Android相机视图未打开

Question

我正在开发一个Android应用程序。我在其中使用相机捕捉图像。我使用以下代码打开相机。问题是，执行 camera = Camera.open（cameraId）后相机视图未打开。单击“制作照片”后，只有相机指示灯打开（相机视图仍未打开）。如何显示相机视图？

在MakePhotoActivity.java中，

@Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        // do we have a camera?
        if (!getPackageManager()
                .hasSystemFeature(PackageManager.FEATURE_CAMERA)) {
            Toast.makeText(this, "No camera on this device", Toast.LENGTH_LONG)
                    .show();
        } else {
            cameraId = findFrontFacingCamera();
            if (cameraId < 0) {
                Toast.makeText(this, "No front facing camera found.",
                        Toast.LENGTH_LONG).show();
            } else {
                camera = Camera.open(cameraId);
            }
        }
    }

 public void onClick(View view) {
        camera.takePicture(null, null,
                new PhotoHandler(getApplicationContext()));
    }

在main.xml中，

<?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" >

    <Button
        android:id="@+id/captureFront"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerInParent="true"
        android:onClick="onClick"
        android:text="Make Photo" />

</RelativeLayout> 

Answer 1

此代码有帮助吗？

这适用于前置摄像头。

import android.hardware.Camera;
import android.hardware.Camera.CameraInfo;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Toast;

public class VideoFragment extends Fragment {

private static final String TAG = "VideoFragment";
private SurfaceView preview;
private SurfaceHolder previewHolder;
private Camera camera = null;
private boolean cameraConfigured = false;
private boolean inPreview = false;
private int frontFacingCameraID;

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    frontFacingCameraID = findFrontFacingCamera();
}

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
        Bundle savedInstanceState) {

    View view = inflater.inflate(R.layout.video, container, false);

    preview = (SurfaceView) view.findViewById(R.id.surfaceView1);
    previewHolder = preview.getHolder();
    previewHolder.addCallback(surfaceCallback);

    return view;
}

private int findFrontFacingCamera() {
    int cameraId = -1;
    // Search for the front facing camera
    int numberOfCameras = Camera.getNumberOfCameras();
    for (int i = 0; i < numberOfCameras; i++) {
        CameraInfo info = new CameraInfo();
        Camera.getCameraInfo(i, info);
        if (info.facing == CameraInfo.CAMERA_FACING_FRONT) {
            Log.d(TAG, "Camera found");
            cameraId = i;
            break;
        }
    }
    return cameraId;
}

@Override
public void onResume() {
    super.onResume();

    camera = Camera.open(frontFacingCameraID);
    startPreview();
}

@Override
public void onPause() {
    if (inPreview) {
        camera.stopPreview();
    }

    camera.release();
    camera = null;
    inPreview = false;

    super.onPause();
}

private SurfaceHolder.Callback surfaceCallback = new SurfaceHolder.Callback() {

    @Override
    public void surfaceDestroyed(SurfaceHolder holder) {
        // no-op
    }

    @Override
    public void surfaceCreated(SurfaceHolder holder) {
        // no-op -- wait until surfaceChanged()
        // TODO understand why this has to be NO-OP

    }

    @Override
    public void surfaceChanged(SurfaceHolder holder, int format, int width,
            int height) {
        // TODO understand why these methods have to be called in this
        // callback method
        initPreview(width, height);
        startPreview();
    }
};

private void initPreview(int width, int height) {
    if (camera != null && previewHolder.getSurface() != null) {
        try {
            camera.setPreviewDisplay(previewHolder);
        } catch (Throwable t) {
            Log.e("PreviewDemo-surfaceCallback",
                    "Exception in setPreviewDisplay()", t);
            Toast.makeText(getActivity(), t.getMessage(), Toast.LENGTH_LONG)
                    .show();
        }

        if (!cameraConfigured) {
            Camera.Parameters parameters = camera.getParameters();
            Camera.Size size = getBestPreviewSize(width, height, parameters);

            if (size != null) {
                parameters.setPreviewSize(size.width, size.height);
                camera.setParameters(parameters);
                cameraConfigured = true;
            }
        }
    }
}

private void startPreview() {
    if (cameraConfigured && camera != null) {
        camera.startPreview();
        inPreview = true;
    }
}

private Camera.Size getBestPreviewSize(int width, int height,
        Camera.Parameters parameters) {
    Camera.Size result = null;

    for (Camera.Size size : parameters.getSupportedPreviewSizes()) {
        if (size.width <= width && size.height <= height) {
            if (result == null) {
                result = size;
            } else {
                int resultArea = result.width * result.height;
                int newArea = size.width * size.height;

                if (newArea > resultArea) {
                    result = size;
                }
            }
        }
    }

    return (result);
}
}