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POandroid camera preview blank screen
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copied!<p>I want to capture a photo manually not by using existing camera apps. So i made this <strong>Activity</strong>:</p> <pre><code> 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); if(mCamera !=null) Log.i("CameraActivity.onCreate()", "mCamera initialized"); // Create our Preview view and set it as the content of our activity. mPreview = new Preview(this); if(mPreview !=null) Log.i("CameraActivity.onCreate()", "mPreview initialized"); FrameLayout preview = (FrameLayout) findViewById(R.id.camera_preview); preview.addView(mPreview); Log.i("CameraActivity.onCreate()", "mPreview added to FrameLayout"); mPreview.setCamera(mCamera); Log.i("CameraActivity.onCreate()", "mPreview.setCamera(mCamera)"); } @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; } @Override public void onPause() { super.onPause(); mPreview.stopPreviewAndFreeCamera(); } } </code></pre> <p>This is the CameraPreview which i want to use:</p> <pre><code> public class Preview extends ViewGroup implements SurfaceHolder.Callback { SurfaceView mSurfaceView; SurfaceHolder mHolder; private Camera mCamera; List<Size> mSupportedPreviewSizes; /** * @param context */ public Preview(Context context) { super(context); mSurfaceView = new SurfaceView(context); Log.i("CameraPreview.constructor(...)", "mSurfaceView initialized"); if(mSurfaceView==null) {Log.i("CameraPreview.constructor(...)", "mSurfaceView is null");} addView(mSurfaceView); // Install a SurfaceHolder.Callback so we get notified when the // underlying surface is created and destroyed. mHolder = mSurfaceView.getHolder(); Log.i("CameraPreview.constructor(...)", "mHolder setup"); if(mHolder==null) {Log.e("PreviewCamera", "mHolder is null");} 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(); Log.i("CameraPreview.surfaceChanged(...)", "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(); Log.i("CameraPreview.surfaceDestroyed(...)", "mCamera.stopPreview()"); } } /** * When this function returns, mCamera will be null. */ public void stopPreviewAndFreeCamera() { if (mCamera != null) { /* Call stopPreview() to stop updating the preview surface. */ mCamera.stopPreview(); Log.i("CameraPreview.stopPreviewAndFreeCamera()", "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(); Log.i("CameraPreview.stopPreviewAndFreeCamera()", "mCamera.release()"); mCamera = null; } } /*** * * @param camera */ public void setCamera(Camera camera) { if (mCamera == camera) { Log.i("CameraPreview.setCamera()", "mCamera equals the Camera you want to set"); return; } stopPreviewAndFreeCamera(); Log.i("CameraPreview.setCamera()", "stopPreviewAndFreeCamera()"); mCamera = camera; Log.i("CameraPreview.setCamera()", "setup new Camera"); if (mCamera != null) { List<Size> localSizes = mCamera.getParameters().getSupportedPreviewSizes(); mSupportedPreviewSizes = localSizes; requestLayout(); try { mCamera.setPreviewDisplay(mHolder); Log.i("CameraPreview.setCamera()", "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(); Log.i("CameraPreview.setCamera()", "mCamera.startPreview()"); } } /*** * * @param id * @return */ public boolean safeCameraOpen(int id) { boolean qOpened = false; try { releaseCameraAndPreview(); mCamera = Camera.open(id); 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.takePicture(null, mPicCallback, mPicCallback); } /** * */ private void releaseCameraAndPreview() { this.setCamera(null); if (mCamera != null) { mCamera.release(); mCamera = null; } } } </code></pre> <p>This is the Layout of CameraActivity:</p> <pre><code><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> </code></pre> <p><strong>But when i start the CameraActivity, i just see a blank white background and the Capture-Button??? Why i dont see the Camera-Screen?</strong></p> <p>EDIT: Logcat:</p> <pre><code>12-16 13:09:39.941: I/CameraActivity.onCreate()(439): mCamera initialized 12-16 13:09:39.941: I/CameraPreview.constructor(...)(439): mSurfaceView initialized 12-16 13:09:39.941: I/CameraPreview.constructor(...)(439): mHolder setup 12-16 13:09:39.941: I/CameraActivity.onCreate()(439): mPreview initialized 12-16 13:09:39.952: I/CameraActivity.onCreate()(439): mPreview added to FrameLayout 12-16 13:09:39.952: I/CameraPreview.setCamera()(439): stopPreviewAndFreeCamera() 12-16 13:09:39.952: I/CameraPreview.setCamera()(439): setup new Camera 12-16 13:09:39.961: D/Camera(439): app passed NULL surface 12-16 13:09:39.961: I/CameraPreview.setCamera()(439): mCamera.setPreviewDisplay(mHolder) 12-16 13:09:39.971: I/CameraPreview.setCamera()(439): mCamera.startPreview() 12-16 13:09:39.971: I/CameraActivity.onCreate()(439): mPreview.setCamera(mCamera) 12-16 13:09:40.622: I/ActivityManager(60): Displayed com.example.popup/.CameraActivity: +810ms </code></pre>

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