keep the same aspect of preview with different resolutions

edit

I am doing an Android application with opencv, and i want that when the user changes the resolution, the preview image keep the size. Any ideas?

this is my java class which controls camera:

package com.example.telo3;

import java.util.List;


import org.opencv.android.JavaCameraView;
import org.opencv.android.NativeCameraView;

import android.content.Context;
import android.hardware.Camera.Size;
import android.util.AttributeSet;
import android.util.Log;

public class ControlCamera extends JavaCameraView {


    public ControlCamera(Context context, AttributeSet attrs) {
        super(context, attrs);

        mMaxWidth=176;
        mMaxHeight=144;
    }

    @SuppressWarnings("static-access")
    public int comprobar_camara() {

        return (mCamera.getNumberOfCameras());

    }

    public List<Size> getResolutionList() {
        return mCamera.getParameters().getSupportedPreviewSizes();
    }

    public void setResolution(Size resolution) {
        disconnectCamera();
        mMaxHeight = resolution.height;
        mMaxWidth = resolution.width;
        connectCamera(getWidth(), getHeight());

    }

    public Size getResolution() {
        return mCamera.getParameters().getPreviewSize();
    }

}

this my layout:

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    xmlns:opencv="http://schemas.android.com/apk/res-auto"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    tools:context=".MainActivity" >

    <com.example.telo3.ControlCamera
        android:id="@+id/tutorial5_activity_java_surface_view"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:visibility="gone"
        opencv:camera_id="front"
        opencv:show_fps="true" />

    <com.example.telo3.ControlCamera
        android:id="@+id/tutorial5_activity_java_surface_view2"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:visibility="gone"
        opencv:camera_id="back"
        opencv:show_fps="true" />

</RelativeLayout>

thanks