Assignment 27 — coloring within the lines

Due Thursday April 26

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Module crayon.py

• Complete the implementation of the functions flood() and sweep(). It uses usa.py to test flood() and sweep()

• Two other testers for sweep() are available

• uva.py

• book.py

• The two functions should make use of do.py to do all coloring. A correct version of do.py will be available after it is due.

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Flooding visualization

• Slides

• Slides exported as PDF

• Slides exported as MP4

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Function flood( drawing, spot, c, bg=(255,255,255) )

• If spot is not a colorable pixel on drawing, then no action is taken.

• If instead spot is a colorable pixel on drawing, then all pixel locactions reachable from spot traversing only colorable pixels are set to color c.

• The function does not return a value

• Visualization of how flood() should work is available above.

• (Highly) recommended algorithm

 If the spot on the drawing is not empty

  return

 Color the spot using c

 Create a to-do list with spot as its element

 While the to-do list is not empty

  Pop an element from the to-do list and assign it to v

  If v’s left is empty, paint it and add to to-do list

  If v’s right is empty, paint it and add to to-do list

  If v’s above is empty, paint it and add to to-do list

  If v’s below is empty, paint it and add to to-do list

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Function sweep( drawing, bg=(255,255,255) )

• For every bg colorable drawing pixel, a flood() is performed. For each flooding a new random color is used.

• The function does not return a value.

• My implementation considers the rows of pixels making up a picture from top to bottom. Within a row, the pixels were considered left to right. If you do a different order, your picture could look different. Also, my implementation only generates a random color only if the pixel under consideration is colorable.

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Coloring examples

       

       

       

       

       

       

       

 

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