Draw Rectangle which change size w.r.t different android screen size

I want to draw a rectangle using canvas which change its size with different screen size.

That means it increase of decrease its size with screen ratio.

I use the following code:

float scale = getContext().getResources().getDisplayMetrics().density;
canvas.drawRect(leftX-20*scale, leftY-20*scale, right开发者_开发百科X+20*scale, rightY, mPaint); 

But it does not change its size in different screen.

What can I do?

The problem is in getContext().getResources().getDisplayMetrics().density; it wil give you same dencity always better use the following approach

To get density Use the following code

DisplayMetrics metrics = new DisplayMetrics();    
getWindowManager().getDefaultDisplay().getMetrics(metrics);    
int screenDensity = metrics.densityDpi;

so your code will be

DisplayMetrics metrics = new DisplayMetrics();    
    getWindowManager().getDefaultDisplay().getMetrics(metrics);    
    float scale = metrics.densityDpi;

canvas.drawRect(leftX-20*scale, leftY-20*scale, rightX+20*scale, rightY, mPaint); 

Or you can try

float scale= Resources.getSystem().getDisplayMetrics().densityDpi;

This is implemented in my Android Game "MaracasRunner".