Develop Reference

White screen on activity start

I'm not sure whether I'm understanding this properly but according to the life cycle of an activity onCreate is run first. As such, I've attempted to continue to run the activity from there by calling the onStart method.
Not sure whether that is even the correct thing to do. Regardless, the moment I start the activity (through a button in the main) all I see is a white screen. I've got setContentView but it doesn't appear that onCreate is even being run.
I also have the activity included in the manifest correctly and I'm sure of that.
Still new to all this and really unsure what to do though and would like some advice on the proper method of operating the activities methods. This community is fantastic and has helped me a lot in the past so thank you.
package example.myapplication;
import android.app.Activity;
import android.content.Context;
import android.hardware.Camera;
import android.net.Uri;
import android.os.Bundle;
import android.os.Environment;
import android.util.Log;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.View;
import android.widget.Button;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.text.SimpleDateFormat;
import java.util.Date;
/** A basic Camera preview class */
public class CameraPreview extends Activity implements SurfaceHolder.Callback{
private android.hardware.Camera.PictureCallback mPicture;
private Camera mCamera;
private CameraPreview mPreview;
private SurfaceHolder mHolder;
private SurfaceHolder holder;
public void setContentView(int activity_camera) {}
public static final int MEDIA_TYPE_IMAGE = 1;
public static final int MEDIA_TYPE_VIDEO = 2;
private static final String TAG = "CameraPreview";
SurfaceView camera_preview;
Button button_capture;
public CameraPreview(){
super();
}
#Override
public void onCreate(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_camera);
button_capture = (Button) findViewById(R.id.button_capture);
camera_preview = (SurfaceView) findViewById(R.id.camera_preview);
onStart();
}
public void onStart(Context context, Camera camera) {
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.setDisplayOrientation(90);
mCamera.setPreviewDisplay(holder);
mCamera.startPreview();
} catch (IOException e) {
Log.d(TAG, "Error setting camera preview: " + e.getMessage());
}
}
public void surfaceDestroyed(SurfaceHolder holder) {
super.onDestroy();
// 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(TAG, "Error starting camera preview: " + e.getMessage());
}
}
public void onPictureTaken(byte[] data, Camera camera) {
File pictureFile = getOutputMediaFile(MEDIA_TYPE_IMAGE);
if (pictureFile == null){
Log.d(TAG, "Error creating media file, check storage permissions: ");
return;
}
try {
FileOutputStream fos = new FileOutputStream(pictureFile);
fos.write(data);
fos.close();
} catch (FileNotFoundException e) {
Log.d(TAG, "File not found: " + e.getMessage());
} catch (IOException e) {
Log.d(TAG, "Error accessing file: " + e.getMessage());
}
}
/** Create a file Uri for saving an image or video */
private static Uri getOutputMediaFileUri(int type){
return Uri.fromFile(getOutputMediaFile(type));
}
/** Create a File for saving an image or video */
private static File getOutputMediaFile(int type){
// To be safe, you should check that the SDCard is mounted
// using Environment.getExternalStorageState() before doing this.
File mediaStorageDir = new File(Environment.getExternalStoragePublicDirectory(
Environment.DIRECTORY_PICTURES), "MyCameraApp");
// This location works best if you want the created images to be shared
// between applications and persist after your app has been uninstalled.
// Create the storage directory if it does not exist
if (! mediaStorageDir.exists()){
if (! mediaStorageDir.mkdirs()){
Log.d("MyCameraApp", "failed to create directory");
return null;
}
}
// Create a media file name
String timeStamp = new SimpleDateFormat("yyyyMMdd_HH:mm:ss").format(new Date());
File mediaFile;
if (type == MEDIA_TYPE_IMAGE){
mediaFile = new File(mediaStorageDir.getPath() + File.separator +
"IMG_"+ timeStamp + ".jpg");
} else if(type == MEDIA_TYPE_VIDEO) {
mediaFile = new File(mediaStorageDir.getPath() + File.separator +
"VID_"+ timeStamp + ".mp4");
} else {
return null;
}
return mediaFile;
}
public void onClick() {
// Add a listener to the Capture button
Button captureButton = (Button) findViewById(R.id.button_capture);
captureButton.setOnClickListener(new View.OnClickListener() {
public void onClick(View arg0){
// get an image from the camera
mCamera.takePicture(null, null, mPicture);
}
});
}
public SurfaceHolder getHolder() {
return holder;
}
public void setHolder(SurfaceHolder holder) {
this.holder = holder;
}
}

