I have a camera app that had a Camera Preview which worked. The app was developed some years ago (2012) and i decided to reuse parts of its code, but, upon testing again (on same hardware i9100, different OS 4.4 vs 3.0), my camera preview image has a problem
when i move the phone, i see the image change and it responds to light and dark patterns (therefore app is communicating with camera).
this is my code (it uses deprecated method setType):
class CameraPreview extends SurfaceView implements SurfaceHolder.Callback {
private static final String TAG = "TGCamera";
SurfaceHolder mHolder;
public Camera camera;
public final String fileName = "/download/CameraGPS/zdelTempPhotoPreview.jpg";
CameraPreview(Context context) {
super(context);
// Install a SurfaceHolder.Callback so we get notified when the
// underlying surface is created and destroyed.
mHolder = getHolder();
mHolder.addCallback(this);
mHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
}
public void surfaceCreated(SurfaceHolder holder) {
// The Surface has been created, acquire the camera and tell it where
// to draw.
camera = Camera.open();
Parameters parameter02 = camera.getParameters();
parameter02.setJpegThumbnailSize(80, 60);
parameter02.setPictureSize(640, 480);
camera.setParameters(parameter02);
try {
camera.setPreviewDisplay(holder);
camera.setDisplayOrientation(90);
Parameters parameters00 = camera.getParameters();
//parameters00.setRotation(90);
//parameters00.setFlashMode("on");
//parameters00.setJpegQuality(20);
camera.setParameters(parameters00);
camera.setPreviewCallback(new PreviewCallback() {
public void onPreviewFrame(byte[] data, Camera arg1) {
CameraPreview.this.invalidate();
}
});
} catch (IOException e) {
e.printStackTrace();
}
}
public void surfaceDestroyed(SurfaceHolder holder) {
// Surface will be destroyed when we return, so stop the preview.
// Because the CameraDevice object is not a shared resource, it's very
// important to release it when the activity is paused.
camera.stopPreview();
camera = null;
}
public void surfaceChanged(SurfaceHolder holder, int format, int w, int h) {
// Now that the size is known, set up the camera parameters and begin
// the preview.
//camera.getParameters().setRotation();
//camera.getParameters().setJpegQuality(20);
//camera.getParameters().setPictureSize(width, height)
Parameters parameters = camera.getParameters();
parameters.setPreviewSize(w, h);
camera.setParameters(parameters);
camera.startPreview();
}
#Override
public void draw(Canvas canvas) {
super.draw(canvas);
Log.w(TAG,"clicked in preview");
Paint p = new Paint(Color.RED);
Log.d(TAG, "draw");
canvas.drawText("PREVIEW", canvas.getWidth() / 2,
canvas.getHeight() / 2, p);
}
Any suggestions?
You cannot set the picture size and preview size to arbitrary values. Make sure you check the lists returned by getSupportedPictureSizes() and getSupportedPreviewSizes(), respectively.
Often (I don't remember if this applies to Samsung Galaxy S2), the camera does not work correctly when the aspect ratio for picture is different from the one for preview.
Furthermore, you are not supposed to draw on the preview surface, and definitely not from onPreviewFrame() callback.
The first thing would be to add camera.setPreviewDisplay(holder) in your surfaceChanged() method too
Update:
Please debug in surfaceCreated and surfaceChanged that holder.getSurface() != null
Also you should add camera.release() in surfaceDestroyed and then clean install app (uninstall first and then fresh install the app). The camera service could be hanging since a previous run of the app.
Update 2:
I just noticed that you missed registering to callbacks from the SurfaceHolder passed by the surfaceCreated() and surfaceChanged() methods. In this case it would make sense that surfaceChanged() is never reached and that means startPreview() is never actually called..
In surfaceCreated and surfaceChanged methods, please update the code to include:
mHolder.removeCallback(this); // unregister from old SurfaceHolder
holder.addCallback(this); // register to new holder
try {
camera.setPreviewDisplay(holder);
} catch (IOException e) {
e.printStackTrace();
}
mHolder = holder;
I just started to develop an Android app that needs to use camera features in order to capture images and I want to keep the Flash ALWAYS ON. The problem is that when I start the camera from app the flash only blinks once and stops.
