Click on one of the colored squares in the center of the image to change the color of the background.
Original Processing.org Example: Button
// All Examples Written by Casey Reas and Ben Fry // unless otherwise stated. int rectX, rectY; // Position of square button int circleX, circleY; // Position of circle button int rectSize = 50; // Diameter of rect int circleSize = 53; // Diameter of circle color rectColor, circleColor, baseColor; color rectHighlight, circleHighlight; color currentColor; boolean rectOver = false; boolean circleOver = false; void setup() { size(200, 200); smooth(); rectColor = color(0); rectHighlight = color(51); circleColor = color(255); circleHighlight = color(204); baseColor = color(102); currentColor = baseColor; circleX = width/2+circleSize/2+10; circleY = height/2; rectX = width/2-rectSize-10; rectY = height/2-rectSize/2; ellipseMode(CENTER); } void draw() { update(mouseX, mouseY); background(currentColor); if(rectOver) { fill(rectHighlight); } else { fill(rectColor); } stroke(255); rect(rectX, rectY, rectSize, rectSize); if(circleOver) { fill(circleHighlight); } else { fill(circleColor); } stroke(0); ellipse(circleX, circleY, circleSize, circleSize); } void update(int x, int y) { if( overCircle(circleX, circleY, circleSize) ) { circleOver = true; rectOver = false; } else if ( overRect(rectX, rectY, rectSize, rectSize) ) { rectOver = true; circleOver = false; } else { circleOver = rectOver = false; } } void mousePressed() { if(circleOver) { currentColor = circleColor; } if(rectOver) { currentColor = rectColor; } } boolean overRect(int x, int y, int width, int height) { if (mouseX >= x && mouseX <= x+width && mouseY >= y && mouseY <= y+height) { return true; } else { return false; } } boolean overCircle(int x, int y, int diameter) { float disX = x - mouseX; float disY = y - mouseY; if(sqrt(sq(disX) + sq(disY)) < diameter/2 ) { return true; } else { return false; } }