CS 1112

Class 40 — November 29

Color within the lines

Look both ways

Back or ahead

Agenda

Create library to paint coloring book pages by implementating HW 28 module crayon functions flood() and sweep().

Selfie

self-portrait

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.

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

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.

Note, 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.