我正在开发这个需要访问相机的应用程序。我已经很好地访问了它。但是有两个问题。 当手机垂直时，预览全部拉伸。其次，当我恢复应用程序时，相机预览不可见。 camera.open（）函数会打开相机，但我无法看到预览。我已经尝试了论坛上提供的所有帮助，但实际上并没有解决我的问题。
- 提前谢谢！
//Camera Activity file
@SuppressLint("SimpleDateFormat")
public class CameraActivity extends Activity {
private Camera mCamera;
private CameraPreview mPreview;
private FrameLayout preview;
private Button bCapture;
private Button bGallery;
private static final String TAG = "CameraActivity";
private static final int PICK_IMAGE_REQUEST = 1;
private TextView tvCheck;
public final static String EXTRA_MESSAGE = "com.epfl.mycamera.MESSAGE";
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
getWindow().requestFeature(Window.FEATURE_NO_TITLE);
getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);
setContentView(R.layout.activity_camera);
if (checkCameraHardware(getBaseContext())){
// Create an instance of Camera
mCamera = getCameraInstance();
// Create our Preview view and set it as the content of our activity.
mPreview = new CameraPreview(this, mCamera, CameraActivity.this);
preview = (FrameLayout) findViewById(R.id.camera_preview);
preview.addView(mPreview);
//Adding Camera Button
bCapture = (Button) findViewById(R.id.bCapture);
//Button Listener for storing images
bCapture.setOnClickListener( new View.OnClickListener() {
@Override
public void onClick(View v) {
mCamera.takePicture(null, null, null, jpegCallback);
mCamera.startPreview();
Log.d(TAG, "takePicture");
}
});
//Adding Gallery Button
bGallery = (Button) findViewById (R.id.bGallery);
bGallery.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
tvCheck = (TextView) findViewById (R.id.tvCheck);
selectImageFromGallery();
}
});
}
Log.d(TAG, "OnCreate");
}
/******************************************************************/
public void selectImageFromGallery() {
Intent intent = new Intent();
intent.setType("image/*");
intent.setAction(Intent.ACTION_GET_CONTENT);
startActivityForResult(Intent.createChooser(intent, "Select Picture"),PICK_IMAGE_REQUEST);
}
@Override
protected void onActivityResult(int aRequestCode, int aResultCode, Intent aData) {
switch (aRequestCode) {
case PICK_IMAGE_REQUEST:
handleImage(aData);
break;
default:
tvCheck.setText("You can only select images.");
break;
}
super.onActivityResult(aRequestCode, aResultCode, aData);
}
private void handleImage(Intent aData) {
if ((aData != null) && (aData.getData() != null)) {
Uri selectedImage = aData.getData();
String[] filePathColumn = {MediaColumns.DATA};
Cursor cursor = getContentResolver().query(selectedImage, filePathColumn, null, null, null);
cursor.moveToFirst();
Log.d("ImageActivity", "After extracting file Path");
int columnIndex = cursor.getColumnIndex(filePathColumn[0]);
String picturePath = cursor.getString(columnIndex);
cursor.close();
Log.d("ImageActivity", "After closing the cursor");
setContentView(R.layout.activity_image_old); //setting the view to the image
ImageView imgView = (ImageView) findViewById(R.id.ivGallery);
imgView.setImageBitmap(BitmapFactory.decodeFile(picturePath));
Button bLiveCamera = (Button) findViewById(R.id.bCameraPreview);
bLiveCamera.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
setContentView(R.layout.activity_camera);
mCamera.startPreview();
}
});
}
else {
tvCheck.setText("You did not select an image");
}
}
/****************************************************************/
/** Stores jpeg picture */
PictureCallback jpegCallback = new PictureCallback() {
public void onPictureTaken(byte[] data, Camera camera) {
try {
File mediaStorageDir = new File(Environment .getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES),"MyCamera");
// Saving image to the SD CARD with a file operation
String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss").format(new Date());
File mediaFile;
mediaFile = new File(mediaStorageDir.getPath() + File.separator +"IMG_"+ timeStamp + ".jpg");
FileOutputStream outStream = new FileOutputStream(mediaFile);
outStream.write(data);
outStream.close();
sendBroadcast(new Intent(Intent.ACTION_MEDIA_MOUNTED, Uri.parse("file://"+ Environment.getExternalStorageDirectory())));
Log.d(TAG, "onPictureTaken - wrote bytes: " + data.length);
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} finally {
} Log.d(TAG, "onPictureTaken - jpeg");
}
};
/***************************************************************/
/** Check if this device has a camera */
private boolean checkCameraHardware(Context context) {
if (context.getPackageManager().hasSystemFeature(PackageManager.FEATURE_CAMERA)){
Log.d(TAG, "Camera Available");
return true;
} else {
Log.d(TAG, "No Camera Found");
return false;
}
}
/** A safe way to get an instance of the Camera object. */
public Camera getCameraInstance(){
Camera c = null;
try {
int i = Camera.getNumberOfCameras();
releaseCamera(); //in case camera is being accessed by any other app.
