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POHow do you get a simple camera program working for Android?
 

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  1. POHow do you get a simple camera program working for Android?
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    <p>I just started programming in Java, and I need to get a simple application up that shows the camera, takes a picture, and sends that picture data somewhere.</p> <p>I have been searching all over the web trying to find a good camera tutorial that worked as expected, but apparently they all require some inner knowledge that I do not have yet.</p> <p>On <a href="https://stackoverflow.com/questions/2713165/take-and-save-picture-on-button-press">this</a> page, commonsWare pointed to code that had some sample code in it for using the camera. I have taken the PictureDemo code and got it running with no errors. However, it only brings up a black screen. I assume this is because the program is not actually activating the preview, or camera in the main function, but every time I try adding the code I think I need, I am getting exceptions.</p> <p>So my question is, what do I need to add in the main function to get the camera going? Or is there a better tutorial somewhere that I can see simple basic code for getting the camera up?</p> <pre><code>package assist.core; import android.app.Activity; import android.graphics.PixelFormat; import android.hardware.Camera; import android.os.AsyncTask; import android.os.Bundle; import android.os.Environment; import android.util.Log; import android.view.KeyEvent; import android.view.SurfaceHolder; import android.view.SurfaceView; import android.widget.Toast; import java.io.File; import java.io.FileOutputStream; import java.io.IOException; import java.util.logging.Level; import java.util.logging.Logger; public class MainActivity extends Activity { private SurfaceView preview = null; private SurfaceHolder previewHolder = null; private Camera camera = null; private boolean inPreview = false; /** * */ @Override public void onCreate(Bundle savedInstanceState) { //Call the parent class super.onCreate(savedInstanceState); setContentView(R.layout.main); preview = (SurfaceView) findViewById(R.id.preview); previewHolder = preview.getHolder(); previewHolder.addCallback(surfaceCallback); previewHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS); } @Override public void onResume() { super.onResume(); //Get the camera instance camera = CameraFinder.INSTANCE.open(); } @Override public void onPause() { if (inPreview) { camera.stopPreview(); } camera.release(); camera = null; inPreview = false; super.onPause(); } @Override public boolean onKeyDown(int keyCode, KeyEvent event) { if (keyCode == KeyEvent.KEYCODE_CAMERA || keyCode == KeyEvent.KEYCODE_SEARCH) { if (inPreview) { camera.takePicture(null, null, photoCallback); inPreview = false; } return(true); } return(super.onKeyDown(keyCode, event)); } private Camera.Size getBestPreviewSize(int width, int height, Camera.Parameters parameters) { Camera.Size result = null; for (Camera.Size size : parameters.getSupportedPreviewSizes()) { if (size.width &lt;= width &amp;&amp; size.height &lt;= height) { if (result == null) { result=size; } else { int resultArea = result.width * result.height; int newArea = size.width * size.height; if (newArea &gt; resultArea) { result = size; } } } } return(result); } SurfaceHolder.Callback surfaceCallback = new SurfaceHolder.Callback() { public void surfaceCreated(SurfaceHolder holder) { try { camera.setPreviewDisplay(previewHolder); } catch (Throwable t) { Log.e("MainActivity-surfaceCallback", "Exception in setPreviewDisplay()", t); Toast.makeText(MainActivity.this, t.getMessage(), Toast.LENGTH_LONG).show(); } } public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) { Camera.Parameters parameters = camera.getParameters(); Camera.Size size = getBestPreviewSize(width, height, parameters); if (size != null) { parameters.setPreviewSize(size.width, size.height); parameters.setPictureFormat(PixelFormat.JPEG); camera.setParameters(parameters); camera.startPreview(); inPreview = true; } } public void surfaceDestroyed(SurfaceHolder holder) { // no-op } }; Camera.PictureCallback photoCallback = new Camera.PictureCallback() { public void onPictureTaken(byte[] data, Camera camera) { new SavePhotoTask().execute(data); camera.startPreview(); inPreview = true; } }; class SavePhotoTask extends AsyncTask&lt;byte[], String, String&gt; { @Override protected String doInBackground(byte[]... jpeg) { File photo = new File(Environment.getExternalStorageDirectory(), "photo.jpg"); if(photo.exists()) { photo.delete(); } try { FileOutputStream fos = new FileOutputStream(photo.getPath()); fos.write(jpeg[0]); fos.close(); } catch (java.io.IOException e) { Log.e("MainActivity", "Exception in photoCallback", e); } return(null); } } } </code></pre> <p><strong>Update</strong></p> <p>As for the exceptions I was getting, if I tried making the main function like the code below,</p> <pre><code>public void onCreate(Bundle savedInstanceState) { //Call the parent class super.onCreate(savedInstanceState); setContentView(R.layout.main); preview = (SurfaceView) findViewById(R.id.preview); previewHolder = preview.getHolder(); previewHolder.addCallback(surfaceCallback); previewHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS); Camera.Parameters parameters = camera.getParameters(); parameters.setPictureFormat(PixelFormat.JPEG); camera.setParameters(parameters); try { //Start the camera preview display camera.setPreviewDisplay(previewHolder); camera.startPreview(); } catch (IOException ex) { Logger.getLogger(MainActivity.class.getName()).log(Level.SEVERE, null, ex); } } </code></pre> <p>I get "The application has stopped unexpectedly. Please Try again." I was basically trying to follow the steps that the <a href="http://developer.android.com/reference/android/hardware/Camera.html#setPreviewDisplay(android.view.SurfaceHolder)" rel="nofollow noreferrer">android documention</a> specifies. I also tried putting this code into the onResume function after the camera object is retrieved, and then calling this.onResume.</p>
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