Why does the continuous autofocus camera with the processor not allow switching the camera flash?

Question

What i have done so far:

I have a custom qr code reader camera that should continue to focus the camera for better qr reading.

My problem is that I use the camera flash handler on the \ off button to focus every second, it doesn’t work, or it takes too much time to turn the camera flash on and off. Everything works fine when I delete the auto focus code of the camera every second (Runnable and handler).

I want to automatically and quickly focus when the camera moves, and can also quickly and quickly turn the flash on and off without using Camera.Parameters.FOCUS_MODE_CONTINUOUS_PICTURE , because it is not available for API<14 .

I used Camera.Parameters.FOCUS_MODE_AUTO , but its only focusing of the camera once started, so I used a handler to focus the camera every second.

Min SDK Project version - 9.

My camera activity

 public class CameraActivityNew extends Activity implements OnClickListener, Camera.PreviewCallback { CameraPreviewNew mPreview; FrameLayout flCameraPreview; ImageButton ibFlashButton; Boolean isFlashOn = false; Camera mCamera; private Handler mAutoFocusHandler; private boolean mPreviewing = true; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); requestWindowFeature(Window.FEATURE_NO_TITLE); getWindow().addFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN); mAutoFocusHandler = new Handler(); setContentView(R.layout.activity_camera); findSetupViews(); mPreview = new CameraPreviewNew(getApplicationContext(), this, autoFocusCB); flCameraPreview.addView(mPreview); } private Runnable doAutoFocus = new Runnable() { public void run() { if (mCamera != null && mPreviewing) { mCamera.autoFocus(autoFocusCB); } } }; Camera.AutoFocusCallback autoFocusCB = new Camera.AutoFocusCallback() { public void onAutoFocus(boolean success, Camera camera) { mAutoFocusHandler.postDelayed(doAutoFocus, 1000); } }; @Override protected void onResume() { super.onResume(); try { mCamera = Camera.open(); if (mCamera == null) { return; } } catch (Exception e) { e.printStackTrace(); return; } mPreview.setCamera(mCamera); mPreview.showSurfaceView(); mPreviewing = true; } @Override protected void onPause() { super.onPause(); if (mCamera != null) { mPreview.setCamera(null); mCamera.cancelAutoFocus(); mCamera.setPreviewCallback(null); mCamera.stopPreview(); mCamera.release(); mPreview.hideSurfaceView(); mPreviewing = false; mCamera = null; } } private void findSetupViews() { flCameraPreview = (FrameLayout) findViewById(R.id.flCameraPreview); ibFlashButton = (ImageButton) findViewById(R.id.ibFlash); ibFlashButton.setOnClickListener(this); if (getPackageManager().hasSystemFeature( PackageManager.FEATURE_CAMERA_FLASH)) { ibFlashButton.setVisibility(View.VISIBLE); ibFlashButton.setOnClickListener(this); } else { ibFlashButton.setVisibility(View.GONE); } } @Override public void onClick(View v) { switch (v.getId()) { case R.id.ibFlash: if (isFlashOn) { mPreview.setCameraFlashLight(false); isFlashOn = false; ibFlashButton.setImageResource(R.drawable.flashoff); } else { mPreview.setCameraFlashLight(true); ibFlashButton.setImageResource(R.drawable.flashon); isFlashOn = true; } break; } } @Override public void onPreviewFrame(final byte[] data, final Camera camera) { // processed here qr code and works fine if camera focus //now removed to narrow the code for posting the question } } 

And the camera preview class:

 public class CameraPreviewNew extends ViewGroup implements Callback { public static final int CAMERA_BACK = 0; public static final int CAMERA_FRONT = 1; public Camera mCamera = null; private Context context = null; SurfaceView mSurfaceView; SurfaceHolder mSurfaceHolder; Size mPreviewSize; List<Size> mSupportedPreviewSizes; PreviewCallback mPreviewCallback; AutoFocusCallback mAutoFocusCallback; public CameraPreviewNew(Context context, PreviewCallback previewCallback, AutoFocusCallback autoFocusCb) { super(context); mPreviewCallback = previewCallback; mAutoFocusCallback = autoFocusCb; this.context = context; mSurfaceView = new SurfaceView(context); addView(mSurfaceView); mSurfaceHolder = mSurfaceView.getHolder(); mSurfaceHolder.addCallback(this); if (Build.VERSION.SDK_INT < Build.VERSION_CODES.HONEYCOMB) { mSurfaceHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS); } } public void setCamera(Camera camera) { mCamera = camera; if (mCamera != null) { mSupportedPreviewSizes = mCamera.getParameters() .getSupportedPreviewSizes(); requestLayout(); } } @Override protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { final int width = resolveSize(getSuggestedMinimumWidth(), widthMeasureSpec); final int height = resolveSize(getSuggestedMinimumHeight(), heightMeasureSpec); setMeasuredDimension(width, height); } public void hideSurfaceView() { mSurfaceView.setVisibility(View.INVISIBLE); } public void showSurfaceView() { mSurfaceView.setVisibility(View.VISIBLE); } public void surfaceCreated(SurfaceHolder holder) { try { if (mCamera != null) { mCamera.setPreviewDisplay(holder); } } catch (IOException exception) { Log.e("logtag", "IOException caused by setPreviewDisplay()", exception); } } public void surfaceDestroyed(SurfaceHolder holder) { if (mCamera != null) { mCamera.cancelAutoFocus(); mCamera.stopPreview(); } } public void surfaceChanged(SurfaceHolder holder, int format, int w, int h) { if (holder.getSurface() == null) { return; } if (mCamera != null) { Camera.Parameters parameters = mCamera.getParameters(); mPreviewSize = getBestPreviewSize(mCamera.getParameters(), w, h); parameters.setPreviewSize(mPreviewSize.width, mPreviewSize.height); requestLayout(); mCamera.setParameters(parameters); mCamera.setPreviewCallback(mPreviewCallback); mCamera.startPreview(); mCamera.autoFocus(mAutoFocusCallback); setCameraDisplayOrientation(0); } } private void setCameraDisplayOrientation(int cameraId) { Camera.CameraInfo info = new Camera.CameraInfo(); Camera.getCameraInfo(cameraId, info); int rotation = ((WindowManager) context .getSystemService(Context.WINDOW_SERVICE)).getDefaultDisplay() .getRotation(); int degrees = 0; switch (rotation) { case Surface.ROTATION_0: degrees = 0; break; case Surface.ROTATION_90: degrees = 90; break; case Surface.ROTATION_180: degrees = 180; break; case Surface.ROTATION_270: degrees = 270; break; } int result; if (info.facing == Camera.CameraInfo.CAMERA_FACING_FRONT) { result = (info.orientation + degrees) % 360; result = (360 - result) % 360; // compensate the mirror } else { // back-facing result = (info.orientation - degrees + 360) % 360; } mCamera.setDisplayOrientation(result); } protected static Comparator<Size> newSizeComparator() { return new Comparator<Size>() { @Override public int compare(Size lhs, Size rhs) { return Integer.valueOf(rhs.height * rhs.width).compareTo( lhs.height * lhs.width); } }; } private Size getBestPreviewSize(Parameters parameters, int screenWidth, int screenHeight) { List<Size> supportedSizes = parameters.getSupportedPreviewSizes(); Collections.sort(supportedSizes, newSizeComparator()); int previewHeight = screenHeight; int previewWidth = screenWidth; if (previewHeight > previewWidth) { int swap = previewWidth; previewWidth = previewHeight; previewHeight = swap; } Size bestSize = null; float bestRatio = 999; for (Size s : supportedSizes) { if (s.height > s.width) { int swap = s.width; s.width = s.height; s.height = swap; } float cameraRatio = ((float) s.height / (float) s.width); float screenRatio = ((float) previewHeight) / ((float) previewWidth); if ((s.height >= previewHeight) && (s.width >= previewWidth)) { float ratioDiff = cameraRatio - screenRatio; if ((ratioDiff < 0.19) && (ratioDiff > -0.19) && (Math.abs(bestRatio) > Math.abs(ratioDiff))) { bestSize = s; bestRatio = ratioDiff; } } } return bestSize; } public void setCameraFlashLight(Boolean setFlash) { Parameters _parameters = mCamera.getParameters(); if (setFlash) { _parameters.setFlashMode(Parameters.FLASH_MODE_TORCH); } else { _parameters.setFlashMode(Parameters.FLASH_MODE_OFF); } mCamera.setParameters(_parameters); mCamera.startPreview(); } @Override protected void onLayout(boolean changed, int l, int t, int r, int b) { if (changed && getChildCount() > 0) { final View child = getChildAt(0); final int width = r - l; final int height = b - t; int previewWidth = width; int previewHeight = height; if (mPreviewSize != null) { previewWidth = mPreviewSize.width; previewHeight = mPreviewSize.height; } if (width * previewHeight > height * previewWidth) { final int scaledChildWidth = previewWidth * height / previewHeight; child.layout((width - scaledChildWidth) / 2, 0, (width + scaledChildWidth) / 2, height); } else { final int scaledChildHeight = previewHeight * width / previewWidth; child.layout(0, (height - scaledChildHeight) / 2, width, (height + scaledChildHeight) / 2); } } } } 

Answer 1

I see some problems with your AutoFocus processing code.
Analysis result

There is a loop in your autofocus.