I implemented the camera with Camera class and I used the CameraPreview that extends SurfaceView and implements SurfaceHolder exactly like the example from android developer page: Here
Then I used a FrameLayout to show the camera preview:
// Create an instance of Camera
mCamera = getCameraInstance();
Parameters p = mCamera.getParameters();
p.setFlashMode(Parameters.FLASH_MODE_TORCH);
mCamera.setParameters(p);
// 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);
Everything works good excepting the flash that blinks once and stops.
I tested the app on a Samsung Galaxy S5 with KitKat.
Intent for camera don't fit my needs and Camera2 is excluded.
Thanks!
Found the solution:
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 {
//Turn flash on
Camera.Parameters p = mCamera.getParameters();
p.setFlashMode(Camera.Parameters.FLASH_MODE_TORCH);
mCamera.setParameters(p);
mCamera.setPreviewDisplay(mHolder);
mCamera.startPreview();
} catch (Exception e){
Log.d(TAG, "Error starting camera preview: " + e.getMessage());
}
}
Add the code to start the flash in the second try-catch of surfaceChanged method.
I have used zbar scanner for android and it captures the barcodes quite easily.
But the problem is that on phones which have autofocus, it captures the barcodes too quickly to detect it correctly.
If only it could wait for a few milliseconds more, it could then be able to capture more clearer image and thereby not show "not found" page.
How can I solve this problem?
Is there a provision to delay the focus on the barcode?
Maybe a delay in capturing the image?
Are you talking about the example code, CameraTestActivity.java?
Implement a counter that counts for similar scanning results. If the scanning result remains the same (e.g. for 10 times in a row), we can assume the result is quite reliable.
I really like #Juuso_Ohtonen's reply, and actually just used it in my own reader, however if you want an AutoFocus delay you can create a Camera.AutoFocusCallback object and implement its onAutoFocus method with a .postDelayed. This object is then used on your Camera camera.autoFocus() method.
// Mimic continuous auto-focusing
Camera.AutoFocusCallback autoFocusCB = new Camera.AutoFocusCallback() {
public void onAutoFocus(boolean success, Camera camera) {
autoFocusHandler.postDelayed(doAutoFocus, 1000);
}
};
This section is used in the class that extends SurfaceView, which then implements surfaceChanged();
public CameraPreview(Context context, Camera camera,
PreviewCallback previewCb,
AutoFocusCallback autoFocusCb) {
super(context);
mCamera = camera;
previewCallback = previewCb;
autoFocusCallback = autoFocusCb;
// 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 surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
/*
* 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
}
try {
mCamera.setPreviewDisplay(mHolder);
mCamera.setPreviewCallback(previewCallback);
mCamera.startPreview();
mCamera.autoFocus(autoFocusCallback);
} catch (Exception e) {
Log.d("DBG", "Error starting camera preview: " + e.getMessage());
}
}
when using the Camera.PreviewCallback implementation the onPreviewFrame is called without problem after initializing camera and starting preview (Camera.startPrevew()). The problem is if I make a video recording using MediaRecorder onPreviewFrame does not get called any more.
I understand that when using MediaRecorder to record video stops the Camera.PreviewCallback, but why can't it be restarted?
I have tried resetting the camera preview callback (setPreviewCallback(callback)) and restarting startPreview, but while I have a preview there is no call to onPreviewFrame.
You must call setPreviewCallback in the surfaceChanged method, not only in the surfaceCreated.
public void surfaceChanged(SurfaceHolder holder, int format, int w, int h) {
if (mHolder.getSurface() == null){
return;
}
try {
mCamera.stopPreview();
} catch (Exception e){
// ignore: tried to stop a non-existent preview
}
try {
mCamera.setPreviewCallback(this);
mCamera.setPreviewDisplay(mHolder);
mCamera.startPreview();
} catch (Exception e){
Log.d(TAG, "Error starting camera preview: " + e.getMessage());
}
}
I had a similar problem; see
setOneShotPreviewCallback not hitting onPreviewFrame() in callback
What I discovered was that after calling Camera#unlock() to prepare the MediaRecorder, it was necessary to call Camera#reconnect() before setting the preview callback. This is because Camera.unlock() detaches the camera from the process to let the MediaRecorder connect to it.
http://developer.android.com/reference/android/hardware/Camera.html#unlock()
In my investigations I also discovered that if you set any preview callbacks using other methods than the one shot method, you have to reset all of these after calling Camera#reconnect() as well. So, briefly:
mCamera.unlock();
//set up MediaRecorder
mCamera.reconnect();
mCamera.setPreviewCallback(mCallback);
//or whatever callback method you want to use
//and even if you've set this callback already
I hope that helps!
