camera

Make new project – Give permission to use camera Make button called TakePicture Make button called ShowLastPic Add SurfaceView to layout – Surface view is something we can draw on – This will show the picture preview – Set layout height = fill_parent (or try 10dip) – Set layout width = fill_parent – Set layout weight = 1 – Id SurfaceView changes when the phone’s orientation changes.

To handle the surface and changes in the surface, we need our activity to implement SurfaceHolder.Callback. – public class MyCamera extends Activity implements SurfaceHolder.Callback { Our MyCamera class needs some objects – Camera mCamera; // to hold the camera object – private SurfaceView mSurfaceView; // to hold the surface view – private SurfaceHolder mSurfaceHolder; // to hold the interface for the surfacevieww – We’ll add some more later After super.onCreate – setContentView(R.layout.main); – mSurfaceView = (SurfaceView) findViewById(R.id.surface_camera); // get surface object – mSurfaceHolder = mSurfaceView.getHolder();// get surface holder – mSurfaceHolder.addCallback(this);// this activity is the callback – // note, instead this, we could make a new classss that implements SurfcaeHolder.Callback – mSurfaceHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS); // says ? Implementing SurfaceHolder.CallBack requires three functions to be implemented – surfaceCreated – surfaceChanged Called when orientation is changed and after surfaceCreated – surfaceDestroyed

public void surfaceCreated(SurfaceHolder holder) { Log.e("My camera app", "surfaceCreated"); mCamera = Camera.open();}

public void surfaceChanged(SurfaceHolder holder, int format, int w, int h) { Log.d("My camera app", "surfaceChanged"); But mCamera.stopPreview() requires that startPreview was called mCamera.stopPreview(); mCamera.startPreview(); …. Set up preview ….

public void surfaceChanged(SurfaceHolder holder, int format, int w, int h) { Log.d(“My camera app”, "surfaceChanged"); If (previewRunning) mCamera.stopPreview(); mCamera.startPreview(); previewRunning = true; …. Set up preview …. boolean previewRunning = false;

public void surfaceChanged(SurfaceHolder holder, int format, int w, int h) { Log.d(“My camera app”, "surfaceChanged"); if (previewRunning) { mCamera.stopPreview(); } Log.e("My camera app","view width"+w+" height"+h); Camera.Parameters p = mCamera.getParameters(); // set the preview size p.setPreviewSize(w, h); mCamera.setParameters(p); try { mCamera.setPreviewDisplay(holder); } catch (IOException e) { e.printStackTrace(); } mCamera.startPreview(); mPreviewRunning = true; }

public void surfaceDestroyed(SurfaceHolder holder) { Log.e("My camera app", "surfaceDestroyed"); mCamera.stopPreview(); mCamera.release(); previewRunning = false;}

run It crashes on nexus 1 Check log Note that error when setting preview size Note that preview size is odd. Check web for more info on Camera.Parameters and Camera.Parameters.setPreviewSize – see getSupportedPreviewSizes

Log.e("My camera app","width"+w+" h"+h); List sizes = mCamera.getParameters().getSupportedPreviewSizes(); Camera.Size sizeToSet = null; for (Camera.Size t: sizes) { String str = "view"; str += t.width; str += "by" + t.height; Log.e("My camera app”, str); } Log.e("My camera app“,"w="+sizeToSet.width+" h="+sizeToSet.height); Before setParameters, do the following if (t.width<=w && t.height<=h && found==false) { sizeToSet = t; found = true; } Boolean found = new Boolean(false); add Inside loop, add

Camera.Parameters p = mCamera.getParameters(); p.setPreviewSize(sizeToSet.width, sizeToSet.height); mCamera.setParameters(p); Change parameter setting to:

Rotation/orientation Note that the orientation is messed up – Perhaps the image is correct in only one orientation. Two fixes – Fix the orientation to be in portrait or landscape and set display orientation accordingly In onCreate, add – setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_PORTRAIT); In surfaceChanged, add – mCamera.setDisplayOrientation(180); // or whatever value works – Get the rotation and then set camera orientation accordingly In surfaceChanged, add – Display display = getWindowManager().getDefaultDisplay(); – switch (display.getRotation()) { » case Surface.ROTATION_0: Log.e("DEBUG INFO","rotation = 0"); mCamera.setDisplayOrientation(180); // whatever value works break; » case Surface.ROTATION_90: Etc. etc.

