我正在使用此条形码阅读器代码，当应用程序进入onPause（）阶段然后返回onResume（）时，它会冻结。当应用程序进入onPause（）阶段时，相机将被释放，这就是它冻结的原因。我尝试在onResume（）中再次初始化相机，但是当首次调用片段时也会调用它，那么如何再次初始化我的相机呢？我还建议使用onPostResume（）但我无法在片段中使用它。你能指导我吗？
这是片段：
public class BarcodeReaderFragment extends Fragment {
private Camera mCamera;
private CameraPreview mPreview;
private Handler autoFocusHandler;
TextView scanText, refreshbarcode;
Button scanButton, homeButton;
ImageScanner scanner;
private boolean barcodeScanned = false;
private boolean previewing = true;
static {
System.loadLibrary("iconv");
}
FragmentManager fragmentManager;
FrameLayout preview;
Typeface font;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
font = Typeface.createFromAsset(getActivity().getAssets(),
"fontello.ttf");
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.barcodereader_fragment,
container, false);
getActivity().setRequestedOrientation(
ActivityInfo.SCREEN_ORIENTATION_PORTRAIT);
((MainActivity) getActivity()).getMenuListView()
.setItemChecked(0, true);
((MainActivity) getActivity()).getMenuListView().setSelection(0);
refreshbarcode = (TextView) view.findViewById(R.id.refreshbarcode);
refreshbarcode.setTypeface(font);
refreshbarcode.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
fragmentManager = getActivity().getSupportFragmentManager();
FragmentTransaction fragmentTransaction = fragmentManager
.beginTransaction();
fragmentTransaction.replace(R.id.frame_container,
new BarcodeReaderFragment());
fragmentTransaction.commit();
}
});
homeButton = (Button) view.findViewById(R.id.homebutton);
homeButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
fragmentManager = getActivity().getSupportFragmentManager();
FragmentTransaction fragmentTransaction = fragmentManager
.beginTransaction();
fragmentTransaction.replace(R.id.frame_container,
HomeFragment.newInstance());
fragmentTransaction.commit();
}
});
autoFocusHandler = new Handler();
mCamera = getCameraInstance();
/* Instance barcode scanner */
scanner = new ImageScanner();
scanner.setConfig(0, Config.X_DENSITY, 3);
scanner.setConfig(0, Config.Y_DENSITY, 3);
mPreview = new CameraPreview(getActivity(), mCamera, previewCb,
autoFocusCB);
preview = (FrameLayout) view.findViewById(R.id.cameraPreview);
preview.addView(mPreview);
scanText = (TextView) view.findViewById(R.id.scanText);
fragmentManager = getActivity().getSupportFragmentManager();
return view;
}
@Override
public void onPause() {
super.onPause();
releaseCamera();
}
@Override
public void onResume() {
Log.i("DEBUG", "onResume of HomeFragment");
getActivity().setRequestedOrientation(
ActivityInfo.SCREEN_ORIENTATION_PORTRAIT);
autoFocusHandler = new Handler();
mCamera = getCameraInstance();
/* Instance barcode scanner */
scanner = new ImageScanner();
scanner.setConfig(0, Config.X_DENSITY, 3);
scanner.setConfig(0, Config.Y_DENSITY, 3);
mPreview = new CameraPreview(getActivity(), mCamera, previewCb,
autoFocusCB);
preview.removeAllViews();
preview.addView(mPreview);
super.onResume();
}
/** A safe way to get an instance of the Camera object. */
public static Camera getCameraInstance() {
Camera c = null;
try {
c = Camera.open();
} catch (Exception e) {
}
return c;
}
private void releaseCamera() {
if (mCamera != null) {
previewing = false;
mCamera.setPreviewCallback(null);
mCamera.release();
mCamera = null;
}
}
private Runnable doAutoFocus = new Runnable() {
public void run() {
if (previewing)
mCamera.autoFocus(autoFocusCB);
}
};
PreviewCallback previewCb = new PreviewCallback() {
public void onPreviewFrame(byte[] data, Camera camera) {
Camera.Parameters parameters = camera.getParameters();
Size size = parameters.getPreviewSize();
Image barcode = new Image(size.width, size.height, "Y800");
barcode.setData(data);
int result = scanner.scanImage(barcode);
if (result != 0) {
SymbolSet syms = scanner.getResults();
for (Symbol sym : syms) {
scanText.setText("Barkod Sonucu: " + sym.getData());
scanText.setTextColor(Color.parseColor("#00AF03"));
barcodeScanned = true;
releaseCamera();
Intent intent = new Intent();
intent.putExtra("SCAN_RESULT", sym.getData());
getActivity().setResult(getActivity().RESULT_OK, intent);
}
}
}
};
// Mimic continuous auto-focusing
AutoFocusCallback autoFocusCB = new AutoFocusCallback() {
public void onAutoFocus(boolean success, Camera camera) {
autoFocusHandler.postDelayed(doAutoFocus, 1000);
}
};
}
CameraPreview代码：
/*
* Barebones implementation of displaying camera preview.
*
* Created by lisah0 on 2012-02-24
*/
/** A basic Camera preview class */
public class CameraPreview extends SurfaceView implements SurfaceHolder.Callback {
private SurfaceHolder mHolder;
private Camera mCamera;
private PreviewCallback previewCallback;
private AutoFocusCallback autoFocusCallback;
public CameraPreview(Context context, Camera camera,
PreviewCallback previewCb,
AutoFocusCallback autoFocusCb) {
super(context);
mCamera = camera;
previewCallback = previewCb;
autoFocusCallback = autoFocusCb;
/*
* Set camera to continuous focus if supported, otherwise use
* software auto-focus. Only works for API level >=9.
*/
Camera.Parameters parameters = camera.getParameters();
for (String f : parameters.getSupportedFocusModes()) {
if (f == Parameters.FOCUS_MODE_CONTINUOUS_PICTURE) {
mCamera.autoFocus(autoFocusCb);
//mCamera.setFocusMode(Parameters.FOCUS_MODE_CONTINUOUS_PICTURE);
autoFocusCallback = null;
break;
}
}
// Install a SurfaceHolder.Callback so we get notified when the
// underlying surface is created and destroyed.
mHolder = getHolder();
mHolder.addCallback(this);
// deprecated setting, but required on Android versions prior to 3.0
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);
} catch (IOException e) {
Log.d("DBG", "Error setting camera preview: " + e.getMessage());
}
}
public void surfaceDestroyed(SurfaceHolder holder) {
// Camera preview released in activity
}
public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
/*
* 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
}
try {
if(getResources().getConfiguration().orientation == Configuration.ORIENTATION_PORTRAIT) {
mCamera.setDisplayOrientation(90);
}
else if(getResources().getConfiguration().orientation == Configuration.ORIENTATION_LANDSCAPE) {
mCamera.setDisplayOrientation(0);
}
mCamera.setPreviewDisplay(mHolder);
mCamera.setPreviewCallback(previewCallback);
mCamera.startPreview();
mCamera.autoFocus(autoFocusCallback);
} catch (Exception e){
Log.d("DBG", "Error starting camera preview: " + e.getMessage());
}
}
}
答案 0 :(得分：1)
您可以从onCreateView中删除与相机相关的代码。 onResume就足够了。
答案 1 :(得分：0)
如果在onPause()期间发布了相机资源，则需要使用onResume()方法在reconnect()中回收这些资源。在onResume()之后，您需要拨打mCamera.reconnect()，否则您的物理相机资源将不会绑定到您的相机对象。