How to Position Shape based on display size

Processing Coding Questions
3

Thanks Sir.
</
static int x=0;

void setup()
{
size(displayWidth, displayHeight);
frameRate(20);
}

void draw()
{
background(0);
ellipse(x++, 100, 5,5);
text(x, 200, 400);
}>

I used the above code, could confirm the screen origin (0,0) is top left. and the screen is 1600x900.
but still not able to get location precision.
I am adopting to use the display resolution incase a different screen will be use to run the application.