Android Camera预览未显示

Question

I found a tutorial online here both for capturing images, they are very similar and I used one another to figure out why my Camera code isn't working.

I do not get any syntax errors in Android but when I go on the desired fragment it is just a white screen, there is no camera display and I have no idea why I have looked at both code examples in depth and googled my problem but cant find anything. The only difference with my code is that its a fragment instead of an activity. Can someone please help me?

Here is my code:

public class Image extends Fragment implements SurfaceHolder.Callback {

private ImageView imageView;
private SurfaceView mSurfaceView;
private Bitmap capturedImage;


//Camera

private SurfaceHolder sHolder;
private Camera mCamera;
private Parameters parameters;

/**********************************************/

public Image() {
    // Required empty public constructor
}

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

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
    View view = inflater.inflate(R.layout.image_activity, container, false);

    imageView = (ImageView) view.findViewById(R.id.imageView);
    mSurfaceView = (SurfaceView) view.findViewById(R.id.surfaceView);

    //Get a surface
    sHolder = mSurfaceView.getHolder();

    //add the callback interface methods defined below as the Surface View callbacks
    sHolder.addCallback(this);

    //tells Android that this surface will have its data constantly replaced
    sHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);

    return view;
}

@Override
public void surfaceCreated(SurfaceHolder holder) {

    // The Surface has been created, acquire the camera and tell it where
    // to draw the preview.

    mCamera = Camera.open();
    try {
        mCamera.setPreviewDisplay(holder);

    } catch (IOException exception) {
        mCamera.release();
        mCamera = null;
    }
}

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


    //get camera parameters
    parameters = mCamera.getParameters();

    parameters.setPreviewSize(352, 288);
    //set camera parameters
    mCamera.setParameters(parameters);
    mCamera.startPreview();

    //sets what code should be executed after the picture is taken
    Camera.PictureCallback mCall = new Camera.PictureCallback() {
        @Override
        public void onPictureTaken(byte[] data, Camera camera) {
            //decode the data obtained by the camera into a Bitmap
            capturedImage = BitmapFactory.decodeByteArray(data, 0, data.length);
            String filename= Environment.getExternalStorageDirectory()
                    + File.separator + "testimage.jpg";
            FileOutputStream out = null;
            try {
                out = new FileOutputStream(filename);
                capturedImage.compress(Bitmap.CompressFormat.PNG, 100, out); // bmp is your Bitmap instance
                // PNG is a lossless format, the compression factor (100) is ignored
            } catch (Exception e) {
                e.printStackTrace();
            } finally {
                try {
                    if (out != null) {
                        out.close();
                    }
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            //set the iv_image
            imageView.setImageBitmap(capturedImage);
        }
    };

    mCamera.takePicture(null, null, mCall);

}

@Override
public void surfaceDestroyed(SurfaceHolder holder) {

    mCamera.stopPreview();
    mCamera.release();
    mCamera = null;
  }
}

Here is my XML file:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent">

<SurfaceView
    android:id="@+id/surfaceView"
    android:layout_height="0dip"
    android:layout_width="0dip">

</SurfaceView>

<ImageView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:id="@+id/imageView">

</ImageView>

</LinearLayout>

Update 1:

Here is my manifest file, I forgot to include this:

<uses-permission android:name="android.permission.CAMERA"/>
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-feature android:name="android.hardware.camera" />
<uses-feature android:name="android.hardware.camera.autofocus" />

I have also enabled the permissions in marshmallow settings for the application but still doesn't show anything

Update 2: Just tried it with a API 17 device and there is still no preview

Answer 1

请确保已将必需的相机权限添加到AndroidManifest.xml文件中；如果您使用的是蛋白软糖，请再检查一步，从设置=>应用程序=>应用程序管理器=>您的应用程序=>权限中启用权限

Answer 2

Assuming all your code is actually running as you expect, one possibility: setPreviewSize(352, 288) - that size may not be supported.

You'll need to check the list of supported preview sizes and pick one, or use 320,240 or 640,480 which are basically always available.

Answer 3

在XML中，android_height和android_width为0，将其更改！