camera

1. camera

2. 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 = @+id/surface_camera • SurfaceView changes when the phone’s orientation changes.

3. 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 SurfaceViewmSurfaceView; // to hold the surface view • private SurfaceHoldermSurfaceHolder; // 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

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

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

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

7. 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; }

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

9. 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

10. Before setParameters, do the following Log.e("My camera app","width"+w+" h"+h); List<Camera.Size> 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); add Boolean found = new Boolean(false); Inside loop, add if (t.width<=w && t.height<=h && found==false) { sizeToSet = t; found = true; }

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

12. 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.

13. 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

14. 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

15. 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 • booleanmExternalStorageAvailable = false; • booleanmExternalStorageWriteable = 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"); • }

16. External Storage Public Directory • If external storage is available, we can get the directory • if (mExternalStorageWriteable) { • File path = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_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");

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

18. 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");

19. Camera.PictureCallbackmPictureCallback = 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 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 add Bitmap bitmap = BitmapFactory.decodeByteArray(imageData,0,imageData.length); To write to a jpeg file, we use Bitmap.compress(file format, quality, outputStream); add FileOutputStreamfos= new FileOutputStream(file); bitmap.compress(CompressFormat.JPEG, 50, fos); // quality is 50, but could be between 0 and 100 fos.close(); Finally, start the preview again: • previewRunning = false; • mCamera.startPreview();

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