每次在特定区域单击鼠标时如何绘制矩形？

Question

I'm programming in Processing, and trying to get a rectangle to appear at the location of the mouse and stay there every time the mouse is clicked. However, when I run the program and click the mouse, the rectangle only stays for second, before it disappears. Is there another way to write it so that the rectangle isn't dependent on the mouse being clicked to exist?

Here is my code:

void setup()
{
   size(250, 350); 
}

void draw()
{
  background(255);
  fill(255);
  tileAp();
}

void tileAp()
{
  fill(0);
  if(mousePressed && mouseX <= 250 && mouseX >= 0 && mouseY >= 0 && mouseY <= 250)
  {

      drawM(true);
  }
  else
  {

  }
}     
void drawM(boolean b)
{
  if(b == true)
  {  
    rect(mouseX, mouseY, 25, 25);
  }
}   

Answer 1

You can stop calling background(255) in your draw method - this should allow the rectangles to stay.

Alternately, you can add each rectangle to a list, and then draw all of the rectangles every frame.