No! Lifecycle methods (e.g. onCreate(), onStart(), onResume(), etc) are called by the android system directly, don't ever explicitly call them yourself. Consider the activity lifecycle here to see how the system calls each method.
Furthermore, looking at your code, your own onStart() method isn't being called anywhere. Looking at the method signature:
public void onStart(Context context, Camera camera) {
You've just inadvertently overloaded the default onStart() method provided by android. Which doesn't really cause a problem, until you call the wrong method in your onCreate(), as shown here:
#Override
public void onCreate(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_camera);
button_capture = (Button) findViewById(R.id.button_capture);
camera_preview = (SurfaceView) findViewById(R.id.camera_preview);
onStart(); // <-- That is the activity's onStart, not yours!
}
which means that the whole block:
public void onStart(Context context, Camera camera) {
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);
}
is never getting called.
Either you dump all that code into onCreate() or name the method something different so you don't confuse yourself.

You don't need to call the onStart() method. You just need to consider the onCreate() method. That's where you start your work.
Also you are calling the setContentView() method wrong. You should call it like this:
setContentView(R.layout.activity_camera);
INSIDE your onCreate() method.

Message "Camera has stopped" when using Glass GDK and Android Camera API

I wondered if anyone has tried using the standard Android Camera API (http://developer.android.com/guide/topics/media/camera.html) to control the camera in an app.
I was able to get my app to work using the startActivityForResult() method, but was a bit disappointed in how long it took to get an image back from the file system, so I wanted to try the other route, using the CameraPreview.
I set up some code based on the Android Camera API example, and it builds and runs fine, but after surfaceChanged executes I get a message in the screen "The Camera has stopped."
Later Edit - I moved the camera activity into its own project and now it works but it gets the preview scrambled. But after the pic is taken it shows fine. Here is the layout code:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="horizontal"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
>
<FrameLayout
android:id="#+id/camera_preview"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:layout_weight="1"
/>
</LinearLayout>
And here is the Activity source:
package com.example.cameratest;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.text.SimpleDateFormat;
import java.util.Date;
import com.google.android.glass.touchpad.Gesture;
import com.google.android.glass.touchpad.GestureDetector;
import android.net.Uri;
import android.os.Bundle;
import android.os.Environment;
import android.provider.MediaStore.Files.FileColumns;
import android.app.Activity;
import android.content.Context;
import android.hardware.Camera;
import android.hardware.Camera.PictureCallback;
import android.util.Log;
import android.view.Menu;
import android.view.MotionEvent;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.WindowManager;
import android.widget.FrameLayout;
public class MainActivity extends Activity {
private static final String TAG = MainActivity.class.getSimpleName();
private GestureDetector mGestureDetector;
private Camera mCamera;
private CameraPreview mPreview;
private static boolean gotCamera = false;
private PictureCallback mPicture = new PictureCallback() {
#Override
public void onPictureTaken(byte[] data, Camera camera) {
File pictureFile = getOutputMediaFile(FileColumns.MEDIA_TYPE_IMAGE);
if (pictureFile == null){
Log.d(TAG, "Error creating media file, check storage permissions");
return;
}
try {
FileOutputStream fos = new FileOutputStream(pictureFile);
fos.write(data);
fos.close();
} catch (FileNotFoundException e) {
Log.d(TAG, "File not found: " + e.getMessage());
} catch (IOException e) {
Log.d(TAG, "Error accessing file: " + e.getMessage());
}
}
};
/** Create a file Uri for saving an image or video */
private static Uri getOutputMediaFileUri(int type){
return Uri.fromFile(getOutputMediaFile(type));
}
/** Create a File for saving an image or video */
private static File getOutputMediaFile(int type){
// To be safe, you should check that the SDCard is mounted
// using Environment.getExternalStorageState() before doing this.
File mediaStorageDir = new File(Environment.getExternalStoragePublicDirectory(
Environment.DIRECTORY_PICTURES), "MyCameraApp");
// This location works best if you want the created images to be shared
