LKB LKB - 5 months ago 55
Java Question

Android: Switch camera when button clicked

I have a method called switchCamera, I'm trying to switch camera from front to back on the click of a button, in one smooth transition. My application freezes when I call this method - I know I'm not doing something right. Can anyone help me out here?

Any help is much appreciated.

public void switchCamera(){
int camNum = 0;
camNum = Camera.getNumberOfCameras();
int camBackId = Camera.CameraInfo.CAMERA_FACING_BACK;
int camFrontId = Camera.CameraInfo.CAMERA_FACING_FRONT;

Camera.CameraInfo currentCamInfo = new Camera.CameraInfo();

//if camera is running
if (camera != null){
//and there is more than one camera
if (camNum > 1){
//stop current camera
camera.stopPreview();
camera.setPreviewCallback(null);
//camera.takePicture(null, null, PictureCallback);
camera.release();
camera = null;
//stop surfaceHolder?

if (currentCamInfo.facing == Camera.CameraInfo.CAMERA_FACING_FRONT){
//switch camera to back camera
camera=Camera.open(camBackId);
}
else{
//switch camera to front camera
camera=Camera.open(camFrontId);
}
//switch camera back on
//specify surface?
try {
camera.setPreviewDisplay(surfaceHolder);
camera.setPreviewCallback((PreviewCallback) this);
camera.startPreview();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
}

Answer
Button otherCamera = (Button) findViewById(R.id.OtherCamera);

OtherCamera.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
if (inPreview) {
    camera.stopPreview();
}
//NB: if you don't release the current camera before switching, you app will crash
camera.release();

//swap the id of the camera to be used
if(currentCameraId == Camera.CameraInfo.CAMERA_FACING_BACK){
    currentCameraId = Camera.CameraInfo.CAMERA_FACING_FRONT;
}
else {
    currentCameraId = Camera.CameraInfo.CAMERA_FACING_BACK;
}
camera = Camera.open(currentCameraId);

setCameraDisplayOrientation(CameraActivity.this, currentCameraId, camera);
try {

    camera.setPreviewDisplay(previewHolder);
} catch (IOException e) {
    e.printStackTrace();
}
camera.startPreview();
}

If you want to make the camera image show in the same orientation as the display, you can use the following code.

public static void setCameraDisplayOrientation(Activity activity,
         int cameraId, android.hardware.Camera camera) {
     android.hardware.Camera.CameraInfo info =
             new android.hardware.Camera.CameraInfo();
     android.hardware.Camera.getCameraInfo(cameraId, info);
     int rotation = activity.getWindowManager().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;
     }
     camera.setDisplayOrientation(result);
 }