A even simpler paint program then paint.
void setup() {
background(255);
size(500,500);
println("Setup only once");
}
void mouseDragged(){
noFill();
ellipseMode(CENTER);
strokeWeight(2);
stroke(random(0,200));
float radius = random(1,10);
ellipse(mouseX,mouseY,radius,radius);
}
void draw() {
}
void keyPressed(){
if(key == 'c'){
noStroke();
fill(255);
rect(0,0,width,height);
}
if(key == 's'){
saveFrame("out.png");
}
}