android camera preview blank screen
- by user1104836
I want to capture a photo manually not by using existing camera apps. So i made this Activity:
public class CameraActivity extends Activity {
private Camera mCamera;
private Preview mPreview;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_camera);
// Create an instance of Camera
// mCamera = Camera.open(0);
// Create our Preview view and set it as the content of our activity.
mPreview = new Preview(this);
mPreview.safeCameraOpen(0);
FrameLayout preview = (FrameLayout) findViewById(R.id.camera_preview);
preview.addView(mPreview);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.activity_camera, menu);
return true;
}
}
This is the CameraPreview which i want to use:
public class Preview extends ViewGroup implements SurfaceHolder.Callback {
SurfaceView mSurfaceView;
SurfaceHolder mHolder;
//CAM INSTANCE ================================
private Camera mCamera;
List<Size> mSupportedPreviewSizes;
//=============================================
/**
* @param context
*/
public Preview(Context context) {
super(context);
mSurfaceView = new SurfaceView(context);
addView(mSurfaceView);
// Install a SurfaceHolder.Callback so we get notified when the
// underlying surface is created and destroyed.
mHolder = mSurfaceView.getHolder();
mHolder.addCallback(this);
mHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
}
/**
* @param context
* @param attrs
*/
public Preview(Context context, AttributeSet attrs) {
super(context, attrs);
// TODO Auto-generated constructor stub
}
/**
* @param context
* @param attrs
* @param defStyle
*/
public Preview(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
// TODO Auto-generated constructor stub
}
/* (non-Javadoc)
* @see android.view.ViewGroup#onLayout(boolean, int, int, int, int)
*/
@Override
protected void onLayout(boolean arg0, int arg1, int arg2, int arg3, int arg4) {
// TODO Auto-generated method stub
}
@Override
public void surfaceChanged(SurfaceHolder holder, int format, int width,
int height) {
// Now that the size is known, set up the camera parameters and begin
// the preview.
Camera.Parameters parameters = mCamera.getParameters();
parameters.setPreviewSize(width, height);
requestLayout();
mCamera.setParameters(parameters);
/*
Important: Call startPreview() to start updating the preview surface. Preview must be
started before you can take a picture.
*/
mCamera.startPreview();
}
@Override
public void surfaceCreated(SurfaceHolder holder) {
// TODO Auto-generated method stub
}
@Override
public void surfaceDestroyed(SurfaceHolder holder) {
// Surface will be destroyed when we return, so stop the preview.
if (mCamera != null) {
/*
Call stopPreview() to stop updating the preview surface.
*/
mCamera.stopPreview();
}
}
/**
* When this function returns, mCamera will be null.
*/
private void stopPreviewAndFreeCamera() {
if (mCamera != null) {
/*
Call stopPreview() to stop updating the preview surface.
*/
mCamera.stopPreview();
/*
Important: Call release() to release the camera for use by other applications.
Applications should release the camera immediately in onPause() (and re-open() it in
onResume()).
*/
mCamera.release();
mCamera = null;
}
}
public void setCamera(Camera camera) {
if (mCamera == camera) { return; }
stopPreviewAndFreeCamera();
mCamera = camera;
if (mCamera != null) {
List<Size> localSizes = mCamera.getParameters().getSupportedPreviewSizes();
mSupportedPreviewSizes = localSizes;
requestLayout();
try {
mCamera.setPreviewDisplay(mHolder);
} catch (IOException e) {
e.printStackTrace();
}
/*
Important: Call startPreview() to start updating the preview surface. Preview must
be started before you can take a picture.
*/
mCamera.startPreview();
}
}
public boolean safeCameraOpen(int id) {
boolean qOpened = false;
try {
releaseCameraAndPreview();
mCamera = Camera.open(id);
mCamera.startPreview();
qOpened = (mCamera != null);
} catch (Exception e) {
// Log.e(R.string.app_name, "failed to open Camera");
e.printStackTrace();
}
return qOpened;
}
Camera.PictureCallback mPicCallback = new Camera.PictureCallback() {
@Override
public void onPictureTaken(byte[] data, Camera camera) {
// TODO Auto-generated method stub
Log.d("lala", "pic is taken");
}
};
public void takePic() {
mCamera.startPreview();
// mCamera.takePicture(null, mPicCallback, mPicCallback);
}
private void releaseCameraAndPreview() {
this.setCamera(null);
if (mCamera != null) {
mCamera.release();
mCamera = null;
}
}
}
This is the Layout of CameraActivity:
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".CameraActivity" >
<FrameLayout
android:id="@+id/camera_preview"
android:layout_width="0dip"
android:layout_height="fill_parent"
android:layout_weight="1"
/>
<Button
android:id="@+id/button_capture"
android:text="Capture"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
/>
</LinearLayout>
But when i start the CameraActivity, i just see a blank white background and the Capture-Button??? Why i dont see the Camera-Screen?