// between applications and persist after your app has been uninstalled.
// Create the storage directory if it does not exist
if (! mediaStorageDir.exists()){
if (! mediaStorageDir.mkdirs()){
Log.d("MyCameraApp", "failed to create directory");
return null;
}
}
// Create a media file name
String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss").format(new Date());
File mediaFile;
if (type == FileColumns.MEDIA_TYPE_IMAGE){
mediaFile = new File(mediaStorageDir.getPath() + File.separator +
"IMG_"+ timeStamp + ".jpg");
} else if(type == FileColumns.MEDIA_TYPE_VIDEO) {
mediaFile = new File(mediaStorageDir.getPath() + File.separator +
"VID_"+ timeStamp + ".mp4");
} else {
return null;
}
return mediaFile;
}
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
getWindow().addFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON);
mGestureDetector = createGestureDetector(this);
setContentView(R.layout.activity_main);
// Create an instance of Camera
mCamera = getCameraInstance();
if (gotCamera) {
// Create our Preview view and set it as the content of our activity.
Log.v(TAG,"We got the camera");
mPreview = new CameraPreview(this, mCamera);
FrameLayout preview = (FrameLayout) findViewById(R.id.camera_preview);
preview.addView(mPreview);
}
else {
finish();
}
}
private static Camera getCameraInstance(){
gotCamera = false;
Camera c = null;
try {
c = Camera.open(); // attempt to get a Camera instance
gotCamera = true;
}
catch (Exception e){
// Camera is not available (in use or does not exist)
Log.v(TAG,"Camera is not available!");
}
return c; // returns null if camera is unavailable
}
#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;
}
/*
* Send generic motion events to the gesture detector
*/
#Override
public boolean onGenericMotionEvent(MotionEvent event) {
if (mGestureDetector != null) {
return mGestureDetector.onMotionEvent(event);
}
return false;
}
private GestureDetector createGestureDetector(Context context) {
GestureDetector gestureDetector = new GestureDetector(context);
//Create a base listener for generic gestures
gestureDetector.setBaseListener( new GestureDetector.BaseListener() {
#Override
public boolean onGesture(Gesture gesture) {
if (gesture == Gesture.TAP) {
// do something on tap
Log.v(TAG,"tap");
// take a picture
takePic();
return true;
} else if (gesture == Gesture.TWO_TAP) {
// do something on two finger tap
return true;
} else if (gesture == Gesture.SWIPE_RIGHT) {
// do something on right (forward) swipe
return true;
} else if (gesture == Gesture.SWIPE_LEFT) {
// do something on left (backwards) swipe
return true;
}
return false;
}
});
gestureDetector.setFingerListener(new GestureDetector.FingerListener() {
#Override
public void onFingerCountChanged(int previousCount, int currentCount) {
// do something on finger count changes
}
});
gestureDetector.setScrollListener(new GestureDetector.ScrollListener() {
#Override
public boolean onScroll(float displacement, float delta, float velocity) {
// do something on scrolling
return false;
}
});
return gestureDetector;
}
private class CameraPreview extends SurfaceView implements SurfaceHolder.Callback {
private SurfaceHolder mHolder;
private Camera mCamera;
public CameraPreview(Context context, Camera camera) {
super(context);
mCamera = camera;
Log.v(TAG,"In CameraPreview");
// Install a SurfaceHolder.Callback so we get notified when the
// underlying surface is created and destroyed.
mHolder = getHolder();
Log.v(TAG,"Got holder");
mHolder.addCallback(this);
Log.v(TAG,"Added callback");
// 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 {
Log.v(TAG,"in surface created");
mCamera.setPreviewDisplay(holder);
Log.v(TAG,"set preview display");
mCamera.startPreview();
Log.v(TAG,"preview started");
} catch (IOException e) {
Log.d(TAG, "Error setting camera preview: " + e.getMessage());
}
}
public void surfaceDestroyed(SurfaceHolder holder) {
// empty. Take care of releasing the Camera preview in your activity.
mCamera.stopPreview();
mCamera.release();
mCamera = null;
}
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.
Log.v(TAG,"in surface changted");
if (mHolder.getSurface() == null){
// preview surface does not exist
Log.v(TAG,"surface don't exist");
return;
}
// stop preview before making changes
try {
mCamera.stopPreview();
Log.v(TAG,"stopped preview");
} catch (Exception e){
// ignore: tried to stop a non-existent preview
Log.v(TAG,"preview e");
}
// start preview with new settings
try {
Log.v(TAG,"startpreview");
mCamera.setPreviewDisplay(mHolder);
mCamera.startPreview();
} catch (Exception e){
Log.d(TAG, "Error starting camera preview: " + e.getMessage());
}
}
}
public void takePic() {
// get an image from the camera
mCamera.takePicture(null, null, mPicture);
}
}