You should call it within new instantiation of previewCallBacks() interface, like below
public void surfaceCreated(SurfaceHolder holder) {
// if (mediaRecorder == null) {
try {
camera = Camera.open();
camera.setPreviewCallback(new PreviewCallback() {
public void onPreviewFrame(byte[] _data, Camera _camera) {
}
}
}
}
You need to call startPreview() again after a video or photo was taken.
I am writing an Android 1.5 application which starts just after boot-up. This is a Service and should take a picture without preview. This app will log the light density in some areas whatever. I was able to take a picture but the picture was black.
After researching for a long time, I came across a bug thread about it. If you don't generate a preview, the image will be black since Android camera needs preview to setup exposure and focus. I've created a SurfaceView and the listener, but the onSurfaceCreated() event never gets fired.
I guess the reason is, the surface is not being created visually. I've also seen some examples of calling the camera statically with MediaStore.CAPTURE_OR_SOMETHING which takes a picture and saves in the desired folder with two lines of code, but it doesn't take a picture too.
Do I need to use IPC and bindService() to call this function? Or is there an alternative method to achieve this?
it is really weird that camera on android platform can't stream video until it given valid preview surface. it seems that the architects of the platform was not thinking about 3rd party video streaming applications at all. even for augmented reality case the picture can be presented as some kind of visual substitution, not real time camera stream.
anyway, you can simply resize preview surface to 1x1 pixels and put it somewhere in the corner of the widget (visual element). please pay attention - resize preview surface, not camera frame size.
of course such trick does not eliminate unwanted data streaming (for preview) which consumes some system resources and battery.
I found the answer to this in the Android Camera Docs.
Note: It is possible to use MediaRecorder without creating a camera
preview first and skip the first few steps of this process. However,
since users typically prefer to see a preview before starting a
recording, that process is not discussed here.
You can find the step by step instructions at the link above. After the instructions, it will state the quote that I have provided above.
Actually it is possible, but you have to fake the preview with a dummy SurfaceView
SurfaceView view = new SurfaceView(this);
c.setPreviewDisplay(view.getHolder());
c.startPreview();
c.takePicture(shutterCallback, rawPictureCallback, jpegPictureCallback);
Update 9/21/11: Apparently this does not work for every Android device.
Taking the Photo
Get this working first before trying to hide the preview.
Correctly set up the preview
Use a SurfaceView (pre-Android-4.0 compatibility) or SurfaceTexture (Android 4+, can be made transparent)
Set and initialise it before taking the photo
Wait for the SurfaceView's SurfaceHolder (via getHolder()) to report surfaceCreated() or the TextureView to report onSurfaceTextureAvailable to its SurfaceTextureListener before setting and initialising the preview.
Ensure the preview is visible:
Add it to the WindowManager
Ensure its layout size is at least 1x1 pixels (you might want to start by making it MATCH_PARENT x MATCH_PARENT for testing)
Ensure its visibility is View.VISIBLE (which seems to be the default if you don't specify it)
Ensure you use the FLAG_HARDWARE_ACCELERATED in the LayoutParams if it's a TextureView.
Use takePicture's JPEG callback since the documentation says the other callbacks aren't supported on all devices
Troubleshooting
If surfaceCreated/onSurfaceTextureAvailable doesn't get called, the SurfaceView/TextureView probably isn't being displayed.
If takePicture fails, first ensure the preview is working correctly. You can remove your takePicture call and let the preview run to see if it displays on the screen.
If the picture is darker than it should be, you might need to delay for about a second before calling takePicture so that the camera has time to adjust its exposure once the preview has started.
