gistfile1.pde

int MARGIN = 30,
  HEAD_SIZE = 200, // Jenkins, you bigheaded bastard
  DRUM_ROWS = 3,
  DRUM_COLS = 3,
  SPACING = 10;
  
ArrayList<DrumHead> drums = new ArrayList<DrumHead>();
ArrayList<PressArea> pressAreas = new ArrayList<PressArea>();

class PressArea {
  int top, left, bottom, right;
  ArrayList<PressArea> subAreas;
  
  boolean responsible(int x, int y) {
    return (x > left && x < right) && (y > top && y < bottom);
  }
  
  void delegate(int x, int y) {
    println("Delegated!");
    for (PressArea area : subAreas) {
      if (area.responsible(x, y)) {
        area.onPress(x, y);
      }
    }
  }
  
  void onPress(int x, int y) {
    return;
  }
}

class DrumHead extends PressArea {
  boolean active;
  
  DrumHead(int top, int left) {
    this.top = top;
    this.left = left;
    this.right = left + HEAD_SIZE;
    this.bottom = top + HEAD_SIZE;
  }
  
  void draw() {
    fill(this.active?100:200);
    rect(this.top, this.left, HEAD_SIZE, HEAD_SIZE, 10); 
  }
  
  void onPress(int x, int y) {
    println("Drum struck");
    this.active = true;
  }
}

class DrumsArea extends PressArea {
  DrumsArea() {
    this.bottom = height - MARGIN;
    this.top = this.bottom - DRUM_COLS * (HEAD_SIZE + SPACING);
    this.right = width - MARGIN;
    this.left = this.right - DRUM_ROWS * (HEAD_SIZE + SPACING);
    
    this.subAreas = new ArrayList<PressArea>();
    for (PressArea drum : drums) {
      this.subAreas.add(drum);
    }
  }
  
  void onPress(int x, int y) {
    println("DrumsArea onPress fired");
    this.delegate(x, y);
    println("DrumsArea onPress done");
  }
}

void setup() {
  background(0, 0, 0);
  
  DrumHead head;
  int x, y;
  for (int row = 0; row < DRUM_ROWS; row++) {
    for (int col = 0; col < DRUM_COLS; col++) {
      x = width - ((row + 1) * (HEAD_SIZE + SPACING)) - MARGIN;
      y = height - ((col + 1) * (HEAD_SIZE + SPACING)) - MARGIN;
      head = new DrumHead(x, y);
      drums.add(head);
    }
  }
  
  pressAreas.add(new DrumsArea());
}

void mousePressed() {
  println("press registered");
  println("X:" + mouseX + ", Y:" + mouseY);
  //for (PressArea area : pressAreas) {
  //  println("top level press delegation");
  //  area.onPress(mouseX, mouseY);
  //}
  println("top level press loop complete");
}

void draw() {
  for (DrumHead drum : drums) {
    drum.draw();
  }
}