python

maxSW = 12  # the thickest possible stroke weight
sz = 1    # variable to keep track of the current stroke weight

# set up the drawing area
def setup():
    size(400,400)
    background(200)

# define the draw function (always!)
def draw():
    pass  # do nothing

# when the mouse is dragged...
def mouseDragged():
    """ Draws lines on the screen.
        Slower strokes are fatter and faster ones are thinner. """
    global sz  # we will be changing the value of sz in this function, so make it global

    # how far did the mouse move? (minimum of one pixel)
    d = max(1, dist(pmouseX, pmouseY, mouseX, mouseY))

    # the stroke weight is a running average of current and previous stroke weight
    sz += maxSW/d
    sz /= 1.3
    strokeWeight( sz )

    # draw a line between the previous and current mouse positions
    line(pmouseX, pmouseY, mouseX, mouseY)

# when a key is pressed...
def keyPressed():
    """ when the delete key is pressed, clear the screen """
    print(keyCode)
    if( keyCode == 8):
        background(200)
    if(keyCode == 66):
        stroke(0,0,255)
    if(keyCode == 82):
        stroke(255, 10, 10)
    if(keyCode == 71):
        stroke(173,255,47)
    if(keyCode == 61):
        strokeWeight( sz )
    else:
        strokeWeight( sz - 2 )