Hiding the Preview
Make the preview View 1x1 size to minimise its visibility (or try 8x16 for possibly more reliability)
new WindowManager.LayoutParams(1, 1, /*...*/)
Move the preview out of the centre to reduce its noticeability:
new WindowManager.LayoutParams(width, height,
Integer.MIN_VALUE, Integer.MIN_VALUE, /*...*/)
Make the preview transparent (only works for TextureView)
WindowManager.LayoutParams params = new WindowManager.LayoutParams(
width, height, /*...*/
PixelFormat.TRANSPARENT);
params.alpha = 0;
Working Example (tested on Sony Xperia M, Android 4.3)
/** Takes a single photo on service start. */
public class PhotoTakingService extends Service {
#Override
public void onCreate() {
super.onCreate();
takePhoto(this);
}
#SuppressWarnings("deprecation")
private static void takePhoto(final Context context) {
final SurfaceView preview = new SurfaceView(context);
SurfaceHolder holder = preview.getHolder();
// deprecated setting, but required on Android versions prior to 3.0
holder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
holder.addCallback(new Callback() {
#Override
//The preview must happen at or after this point or takePicture fails
public void surfaceCreated(SurfaceHolder holder) {
showMessage("Surface created");
Camera camera = null;
try {
camera = Camera.open();
showMessage("Opened camera");
try {
camera.setPreviewDisplay(holder);
} catch (IOException e) {
throw new RuntimeException(e);
}
camera.startPreview();
showMessage("Started preview");
camera.takePicture(null, null, new PictureCallback() {
#Override
public void onPictureTaken(byte[] data, Camera camera) {
showMessage("Took picture");
camera.release();
}
});
} catch (Exception e) {
if (camera != null)
camera.release();
throw new RuntimeException(e);
}
}
#Override public void surfaceDestroyed(SurfaceHolder holder) {}
#Override public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {}
});
WindowManager wm = (WindowManager)context
.getSystemService(Context.WINDOW_SERVICE);
WindowManager.LayoutParams params = new WindowManager.LayoutParams(
1, 1, //Must be at least 1x1
WindowManager.LayoutParams.TYPE_SYSTEM_OVERLAY,
0,
//Don't know if this is a safe default
PixelFormat.UNKNOWN);
//Don't set the preview visibility to GONE or INVISIBLE
wm.addView(preview, params);
}
private static void showMessage(String message) {
Log.i("Camera", message);
}
#Override public IBinder onBind(Intent intent) { return null; }
}
On Android 4.0 and above (API level >= 14), you can use TextureView to preview the camera stream and make it invisible so as to not show it to the user. Here's how:
First create a class to implement a SurfaceTextureListener that will get the create/update callbacks for the preview surface. This class also takes a camera object as input, so that it can call the camera's startPreview function as soon as the surface is created:
public class CamPreview extends TextureView implements SurfaceTextureListener {
private Camera mCamera;
public CamPreview(Context context, Camera camera) {
super(context);
mCamera = camera;
}
#Override
public void onSurfaceTextureAvailable(SurfaceTexture surface, int width, int height) {
Camera.Size previewSize = mCamera.getParameters().getPreviewSize();
setLayoutParams(new FrameLayout.LayoutParams(
previewSize.width, previewSize.height, Gravity.CENTER));
try{
mCamera.setPreviewTexture(surface);
} catch (IOException t) {}
mCamera.startPreview();
this.setVisibility(INVISIBLE); // Make the surface invisible as soon as it is created
}
#Override
public void onSurfaceTextureSizeChanged(SurfaceTexture surface, int width, int height) {
// Put code here to handle texture size change if you want to
}
#Override
public boolean onSurfaceTextureDestroyed(SurfaceTexture surface) {
return true;
}
#Override
public void onSurfaceTextureUpdated(SurfaceTexture surface) {
// Update your view here!