Explanation

a) The camera preview class mAutoFocusCallback set using autoFocusCb Camera Activity .

  public CameraPreviewNew(Context context,...,AutoFocusCallback autoFocusCb) { super(context); mAutoFocusCallback = autoFocusCb; ... } 

b) surfaceChanged is called once during activity loading. The camera requires autofocus.

  public void surfaceChanged(SurfaceHolder holder, int format, int w, int h) { if (mCamera != null) { ... mCamera.startPreview(); /*Auto focus camera and call <code>mAutoFocusCallback</code> after autofocus.*/ mCamera.autoFocus(mAutoFocusCallback); ... } } 

c) Upon completion of autofocus, the mAutoFocusCallback callback is called. mAutoFocusCallback->autoFocusCb->onAutoFocus()
Camera activity

  Camera.AutoFocusCallback autoFocusCB = new Camera.AutoFocusCallback() { public void onAutoFocus(boolean success, Camera camera) { mAutoFocusHandler.postDelayed(doAutoFocus, 1000); } }; 

d) onAutoFocus assigns another autofocus after 1000 milliseconds, 1 second.
Camera activity

  public void onAutoFocus(boolean success, Camera camera) { mAutoFocusHandler.postDelayed(doAutoFocus, 1000); } 

e) After one second, messages are sent to the handler, which calls the current doAutoFocus requesting camera for auto focus , similar to b) above.

  private Runnable doAutoFocus = new Runnable() { public void run() { if (mCamera != null && mPreviewing) { mCamera.autoFocus(autoFocusCB); } } }; 

f) After autofocus is autoFocusCb , autoFocusCb similar to c) is called again . and the cycle continues.

  Camera.AutoFocusCallback autoFocusCB = new Camera.AutoFocusCallback() { public void onAutoFocus(boolean success, Camera camera) { mAutoFocusHandler.postDelayed(doAutoFocus, 1000); } }; 

Decision

I am confused why such an implementation. This cycle may cause you to not listen to the flash on / off calls. You need to remove the code below and do something meaningful, otherwise leave onAutoFocus () empty.

 Camera.AutoFocusCallback autoFocusCB = new Camera.AutoFocusCallback() { public void onAutoFocus(boolean success, Camera camera) { /*REMOVE LINE BELOW*/ mAutoFocusHandler.postDelayed(doAutoFocus, 1000); } }; 

To automatically focus with each movement of the camera, you need to use the motion sensors that came with the phone. You can google it

Hope this helps. Happy coding ...

Answer 2

It seems you do not need to use AutoFocusCallBack for your application because you did nothing more than delay 1 second .

What can you do to focus all the time using FOCUS_MODE_CONTINUOUS_PICTURE (read here ), like this (the setFocus method is in CameraPreview , not in Activity ):

 public void setFocus() { Camera.Parameters p = mCamera.getParameters(); p.setFocusMode(Camera.Parameters.FOCUS_MODE_CONTINUOUS_PICTURE); mCamera.setParameters(p); mCamera.startPreview(); } 

And name it in SurfaceChanged :

 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.Parameters parameters = mCamera.getParameters(); List<Camera.Size> previewSizes = parameters.getSupportedPreviewSizes(); // You need to choose the most appropriate previewSize for your app Camera.Size previewSize = previewSizes.get(0); parameters.setPreviewSize(previewSize.width, previewSize.height); parameters.setRotation(90); mCamera.setParameters(parameters); mCamera.startPreview(); setFlash(true); setZoomLevel(5); setFocus(); Log.w(TAG, "surfaceChanged()"); } 

For flash you can use this method from CameraPreview :

 public void setFlash(boolean isFlashOn) { Camera.Parameters p = mCamera.getParameters(); if (isFlashOn) { p.setFlashMode(Camera.Parameters.FLASH_MODE_TORCH); mCamera.setParameters(p); mCamera.startPreview(); } else { p.setFlashMode(Camera.Parameters.FLASH_MODE_OFF); mCamera.setParameters(p); mCamera.startPreview(); } Log.w(TAG, "setFlash()"); } 

Hope this helps you! If you have any questions about my answer, feel free to comment.

Answer 3

Although it should be late if you switch camera settings, it is preferable to perform the sequence of operations as shown below

 mCamera.stopPreview(); mCamera.setParameters(params); // set flash on in Camera parameters mCamera.startPreview();