2019_Schafkopfzaehler/app/src/main/java/project/schafkopfzaehler_2/cameraPreview.java

package project.schafkopfzaehler_2;

import android.content.Context;
import android.hardware.Camera;
import android.util.Log;
import android.util.Size;
import android.view.SurfaceHolder;
import android.view.SurfaceView;

import java.io.IOException;
import java.util.List;

/** A basic Camera preview class */
public class cameraPreview extends SurfaceView implements SurfaceHolder.Callback {
    private SurfaceHolder mHolder;
    private Camera mCamera;

    public cameraPreview(Context context, Camera camera) {
        super(context);
        mCamera = camera;

        // Install a SurfaceHolder.Callback so we get notified when the
        // underlying surface is created and destroyed.
        mHolder = getHolder();
        mHolder.addCallback(this);

    }

    public void surfaceCreated(SurfaceHolder holder) {
        // The Surface created, now tell the camera where to draw the preview.
        try {
            mCamera.setPreviewDisplay(holder);
            mCamera.startPreview();
        } catch (IOException e) {
            Log.d("CAMERA", "Error setting camera preview: " + e.getMessage());
        }
    }

    public void surfaceDestroyed(SurfaceHolder holder) {
        // empty. Take care of releasing the Camera preview in your activity.
    }

    public void surfaceChanged(SurfaceHolder holder, int format, int w, int h) {
        // If your preview can change or rotate, take care of those events here.
        // Make sure to stop the preview before resizing or reformatting it.

        if (mHolder.getSurface() == null){
            // preview surface does not exist
            return;
        }

        if (mHolder == null){
            // holder does not exist
            return;
        }

        // Stop preview before making changes
        try {
            mCamera.stopPreview();
        } catch (Exception e){
            // ignore: tried to stop a non-existent preview
        }

        mCamera.setDisplayOrientation(90);

        // Get lowest possible resolution to minimize data traffic
        Camera.Parameters setting_param = mCamera.getParameters();
        List<Camera.Size> sizes = setting_param.getSupportedPictureSizes();
        int height;
        int width;
        for (Camera.Size size : sizes) {
            width = size.width;
            height = size.height;

            if (width >= 600 && width <= 800) {
                setting_param.setPictureSize(width, height);
                break;
            }
        }

        mCamera.setParameters(setting_param);

        // Start preview with new resolution
        try {
            mCamera.setPreviewDisplay(mHolder);
            mCamera.startPreview();

        } catch (Exception e){
            Log.d("CAMERA", "Error starting camera preview: " + e.getMessage());
        }
    }
}