}
}
You'll also need to implement a callback class to process the preview data:
public class CamCallback implements Camera.PreviewCallback{
public void onPreviewFrame(byte[] data, Camera camera){
// Process the camera data here
}
}
Use the above CamPreview and CamCallback classes to setup the camera in your activity's onCreate() or similar startup function:
// Setup the camera and the preview object
Camera mCamera = Camera.open(0);
CamPreview camPreview = new CamPreview(Context,mCamera);
camPreview.setSurfaceTextureListener(camPreview);
// Connect the preview object to a FrameLayout in your UI
// You'll have to create a FrameLayout object in your UI to place this preview in
FrameLayout preview = (FrameLayout) findViewById(R.id.cameraView);
preview.addView(camPreview);
// Attach a callback for preview
CamCallback camCallback = new CamCallback();
mCamera.setPreviewCallback(camCallback);
There is a way of doing this but it's somewhat tricky.
what should be done, is attach a surfaceholder to the window manager from the service
WindowManager wm = (WindowManager) mCtx.getSystemService(Context.WINDOW_SERVICE);
params = new WindowManager.LayoutParams(WindowManager.LayoutParams.WRAP_CONTENT,
WindowManager.LayoutParams.WRAP_CONTENT,
WindowManager.LayoutParams.TYPE_SYSTEM_OVERLAY,
WindowManager.LayoutParams.FLAG_WATCH_OUTSIDE_TOUCH,
PixelFormat.TRANSLUCENT);
wm.addView(surfaceview, params);
and then set
surfaceview.setZOrderOnTop(true);
mHolder.setFormat(PixelFormat.TRANSPARENT);
where mHolder is the holder you get from the surface view.
this way, you can play with the surfaceview's alpha, make it completly transparent, but the camera will still get frames.
that's how i do it. hope it helps :)
We solved this problem by using a dummy SurfaceView (not added to actual GUI) in versions below 3.0 (or let's say 4.0 as a camera service on a tablet does not really make sense).
In versions >= 4.0 this worked in the emulator only ;(
The use of SurfaceTexture (and setSurfaceTexture()) instead of SurfaceView (and setSurfaceView()) worked here. At least this works on Nexus S.
I think this really is a shortcoming of the Android framework.
In the "Working Example by Sam" (Thank you Sam... )
if at istruction "wm.addView(preview, params);"
obtain exception "Unable to add window android.view.ViewRoot -- permission denied for this window type"
resolve by using this permission in AndroidManifest:
<uses-permission android:name="android.permission.SYSTEM_ALERT_WINDOW"/>
You can try this working code, This service click front picture, if you want to capture back camera picture then uncomment back camera in code and comment front camera.
Note :- Allow Camera and Storage permission to App And startService from Activity or anywhere.
public class MyService extends Service {
#Nullable
#Override
public IBinder onBind(Intent intent) {
return null;
}
#Override
public void onCreate() {
super.onCreate();
CapturePhoto();
}
private void CapturePhoto() {
Log.d("kkkk","Preparing to take photo");
Camera camera = null;
Camera.CameraInfo cameraInfo = new Camera.CameraInfo();
int frontCamera = 1;
//int backCamera=0;
Camera.getCameraInfo(frontCamera, cameraInfo);
try {
camera = Camera.open(frontCamera);
} catch (RuntimeException e) {
Log.d("kkkk","Camera not available: " + 1);
camera = null;
//e.printStackTrace();
}
try {
if (null == camera) {
Log.d("kkkk","Could not get camera instance");
} else {
Log.d("kkkk","Got the camera, creating the dummy surface texture");
try {
camera.setPreviewTexture(new SurfaceTexture(0));
camera.startPreview();
} catch (Exception e) {
Log.d("kkkk","Could not set the surface preview texture");
e.printStackTrace();
}
camera.takePicture(null, null, new Camera.PictureCallback() {
#Override
public void onPictureTaken(byte[] data, Camera camera) {
File pictureFileDir=new File("/sdcard/CaptureByService");
if (!pictureFileDir.exists() && !pictureFileDir.mkdirs()) {
pictureFileDir.mkdirs();
}
SimpleDateFormat dateFormat = new SimpleDateFormat("yyyymmddhhmmss");
String date = dateFormat.format(new Date());
String photoFile = "ServiceClickedPic_" + "_" + date + ".jpg";
String filename = pictureFileDir.getPath() + File.separator + photoFile;
File mainPicture = new File(filename);
try {
FileOutputStream fos = new FileOutputStream(mainPicture);
fos.write(data);
fos.close();
Log.d("kkkk","image saved");
} catch (Exception error) {
Log.d("kkkk","Image could not be saved");
}
camera.release();
}
});
}
} catch (Exception e) {
camera.release();
}
}
}