The code you have for surfaceChanged looks fine, similar to what I have in my working Glass app. Have you checked the camera parameters passed to Camera.setParameters, such as preview size and focus mode? If you can post the full activity source in the question that would help finding the issue.

building camera app on android

hey there I'm new to app developing and I'm trying to build an app which includes the camera.
I followed the android developers guide and yet the app won't run, after trying to look for old answers in this site and not finding any that helped me, I'm asking for your help.
here's my code:
package com.example.camera;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.text.SimpleDateFormat;
import java.util.Date;
import android.app.Activity;
import android.content.Context;
import android.content.pm.PackageManager;
import android.hardware.Camera;
import android.hardware.Camera.PictureCallback;
import android.net.Uri;
import android.os.Bundle;
import android.os.Environment;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.FrameLayout;
public class MainActivity extends Activity {
public static final int MEDIA_TYPE_IMAGE = 1;
public static String TAG="MainActivity";
private Camera camera;
private CameraPreview preview;
private PictureCallback picture;
private FileNotFoundException err;
public static Camera getCameraInstance(){
Camera c = null;
try {
c = Camera.open(); // attempt to get a Camera insta
}
catch (Exception e){
// Camera is not available (in use or does not exist)
}
return c; // returns null if camera is unavailable
}
private boolean checkCameraHardware(Context context) {
if (context.getPackageManager().hasSystemFeature(PackageManager.FEATURE_CAMERA)){
// this device has a camera
return true;
} else {
// no camera on this device
return false;
}
}
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
camera = getCameraInstance();
preview = new CameraPreview(this, camera);
FrameLayout FLpreview = (FrameLayout) findViewById(R.id.camera_preview);
FLpreview.addView(preview);
picture = new PictureCallback() {
#Override
public void onPictureTaken(byte[] data, Camera camera) {
File pictureFile = getOutputMediaFile(MEDIA_TYPE_IMAGE);
if (pictureFile == null){
Log.d(TAG, "Error creating media file, check storage permissions: "+ err.getMessage());
return;
}
try {
FileOutputStream fos = new FileOutputStream(pictureFile);
fos.write(data);
fos.close();
} catch (FileNotFoundException e) {
Log.d(TAG, "File not found: " + e.getMessage());
} catch (IOException e) {
Log.d(TAG, "Error accessing file: " + e.getMessage());
}
}
};
Button captureButton = (Button) findViewById(R.id.button_capture);
captureButton.setOnClickListener(
new View.OnClickListener() {
#Override
public void onClick(View v) {
// get an image from the camera
camera.takePicture(null, null, picture);
}
}
);
}
/** A safe way to get an instance of the Camera object. */
private void releaseCamera(){
if (camera != null){
camera.release(); // release the camera for other applications
camera = null;
}
}
private static Uri getOutputMediaFileUri(int type){
return Uri.fromFile(getOutputMediaFile(type));
}
/** Create a File for saving an image or video */
private static File getOutputMediaFile(int type){
// To be safe, you should check that the SDCard is mounted
// using Environment.getExternalStorageState() before doing this.
File mediaStorageDir = new File(Environment.getExternalStoragePublicDirectory(
Environment.DIRECTORY_PICTURES), "MyCameraApp");
// This location works best if you want the created images to be shared
// between applications and persist after your app has been uninstalled.
// Create the storage directory if it does not exist
if (! mediaStorageDir.exists()){
if (! mediaStorageDir.mkdirs()){
Log.d("MyCameraApp", "failed to create directory");
return null;
}
}
// Create a media file name
String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss").format(new Date());
File mediaFile;
if (type == MEDIA_TYPE_IMAGE){
mediaFile = new File(mediaStorageDir.getPath() + File.separator +
"IMG_"+ timeStamp + ".jpg");
} else {
return null;
}
return mediaFile;
}
}
and here's the code for the surfaceholder:
package com.example.camera;
import java.io.IOException;
import android.content.Context;
import android.hardware.Camera;
import android.util.Log;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
public class CameraPreview extends SurfaceView implements SurfaceHolder.Callback {
private SurfaceHolder holder;
private Camera camera;
public static String TAG="MainActivity";
public CameraPreview(Context context, Camera cam) {
super(context);
camera=cam;
holder=getHolder();
holder.addCallback(this);
holder.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 {
camera.setPreviewDisplay(holder);
camera.startPreview();
} catch (IOException e) {
Log.d(TAG, "Error setting camera preview: " + e.getMessage());
}
}
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 (holder.getSurface() == null){
// preview surface does not exist
return;
}
// stop preview before making changes
try {
camera.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 {
camera.setPreviewDisplay(holder);
camera.setDisplayOrientation(0);
camera.startPreview();
} catch (Exception e){
Log.d(TAG, "Error starting camera preview: " + e.getMessage());
}
}
public void surfaceDestroyed(SurfaceHolder holder) {
// empty. Take care of releasing the Camera preview in your activity.
}
}
and lastly, Logcat:
07-31 12:06:06.361: W/Camera(998): ICamera died
07-31 12:06:06.361: W/Camera(998): Camera server died!
07-31 12:06:06.381: E/Camera(998): Error 100
Thanks a bunch!

