android - Cannot resolve method getSystemService issue

Question

I'm experiencing the problem concerning getSystemService method, as the Android Studio IDE keeps telling me it just cannot resolve this method. As far as I've read it might come out from the fact, that my class doesn't contain activity. I was reading related topics about getSystemService issue, but I couldn't find any matching solution at all.

I place my code above

import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Matrix;
import android.graphics.Rect;
import android.hardware.Camera;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.TextView;

public class MainActivity extends AppCompatActivity {

private Camera mCamera;
private CameraView mCameraView;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
}


@Override
protected void onResume(){
    super.onResume();

    try{
        mCamera = Camera.open(1);
        mCameraView = new CameraView(this, mCamera);
        setContentView(mCameraView);
    } catch (Exception e){
        finish();
    }
}

@Override
protected void onPause(){
    if(mCamera != null){
        mCamera.release();
        mCamera = null;
    }
    super.onPause();


   }

}

The bold one of the class above is the one I'm trying to figure out

import android.content.Context;
import android.hardware.Camera;
import android.hardware.Camera.Parameters;
import android.util.Log;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.View;
import android.view.Surface;
import android.view.Display;
import android.view.WindowManager;
import java.io.IOException;
import android.app.Activity;
import java.util.List;


public class CameraView extends SurfaceView implements SurfaceHolder.Callback{


private Camera mCamera;
private View mView;
private WindowManager display;


public CameraView(Context context, Camera mCamera) {
    super(context);

    this.mCamera = mCamera;
    mCamera.setDisplayOrientation(90);

    SurfaceHolder holder = getHolder();
    holder.addCallback(this);
    holder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);

}


@Override
public void surfaceCreated(SurfaceHolder holder) {
    try{
        mCamera.setPreviewDisplay(holder);
        mCamera.startPreview();
    } catch (IOException e) {
        Log.e("cameraPreview", "The failure of the camera settings");
    }
}


@Override
public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
    Camera.Parameters params = mCamera.getParameters();
    List<Camera.Size> sizes = params.getSupportedPreviewSizes();
    Camera.Size optionalSize = getOptimalPreviewSize(sizes, width, height);
    params.setPreviewSize(optionalSize.width, optionalSize.height);
    mCamera.setParameters(params);

    boolean isPreviewRunning = true;

    if (isPreviewRunning)
    {
        mCamera.stopPreview();
    }

    Parameters parameters = mCamera.getParameters();
    Display display = ((WindowManager) getSystemService(Context.WINDOW_SERVICE)).getDefaultDisplay();  

    if(display.getRotation() == Surface.ROTATION_0)
    {
        parameters.setPreviewSize(height, width);
        mCamera.setDisplayOrientation(90);
    }

    if(display.getRotation() == Surface.ROTATION_90)
    {
        parameters.setPreviewSize(width, height);
    }

    if(display.getRotation() == Surface.ROTATION_180)
    {
        parameters.setPreviewSize(height, width);
    }

    if(display.getRotation() == Surface.ROTATION_270)
    {
        parameters.setPreviewSize(width, height);
        mCamera.setDisplayOrientation(180);
    }

    mCamera.setParameters(parameters);
    previewCamera();
}

public void previewCamera()
{
    try
    {
        mCamera.setPreviewDisplay();
        mCamera.startPreview();
        boolean isPreviewRunning = true;
    }
    catch(Exception e)
    {
        Log.d(APP_CLASS, "Cannot start preview", e);
    }
}

@Override
public void surfaceDestroyed(SurfaceHolder holder) {
    mCamera.release();
    mCamera = null;
}

private Camera.Size getOptimalPreviewSize(List<Camera.Size> sizes, int w, int h) {

    final double ASPECT_TOLERANCE = 0.1;
    double targetRatio=(double)h / w;

    if (sizes == null) return null;

    Camera.Size optimalSize = null;
    double minDiff = Double.MAX_VALUE;

    int targetHeight = h;

    for (Camera.Size size : sizes) {
        double ratio = (double) size.width / size.height;
        if (Math.abs(ratio - targetRatio) > ASPECT_TOLERANCE) continue;
        if (Math.abs(size.height - targetHeight) < minDiff) {
            optimalSize = size;
            minDiff = Math.abs(size.height - targetHeight);
        }
    }

    if (optimalSize == null) {
        minDiff = Double.MAX_VALUE;
        for (Camera.Size size : sizes) {
            if (Math.abs(size.height - targetHeight) < minDiff) {
                optimalSize = size;
                minDiff = Math.abs(size.height - targetHeight);
            }
        }
    }
    return optimalSize;


  }



}

Could You possibly tell me how it should be done to avoid this matter?

