java - Android:单击按钮时切换相机

Question

我有一个名为 switchCamera 的方法，我试图通过单击一个按钮将相机从正面切换到背面，以平滑过渡。当我调用这个方法时，我的应用程序卡住了——我知道我做的不对。有谁能帮帮我吗？

非常感谢任何帮助。

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 1

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);
 }