put the Element on certain points on the background in a RelativeLayout

Question

I have an image, I want to put a TextView on a certain point(on the brown rectangle) in different devices with different screen sizes. My image is below:
CAUTION:the scaleType of the ImageView is CenterCrop

in image below I show where I want to put the TextView:

And this is my xml:

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    >
    <ImageView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:src="@drawable/startpage"<!-- my background-->
        android:scaleType="centerCrop"
        />

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="TextView"
        android:textColor="#fff"/>
</RelativeLayout>

Answer 1

At last, I found it myself, see these java codes:
I find the display width and height, then calculate the scale, the according to the scale I scale the margins.

@Bind(R.id.name_tv)TextView nameTV;

public final static float bgWidth = 768;
public final static float bgHeight = 1136;

public float tVsRightMargin = 123;
public float nameTVtopMargin = 314;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    ResourceManager.setActivity(this);
setContentView(R.layout.main);
ButterKnife.bind(this);

DisplayMetrics displayMetrics = new DisplayMetrics();
getWindowManager().getDefaultDisplay().getMetrics(displayMetrics);
int displayWidth = displayMetrics.widthPixels;
int displayHeight = displayMetrics.heightPixels;
Log.v("MainActivity","displayWidth: "+displayWidth);
Log.v("MainActivity", "displayHeight: " + displayHeight);

float scale = Math.max(displayWidth/bgWidth, displayHeight/bgHeight);
Log.v("MainActivity", "scale: "+scale);

float bgScaledWidth = scale*bgWidth;
float bgScaledHeight = scale*bgHeight;

tVsRightMargin *= scale;
nameTVtopMargin *= scale;

if(bgScaledWidth>displayWidth) {
    tVsRightMargin -= ((bgScaledWidth - displayWidth) / 2f);
}
if(bgScaledHeight>displayHeight){
    nameTVtopMargin -= ((bgScaledHeight-displayHeight)/2f);
}

nameTV.setText("محمد");
nameTV.setTypeface(ResourceManager.getTypeface());


Log.v("MainActivity", "top margin: " + nameTVtopMargin);
Log.v("MainActivity", "right margin: " + tVsRightMargin);
((RelativeLayout.LayoutParams) nameTV.getLayoutParams()).setMargins(0, (int) nameTVtopMargin, (int) tVsRightMargin, 0);

}