Thanks!

Answer 1

You need to call getSystemService on a Context, hence, why it doesn't work in your CameraView. You can store the context you already pass in as a field and call getSystemService on that. See your modified code below:

import android.content.Context;
import android.hardware.Camera;
import android.hardware.Camera.Parameters;
import android.util.Log;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.View;
import android.view.Surface;
import android.view.Display;
import android.view.WindowManager;
import java.io.IOException;
import android.app.Activity;
import java.util.List;


public class CameraView extends SurfaceView implements SurfaceHolder.Callback{


private Camera mCamera;
private View mView;
private WindowManager display;
private Context mContext;


public CameraView(Context context, Camera mCamera) {
    super(context);

    mContext = context;

    this.mCamera = mCamera;
    mCamera.setDisplayOrientation(90);

    SurfaceHolder holder = getHolder();
    holder.addCallback(this);
    holder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);

}


@Override
public void surfaceCreated(SurfaceHolder holder) {
    try{
        mCamera.setPreviewDisplay(holder);
        mCamera.startPreview();
    } catch (IOException e) {
        Log.e("cameraPreview", "The failure of the camera settings");
    }
}


@Override
public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
    Camera.Parameters params = mCamera.getParameters();
    List<Camera.Size> sizes = params.getSupportedPreviewSizes();
    Camera.Size optionalSize = getOptimalPreviewSize(sizes, width, height);
    params.setPreviewSize(optionalSize.width, optionalSize.height);
    mCamera.setParameters(params);

    boolean isPreviewRunning = true;

    if (isPreviewRunning)
    {
        mCamera.stopPreview();
    }

    Parameters parameters = mCamera.getParameters();
    Display display = ((WindowManager) mContext.getSystemService(Context.WINDOW_SERVICE)).getDefaultDisplay();  

    if(display.getRotation() == Surface.ROTATION_0)
    {
        parameters.setPreviewSize(height, width);
        mCamera.setDisplayOrientation(90);
    }

    if(display.getRotation() == Surface.ROTATION_90)
    {
        parameters.setPreviewSize(width, height);
    }

    if(display.getRotation() == Surface.ROTATION_180)
    {
        parameters.setPreviewSize(height, width);
    }

    if(display.getRotation() == Surface.ROTATION_270)
    {
        parameters.setPreviewSize(width, height);
        mCamera.setDisplayOrientation(180);
    }

    mCamera.setParameters(parameters);
    previewCamera();
}

public void previewCamera()
{
    try
    {
        mCamera.setPreviewDisplay();
        mCamera.startPreview();
        boolean isPreviewRunning = true;
    }
    catch(Exception e)
    {
        Log.d(APP_CLASS, "Cannot start preview", e);
    }
}

@Override
public void surfaceDestroyed(SurfaceHolder holder) {
    mCamera.release();
    mCamera = null;
}

private Camera.Size getOptimalPreviewSize(List<Camera.Size> sizes, int w, int h) {

    final double ASPECT_TOLERANCE = 0.1;
    double targetRatio=(double)h / w;

    if (sizes == null) return null;

    Camera.Size optimalSize = null;
    double minDiff = Double.MAX_VALUE;

    int targetHeight = h;

    for (Camera.Size size : sizes) {
        double ratio = (double) size.width / size.height;
        if (Math.abs(ratio - targetRatio) > ASPECT_TOLERANCE) continue;
        if (Math.abs(size.height - targetHeight) < minDiff) {
            optimalSize = size;
            minDiff = Math.abs(size.height - targetHeight);
        }
    }

    if (optimalSize == null) {
        minDiff = Double.MAX_VALUE;
        for (Camera.Size size : sizes) {
            if (Math.abs(size.height - targetHeight) < minDiff) {
                optimalSize = size;
                minDiff = Math.abs(size.height - targetHeight);
            }
        }
    }
    return optimalSize;


  }