Try to getCameraInstance() a bit later, e.g. onStart()

Error starting camera preview: startPreview failed

I am new to Java and android development. I am trying to open a camera in a app as shown in the android development sites.
I have a CameraActivity which calls the CameraPreview. As stated in the title, I get the error "startPreview failed". That is followed by "Camera server died!", "Icamera died", "Error 100".
This is my first time posting here, so I appologize if my format is the standard practice. Thank you for any help you can offer.
The code is as follows:
CameraPreview class:
package com.example.myfirstapp;
import java.io.IOException;
import android.content.Context;
import android.hardware.Camera;
import android.util.Log;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
public class CameraPreview extends SurfaceView implements SurfaceHolder.Callback {
private SurfaceHolder mHolder;
private Camera mCamera;
public static String TAG="CameraPreview";
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(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){
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(TAG, "Error starting camera preview: " + e.getMessage());
}
}
}
CameraActivity:
package com.example.myfirstapp;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.text.SimpleDateFormat;
import java.util.Date;
import android.app.Activity;
import android.hardware.Camera;
import android.hardware.Camera.PictureCallback;
import android.net.Uri;
import android.os.Bundle;
import android.os.Environment;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.FrameLayout;
public class CameraActivity extends Activity {
private Camera mCamera;
private CameraPreview mPreview;
private PictureCallback mPicture;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_take_picture);
// Create an instance of Camera
mCamera = getCameraInstance();
// Create our Preview view and set it as the content of our activity.
mPreview = new CameraPreview(this, mCamera);
FrameLayout preview = (FrameLayout) findViewById(R.id.camera_preview);
preview.addView(mPreview);
Button clickButton = (Button) findViewById(R.id.button_capture);
clickButton.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
// TODO Auto-generated method stub
mCamera.takePicture(null, null, mPicture);
}
});
mPicture = new PictureCallback() {
#Override
public void onPictureTaken(byte[] data, Camera camera) {
File pictureFile = getOutputMediaFile(MEDIA_TYPE_IMAGE);
if (pictureFile == null) {
Log.d("********","Error creating media file, check storage permissions: ");
return;
}
try {
FileOutputStream fos = new FileOutputStream(pictureFile);
fos.write(data);
fos.close();
Log.i("$$$$$$$$$", "file saved successfully....");
} catch (FileNotFoundException e) {
Log.e("********", "File not found: " + e.getMessage());
} catch (IOException e) {
Log.e("********", "Error accessing file: " + e.getMessage());
}
}
};
}
protected void onPause() {
super.onPause();
releaseCamera(); // release the camera immediately on pause event
}
private void releaseCamera() {
if (mCamera != null) {
mCamera.release(); // release the camera for other applications
mCamera = null;
}
}
public static Camera getCameraInstance() {
Camera c = null;
try {
c = Camera.open(); // attempt to get a Camera instance
} catch (Exception e) {
// Camera is not available (in use or does not exist)
}
return c; // returns null if camera is unavailable
}
public static final int MEDIA_TYPE_IMAGE = 1;
public static final int MEDIA_TYPE_VIDEO = 2;
/** Create a file Uri for saving an image or video */
private static Uri getOutputMediaFileUri(int type) {
return Uri.fromFile(getOutputMediaFile(type));
}
/** Create a File for saving an image or video */
private static File getOutputMediaFile(int type) {
// To be safe, you should check that the SDCard is mounted
// using Environment.getExternalStorageState() before doing this.
File mediaStorageDir = new File(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES),
"MyCameraApp");
// This location works best if you want the created images to be shared
// between applications and persist after your app has been uninstalled.
// Create the storage directory if it does not exist
if (!mediaStorageDir.exists()) {
if (!mediaStorageDir.mkdirs()) {
Log.d("MyCameraApp", "failed to create directory");
return null;
}
}
// Create a media file name
String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss")
.format(new Date());
File mediaFile;
if (type == MEDIA_TYPE_IMAGE) {
mediaFile = new File(mediaStorageDir.getPath() + File.separator
+ "IMG_" + timeStamp + ".jpg");
} else if (type == MEDIA_TYPE_VIDEO) {
mediaFile = new File(mediaStorageDir.getPath() + File.separator
+ "VID_" + timeStamp + ".mp4");
} else {
return null;
}
return mediaFile;
}
}
activity_take_picture (the xml layout)
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
>
<FrameLayout
android:id="#+id/camera_preview"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:layout_weight="1"
/>
<Button
android:id="#+id/button_capture"
android:text="Capture"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_gravity="center"
/>
</LinearLayout>

