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.
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.
On this 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.
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?
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 <= width && size.height <= height) {
if (result == null) {
result=size;
}
else {
int resultArea = result.width * result.height;
int newArea = size.width * size.height;
if (newArea > 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<byte[], String, String> {
@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);
}
}
}
Update
As for the exceptions I was getting, if I tried making the main function like the code below,
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);
}
}
I get "The application has stopped unexpectedly. Please Try again." I was basically trying to follow the steps that the android documention specifies. I also tried putting this code into the onResume function after the camera object is retrieved, and then calling this.onResume.
