Looking for more resources about ArrayLists

Processing Beginners
30

Remark

sub = new ArrayList <SubGrid>(); //

this deletes the whole thing

Remark

without background (255); at start of draw() you see the accumulated results of all drawings.

You can’t really see what the last mousePressed did!

Remark

I think this doesn’t do what you want:

    rect (x, y, w/2, h/2);
    rect (x, y/2, w/2, h/2);
    rect (x/2, y, w/2, h/2);
    rect (x/2, y/2, w/2, h/2);

for example, the rects are called with

0.0 0.0
100.0 0.0
200.0 0.0
300.0 0.0
400.0 0.0
500.0 0.0
600.0 0.0
700.0 0.0
800.0 0.0

in the first round.

but e.g. this line rect (x/2, y, w/2, h/2); results in

   rect (0, 0, w/2, h/2);
   rect (50, 0, w/2, h/2);
   rect (100, 0, w/2, h/2);
   rect (150, 0, w/2, h/2);

so it’s far more left than the initial rect (x, y, w/2, h/2);

That’s why you see the gaps on the right.

Here is my version of the code section (one cell is divided into four cells):

    fill( 255, 0, 0 );
    rect (x, y, w/2, h/2);
    fill( 0, 255, 0);
    rect (x, y+h/2, w/2, h/2);
    fill( 0, 0, 255);
    rect (x+w/2, y, w/2, h/2);
    fill( 255, 0, 255);
    rect (x+w/2, y+h/2, w/2, h/2);

Full Sketch

Full Sketch to demonstrate some of the above

ArrayList <GridCell> grid;
ArrayList <SubGrid> sub;
float w;
float yNew = 0;

void setup() {
  size (800, 400);
  background (255);

  grid = new ArrayList <GridCell>();
  sub = new ArrayList <SubGrid>();

  w = width/8; 
  float h = height;

  for (float x = 0; x <= width; x+=w) {
    grid.add(new GridCell(x, 0, 
      w, h-=9));
  }
}

void draw() {
  background (255);

  //float h = width/8;

  for (int i = 0; i < grid.size(); i++) { // can use short form of for-loop here
    grid.get(i).display();
  }  

  for (int j = 0; j < sub.size(); j++) {// can use short form of for-loop here
    sub.get(j).display();
  }
}

//---------------------------------------------------------------------------------

void mousePressed() {

  sub = new ArrayList <SubGrid>(); // this deletes the whole thing 

  float w = width/8;
  float h = w;

  for (int i = 0; i < grid.size(); i++) {
    if (mouseX>grid.get(i).x&&
      mouseX<grid.get(i).x+w ) {
      sub.add(new SubGrid(grid.get(i).x, yNew, w, h));
    }
  }

  yNew = yNew+55;
}

//MAIN GRID CLASS //////////////////////////////////

class GridCell {
  float x, y;
  float w, h;

  GridCell(float x_, float y_, 
    float w_, float h_) {
    x = x_;
    y = y_;
    w = w_;
    h = h_;
  }

  void display() {
    stroke(0);
    noFill();
    rect (x, y, 
      w, h);
  }
}//class 

//SUBGRID CLASS //////////////////////////////

class SubGrid {

  float x, y;
  float w, h;
  color col1 = color(random(255), random(255), random(255), 50); // set random color at the start of the class, so we don't have a flickering color
  color col2 = color(random(255), random(255), random(255), 50); // set random color at the start of the class, so we don't have a flickering color

  SubGrid(float x_, float y_, 
    float w_, float h_) {
    x = x_;
    y = y_;
    w = w_;
    h = h_;
  }

  void display() {
    stroke(0);
    fill( 255, 0, 0 );
    rect (x, y, w/2, h/2);
    fill( 0, 255, 0);
    rect (x, y+h/2, w/2, h/2);
    fill( 0, 0, 255);
    rect (x+w/2, y, w/2, h/2);
    fill( 255, 0, 255);
    rect (x+w/2, y+h/2, w/2, h/2);
  }
}//class
//

Chrisir

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