Android Camera App preview issue

I'd like to ask for some advice regarding the following problem. I'm currently working on a camera app for android and i am stuck. I used the official android development site for guidance, and the program is working fine except when i click the capture button for the first time the preview freezes and stays like that. Now, this is not causing the app to stop, because after the freezing i can still click the button and it takes the picture. I know this because if i check the save location the taken pictures are there.
So to summarize this mess, I'd like my program to show the preview continuously even after taking a picture. Any help would be appreciated!
My code:
My main activity:
package com.camera123.cr;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.text.SimpleDateFormat;
import java.util.Date;
import android.app.Activity;
import android.app.SearchManager.OnCancelListener;
import android.hardware.Camera;
import android.hardware.Camera.PictureCallback;
import android.hardware.Camera.ShutterCallback;
import android.media.CamcorderProfile;
import android.media.MediaRecorder;
import android.net.Uri;
import android.os.Bundle;
import android.os.Environment;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.FrameLayout;
public class Camera123 extends Activity{
/** Called when the activity is first created. */
private Camera mCamera;
private cameraPreview mPreview;
private MediaRecorder mMediaRecorder;
private boolean isRecording = false;
private Button captureButton;
FrameLayout preview;
public static final int MEDIA_TYPE_IMAGE = 1;
public static final int MEDIA_TYPE_VIDEO = 2;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
// Create an instance of Camera
mCamera = getCameraInstance();
// Create our Preview view and set it as the content of our activity.
mPreview = new cameraPreview(this, mCamera);
captureButton = (Button) findViewById(R.id.button_capture);
preview = (FrameLayout) findViewById(R.id.camera_preview);
preview.addView(mPreview);
captureButton.setOnClickListener(
new View.OnClickListener() {
#Override
public void onClick(View v) {
// get an image from the camera
mCamera.takePicture(null, null, mPicture);
}
}
);
}
/** A safe way to get an instance of the Camera object. */
public static Camera getCameraInstance(){
Camera c = null;
try {
c = Camera.open(); // attempt to get a Camera instance
if (c != null){
Camera.Parameters params = c.getParameters();
c.setParameters(params);
}
}
catch (Exception e){
Log.d("DEBUG", "Camera did not open");
// Camera is not available (in use or does not exist)
}
return c; // returns null if camera is unavailable
}
private PictureCallback mPicture = new PictureCallback() {
#Override
public void onPictureTaken(byte[] data, Camera camera) {
File pictureFile = getOutputMediaFile(MEDIA_TYPE_IMAGE);
if (pictureFile == null){
Log.d("DEBUG", "Error creating media file, check storage permissions: " /*+
e.getMessage()*/);
return;
}
try {
FileOutputStream fos = new FileOutputStream(pictureFile);
fos.write(data);
fos.close();
} catch (FileNotFoundException e) {
Log.d("DEBUG", "File not found: " + e.getMessage());
} catch (IOException e) {
