hello there

I am trying to write a program which can find random points within a given shape and then draw shapes to them. Eventually, this is with a view to creating print pieces so the final resolution will be quite high.

I have written the program below which uses a black and white .jpeg (in this case a letter A) as the shape template. The program identifies black pixels in the image, stores the X and Y co-ordinates to separate arrays which i then access randomly to find points.

It works fine but quite slowly at size(300, 300). bearing in mind i am eventually aiming to output 300dpi A3 images i was wondering whether there is a more efficient way to achieve the same result.

hope this makes sense.
thanks

1. PImage A;
   int[] xPos = new int[0];
   int[] yPos = new int[0];
   
   void setup() {
   
     size(300,300);
     A = loadImage("A.jpg");
     A.loadPixels();
     rectMode(CENTER);
     noLoop();
   
   }
   void draw() {
   
     for (int x= 0; x< A.width; x++) {
       for (int y = 0; y < A.height; y++) {
         if (A.pixels[(A.width*y)+x] == color(0,0,0)) {
           xPos = append(xPos, x);
           yPos = append(yPos, y);
         }
       }
     }
   
     for (int i = 0; i <200; i++) {
       int myNum = int(random(xPos.length));
       rect(xPos[myNum], yPos[myNum], 20, 20);
     }
   }