Take picture In onCreate add button click listener – When clicked call previewRunning = false; mCamera.stopPreview (); mCamera.takePicture(null, null, pictureCallback); – The first null could be set to play a sound. But we will just use the default – pictureCallback is a Camera.PictureCallback object that we must make

Where to save files? Private directories – Only accessible by this app (cannot share files) – Deleted when app is uninstalled – Can be on internal memory or external (e.g., sdcard) External Storage Directory – Might be on sdcard or internal memory – Can be mounted on another machine when attaching phone to laptop via usb, the external memory is accessible by the laptop and might not be accessible by the phone apps – No standard directories, so files can get messy. Hence not recommended unless you are careful to clean up after yourself External Storage Public Directory – Like External Storage Directory, but uses specific directories e.g., pictures, music, video

External storage Before external storage is used, the app must check that the storage is accessible – If the phone is attached to a computer via usb, the storage might not be accessible because the computer is controlling the storage device boolean mExternalStorageAvailable = false; boolean mExternalStorageWriteable = false; String state = Environment.getExternalStorageState(); if (Environment.MEDIA_MOUNTED.equals(state)) { – // We can read and write the media – mExternalStorageAvailable = mExternalStorageWriteable = true; – Log.e("DEBUG INFO","storage is readble and writable"); } else if (Environment.MEDIA_MOUNTED_READ_ONLY.equals(state)) { – // We can only read the media – mExternalStorageAvailable = true; – mExternalStorageWriteable = false; – Log.e("DEBUG INFO","storage is readable only"); } else { – // Something else is wrong. It may be one of many other states, but all we need – // to know is we can neither read nor write – mExternalStorageAvailable = mExternalStorageWriteable = false; – Log.e("DEBUG INFO","storage is not accessible"); }

External Storage Public Directory If external storage is available, we can get the directory if (mExternalStorageWriteable) { – File path = Environment.getExternalStoragePublicDirectory(Environment.DIRECTO RY_PICTURES); – // arg must not be null, can be DIRECTORY_MUSIC, DIRECTORY_PODCASTS, DIRECTORY_RINGTONES, DIRECTORY_ALARMS, DIRECTORY_NOTIFICATIONS, DIRECTORY_PICTURES, DIRECTORY_MOVIES, DIRECTORY_DOWNLOADS, or DIRECTORY_DCIM – Pcitures and videos from camera // this is a small set of directories – path.mkdirs(); – File file = new File(path, "my_pic.jpeg");

External Storage Directory if (mExternalStorageWriteable) { – File path = Environment. getExternalStorageDirectory(); – File file = new File(path, "my_pic.jpeg");

Application Storage Internal storage: only accessible by the applications. Security is enforced – File path = getFilesDir(); – File file = new File(path, "my_pic.jpeg"); External storage. Typically not visible to user media applications (e.g., if you store a movie here, your movie player will not find it) No security enforcement. So other applications could overwrite – File path = getExternalFilesDir (type); // type is DIRECTORY_MUSIC, DIRECTORY_PODCASTS, DIRECTORY_RINGTONES, DIRECTORY_ALARMS, DIRECTORY_NOTIFICATIONS, DIRECTORY_PICTURES, or DIRECTORY_MOVIES. Or null – File file = new File(path, "my_pic.jpeg");

Camera.PictureCallback mPictureCallback = new Camera.PictureCallback() { public void onPictureTaken(byte[] imageData, Camera c) { if (imageData == null) { Log.e("DEBUG INFO","image is null"); } else { // get file as just explained We will use Bitmap, which has lots of bitmap related functions To write to a jpeg file, we use Bitmap.compress(file format, quality, outputStream); Bitmap bitmap = BitmapFactory.decodeByteArray(imageData,0,imageData.length); To create a Bitmap we use BitmapFactory. decodeByteArray(byte[] data, int offset, int length) Where data is imageData (the function argument,; offset = 0; and length = imageData.length FileOutputStream fos = new FileOutputStream(file); bitmap.compress(CompressFormat.JPEG, 50, fos); // quality is 50, but could be between 0 and 100 fos.close(); previewRunning = false; mCamera.startPreview(); Finally, start the preview again: add

Show picture Make new activity (see previous tutorial on making another activity) In layout add – Add ImageView In onCreate String pathForAppFiles = getFilesDir().getAbsolutePath(); pathForAppFiles = pathForAppFiles + "/" + "myPic.jpeg"; Log.d("Still image source filename:", pathForAppFiles); Get file name Get bitmap from file Bitmap bm = BitmapFactory.decodeFile(pathForAppFiles); Show bitmap in ImageView ImageView imageView = (ImageView)this.findViewById(R.id.ImageView); imageView.setImageBitmap(bm);