Log.d("DEBUG", "Error accessing file: " + e.getMessage());
}
}
};
/** Create a file Uri for saving an image or video */
private static Uri getOutputMediaFileUri(int type){
return Uri.fromFile(getOutputMediaFile(type));
}
private static File getOutputMediaFile(int type){
// To be safe, you should check that the SDCard is mounted
// using Environment.getExternalStorageState() before doing this.
File mediaStorageDir = new File(Environment.getExternalStoragePublicDirectory(
Environment.DIRECTORY_PICTURES), "MyCameraApp");
// This location works best if you want the created images to be shared
// between applications and persist after your app has been uninstalled.
// Create the storage directory if it does not exist
if (! mediaStorageDir.exists()){
if (! mediaStorageDir.mkdirs()){
Log.d("MyCameraApp", "failed to create directory");
return null;
}
}
// Create a media file name
String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss").format(new Date());
File mediaFile;
if (type == MEDIA_TYPE_IMAGE){
mediaFile = new File(mediaStorageDir.getPath() + File.separator +
"IMG_"+ timeStamp + ".jpg");
} else if(type == MEDIA_TYPE_VIDEO) {
mediaFile = new File(mediaStorageDir.getPath() + File.separator +
"VID_"+ timeStamp + ".mp4");
} else {
return null;
}
return mediaFile;
}
private void releaseCamera(){
if (mCamera != null){
isRecording = false;
mCamera.stopPreview();
mCamera.setPreviewCallback(null);
mCamera.release(); // release the camera for other applications
mCamera = null;
}
}
}
My Preview Class:
package com.camera123.cr;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.hardware.Camera;
import android.hardware.Camera.PreviewCallback;
import android.util.Log;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
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("DEBUG", "Error setting camera preview: " + e.getMessage());
}
}
public void surfaceDestroyed(SurfaceHolder holder) {
}
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("DEBUG", "Error starting camera preview: " + e.getMessage());
}
}
}
My main.xml file:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="horizontal"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
>
<FrameLayout
android:id="#+id/camera_preview"
android:layout_width="fill_parent"
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>
And my Manifest:
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.camera123.cr"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk android:minSdkVersion="8" />
<uses-permission android:name="android.permission.CAMERA" />
<uses-feature android:name="android.hardware.camera" />
<uses-permission android:name="android.permission.RECORD_AUDIO" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.RECORD_VIDEO" />
<application
android:icon="#drawable/ic_launcher"
android:label="#string/app_name" >
<activity
android:name=".Camera123"
android:label="#string/app_name"
android:screenOrientation="landscape">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>

I don't think it's well documented, but taking the picture actually stops your preview. Place:
mCamera.startPreview();
in your onPictureTaken() method in the PictureCallback to restart it after capture is complete.