Python, part 10

More animation.
We'll first create a large circle on the canvas which rapid shrinks in
size. We'll assume the canvas has fill sky blue, or something other
than orange.

    oldx = 0                     coordinates will always be (oldx,oldx) and
    oldx2 = 400               (oldx2,oldx2) so we have a circle.

    while oldx <= 190:        continue until we're almost at the center

            myCanvas.create_oval(oldx,oldx,oldx2,oldx2,fill="orange",\
                            outline="orange")
            myCanvas.pack()
            myCanvas.update()
            time.sleep(0.1)           0.3 etc to shrink the circle slower
            myCanvas.create_oval(oldx,oldx,oldx2,oldx2,fill="orange",\
                            outline="orange")
            oldx = oldx + 5
            oldx2 = oldx2 - 5       the upper left-hand corner of the square
                                                moves in and down, the lower right-hand
                                                corner moves left and up.....you can also have
                                                smaller (or larger) increments here.

                                                          pulsar

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Optional exercise: have the circle pulse in and out 5 times--i.e. starts
large, shrinks to nothing, swells larger and larger, shrinks, etc. To do
this--we need an outer for loop that loops 5 times: for i in range(5).
Inside the for loop we have the code above to shrink the circle. Then
we have a second while loop to expand the circle--
       oldx = 190
       oldx2 = 210
       while oldx >= 0:

          then we'll have oldx = oldx -5 and oldx2 = oldx2 + 5

Variation: at maximum size, perhaps print text that says "BOOM!"
at the center of the circle.
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MEASLES
We'll create different-colored spots at random on a white canvas.
Make Canvas white (or whatever).

    for i in range(200):        for 200 spots
          xpt = random.randrange(1,390)
          ypt = random.randrange(1,390)     random x-y coordinates
          randcol = random.randrange(1,7)
          if randcol == 1:
                   mycolor = "red"              as shown in a previous page--
          elif randcolor == 2:                   we'll pick a color at random
                   mycolor = "purple"
          elif randcolor == 3:
                   mycolor = "green"
          elif randcolor == 4:
                   mycolor = "blue"
          elif randcolor == 5:
                   mycolor = "orange"
          else:
                   mycolor = "brown"
    myCanvas.create_oval(xpt,ypt,xpt+8,ypt+8,fill=mycolor)
                                 for smaller spots, xpt + 5, etc
    myCanvas.pack()
    myCanvas.update()
    time.sleep(0.1)
                                                     measles

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