
        }
        manager.openCamera(cameraId, stateCallback, backgroundHandler);
    } catch (CameraAccessException e) {
        e.printStackTrace();
    } catch (InterruptedException e) {
        throw new RuntimeException("Interrupted while trying to lock camera opening.", e);
    }

    try{
        CameraCharacteristics characteristics = manager.getCameraCharacteristics(cameraId);
        float maxzoom = (characteristics.get(CameraCharacteristics.SCALER_AVAILABLE_MAX_DIGITAL_ZOOM));
        android.graphics.Rect m = characteristics.get(CameraCharacteristics.SENSOR_INFO_ACTIVE_ARRAY_SIZE);
        float zoomLevel = maxzoom/3;
        float ratio = (float) 1/zoomLevel;
        int cropWidth = m.width() - Math.round((float)m.width()*ratio);
        int cropHeight = m.height() - Math.round((float)m.height()*ratio);
        android.graphics.Rect zoom = new android.graphics.Rect(cropWidth/2, cropHeight/2, m.width() - cropWidth/2, m.height() - cropHeight/2);
        previewRequestBuilder.set(CaptureRequest.SCALER_CROP_REGION, zoom);
        try{
            captureSession.setRepeatingRequest(previewRequestBuilder.build(), captureCallback, null); // Null Exception occur
        } catch (CameraAccessException e) {
            e.printStackTrace();
        } catch (NullPointerException ex) {
            ex.printStackTrace();
        }
    } catch (CameraAccessException e) {
        throw new RuntimeException("can not access camera.", e);
    }

}

变焦和相机没有问题。但是，当我第一次使用 android studio 和运行应用程序安装我的应用程序时，它总是在 setreapeatingrequest() 处出现空点异常。再尝试 2 或 3 次后，应用运行就可以了。我怀疑这个异常可能会发生，因为没有预览或其他东西。但我不知道如何解决这个错误。任何意见都必须非常有帮助。提前致谢。

Answer 1

有点晚了但是对于那些担心的人，我自己修复了这个错误。检查这个：

delayHandler.postDelayed(new Runnable() {
        @Override
        public void run() {
            try {
                CameraCharacteristics characteristics = manager.getCameraCharacteristics(cameraId);
                float maxzoom = (characteristics.get(CameraCharacteristics.SCALER_AVAILABLE_MAX_DIGITAL_ZOOM));
                android.graphics.Rect m = characteristics.get(CameraCharacteristics.SENSOR_INFO_ACTIVE_ARRAY_SIZE);
                float zoomLevel = maxzoom / 6;
                float ratio = (float) 1 / zoomLevel;
                int cropWidth = m.width() - Math.round((float) m.width() * ratio);
                int cropHeight = m.height() - Math.round((float) m.height() * ratio);
                android.graphics.Rect zoom = new android.graphics.Rect(cropWidth / 2, cropHeight / 2, m.width() - cropWidth / 2, m.height() - cropHeight / 2);
                previewRequestBuilder.set(CaptureRequest.SCALER_CROP_REGION, zoom);
                try {
                    captureSession.setRepeatingRequest(previewRequestBuilder.build(), captureCallback, null);
                } catch (CameraAccessException e) {
                    e.printStackTrace();
                } catch (NullPointerException ex) {
                    ex.printStackTrace();
                }
            } catch (CameraAccessException e) {
                throw new RuntimeException("can not access camera.", e);
            }
        }
    }, 500);

因为我制作了camea来变焦，所以准备相机需要一些时间。在我让相机在 500 毫秒延迟后打开后，它完美无误地工作。

Android 相机 2 API setRepeatingRequest

Android Camera2 API setRepeatingRequest

camera

android