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POStrange behaviour with Camera and SurfaceView
 

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  1. POStrange behaviour with Camera and SurfaceView
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    <p>I'm going crazy with the use of SurfaceView.</p> <p>I've developed an app which takes pictures at fixed time intervals. It works well with my device with Androd 2.3. Here is a sample code:</p> <pre><code>public class MainActivity extends Activity { private Camera mCamera; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); Button captureButton = (Button) findViewById(R.id.button_capture); captureButton.setOnClickListener( new View.OnClickListener() { @Override public void onClick(View v) { takeAPicture(); } } ); } private PictureCallback mPicture = new PictureCallback() { @Override public void onPictureTaken(byte[] data, Camera camera) { // ... save image ... camera.release(); camera = null; } }; private void takeAPicture() { mCamera = getCameraInstance(); mCamera.takePicture(null, null, mPicture); } } </code></pre> <p>The same code does not work with Android 4.1. Googling a bit I've found that "most of the modern Android devices now check that a SurfaceView exists and has a non-zero width and height". So I've modified the above code as follows:</p> <pre><code>public class MainActivity extends Activity { private Camera mCamera; private CameraPreview mPreview; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); Button captureButton = (Button) findViewById(R.id.button_capture); captureButton.setOnClickListener( new View.OnClickListener() { @Override public void onClick(View v) { takeAPicture(); } } ); } @Override public boolean onCreateOptionsMenu(Menu menu) { // Inflate the menu; this adds items to the action bar if it is present. getMenuInflater().inflate(R.menu.main, menu); return true; } private PictureCallback mPicture = new PictureCallback() { @Override public void onPictureTaken(byte[] data, Camera camera) { // ... save image ... camera.release(); camera = null; } }; private void takeAPicture() { mCamera = getCameraInstance(); mPreview = new CameraPreview(this, mCamera); FrameLayout preview = (FrameLayout) findViewById(R.id.camera_preview); preview.addView(mPreview); mCamera.takePicture(null, null, mPicture); } } </code></pre> <p>where CameraPreview is:</p> <pre><code>public class CameraPreview extends SurfaceView implements SurfaceHolder.Callback { private SurfaceHolder mHolder; private Camera mCamera; public CameraPreview(Context context, Camera camera) { super(context); mCamera = camera; // 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); mCamera.startPreview(); } catch (IOException e) { Log.d(MainActivity.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 // start preview with new settings try { mCamera.setPreviewDisplay(mHolder); mCamera.startPreview(); } catch (Exception e){ Log.d(MainActivity.TAG, "Error starting camera preview: " + e.getMessage()); } } } </code></pre> <p>But the PictureCallback is not invoked and the user interface of the app disappear. The user interface is simply a FrameLayout and a button as follows:</p> <pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt; &lt;LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:orientation="vertical" android:layout_width="fill_parent" android:layout_height="fill_parent"&gt; &lt;FrameLayout android:id="@+id/camera_preview" android:layout_width="100dp" android:layout_height="100dp" /&gt; &lt;Button android:id="@+id/button_capture" android:text="Capture" android:layout_width="wrap_content" android:layout_height="wrap_content" /&gt; &lt;/LinearLayout&gt; </code></pre> <p>What's wrong?</p> <p>Please note that if I do:</p> <pre><code>public class MainActivity extends Activity { private Camera mCamera; private CameraPreview mPreview; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); mCamera = getCameraInstance(); mPreview = new CameraPreview(this, mCamera); FrameLayout preview = (FrameLayout) findViewById(R.id.camera_preview); preview.addView(mPreview); Button captureButton = (Button) findViewById(R.id.button_capture); captureButton.setOnClickListener( new View.OnClickListener() { @Override public void onClick(View v) { mCamera.takePicture(null, null, mPicture); } } ); } </code></pre> <p>of course removing the mCamera.release() from the PictureCallback, it works perfectly on a device with Android 4.1. Any comment? </p>
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