Log.d(TAG, "Number of Cameras "+i +"\n");
c = Camera.open(); // attempt to get a Camera instance
Log.d(TAG, "Camera Opened");
}
catch (Exception e){
Log.d(TAG, "Camera Can't Be Accessed");
}
return c; // returns null if camera is unavailable
}
@Override
protected void onPause() {
super.onPause();
releaseCamera(); // release the camera immediately on pause event
}
private void releaseCamera(){
if (mCamera != null){
mPreview.getHolder().removeCallback(mPreview);
mCamera.release(); // release the camera for other applications
}
}
@Override
public void onResume() {
super.onResume();
// Get the Camera instance as the activity achieves full user focus
if (mCamera == null) {
getCameraInstance();
mCamera.startPreview();
}
}
}
这是我的相机预览课程：
@SuppressLint({ "ViewConstructor", "SdCardPath" })
public class CameraPreview extends SurfaceView implements SurfaceHolder.Callback {
private static final String TAG = "CameraPreview";
private SurfaceHolder mHolder;
private Camera mCamera;
private Size mPreviewSize;
// private Activity CameraActivity;
@SuppressWarnings("deprecation")
public CameraPreview(Context context, Camera camera, Activity activity) {
super(context);
mCamera = camera;
//CameraActivity = activity;
// Install a SurfaceHolder.Callback so we get notified when the
// underlying surface is created and destroyed.
mHolder = getHolder();
mHolder.addCallback(this);
mHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
}
public void surfaceCreated(SurfaceHolder holder) {
// The Surface has been created, now tell the camera where to draw the preview.
try {
mCamera.setPreviewDisplay(holder);
//add camera preview call back here.
mCamera.startPreview();
} catch (IOException e) {
Log.d(TAG, "Error setting camera preview: " + e.getMessage());
}
}
public void surfaceDestroyed(SurfaceHolder holder) {
// empty. Take care of releasing the Camera preview in your activity.
}
public void surfaceChanged(SurfaceHolder holder, int format, int w, int h) {
// If your preview can change or rotate, take care of those events here.
// Make sure to stop the preview before resizing or reformatting it.
if (mHolder.getSurface() == null){
// preview surface does not exist
return;
}
// stop preview before making changes
try{
mCamera.stopPreview();
} catch (Exception e){
// ignore: tried to stop a non-existent preview
}
// set preview size and make any resize, rotate or
// reformatting changes here
Camera.Parameters parameters = mCamera.getParameters();
List<Size> localSizes = mCamera.getParameters().getSupportedPreviewSizes();
mPreviewSize = localSizes.get(0);
Log.d(TAG, "Width " + mPreviewSize.width);
Log.d(TAG, "Height " + mPreviewSize.height);
parameters.setPreviewSize(mPreviewSize.width, mPreviewSize.height );
mHolder.setFixedSize(mPreviewSize.width, mPreviewSize.height);
requestLayout();
mCamera.setParameters(parameters);
//start preview with new settings
try {
mCamera.setPreviewDisplay(mHolder);
mCamera.setDisplayOrientation(90);
//setCameraDisplayOrientation(CameraActivity, 0, mCamera);
mCamera.startPreview();
} catch (Exception e){
Log.d(TAG, "Error starting camera preview: " + e.getMessage());
}
}
}
答案 0 :(得分：3)
您只能在Activity的onCreate（）上创建一个CameraPreview。但是相机实例在onPause（）上释放，并且在onResume（）上打开一个新实例。因此，您需要再次设置曲面。