1. Creative Commons Attribution Non-Commercial Share Alike License
Original Developer: Beth Simon, 2009

2. CSE8A Lecture 10 Read next class: read pg 142-152 PSA3 HINT: Collage
You should then create a picture that is the same height as the one you chose, but three times as wide.
Picture foo = new Picture (100, 300);
Turtle jose = new Turtle (25, 50, w);

3. By the end of today’s class you should be able to…
LG22: Read and code nested loops to perform mirroring (and related) transformations using nested loops.

4. Nested Loops: How do they work? What order are pixels changed?
DON’T REVEAL, VOTING
OR DISCUSS ISOMORPHIC QUESTION NEXT
Nested Loops: How do they work? What order are pixels changed?
A method in Picture.java…
Pixel p;
for (int foo = 0; foo < getWidth(); foo++) {
for (int bar 0; bar < getHeight(); bar++)
p = getPixel(foo, bar);
p.setColor(Color.BLACK); }

5. Nested Loops: How do they work? What order are pixels changed?
A method in Picture.java…
Pixel p;
for (int bar = 0; bar < getHeight(); bar++) {
for (int foo = 0; foo < getWidth(); foo++)
p = getPixel(foo, bar);
p.setColor(Color.BLACK); }

6. What do these methods do? What are their return values?
getPixel(int x, int y)
getHeight()
getWidth()

7. Why does this have an error?
A method in Picture.java…
Pixel p;
for (int bar = 0; bar < getWidth(); bar++) {
for (int foo = 0; foo < getHeight(); foo++)
p = getPixel(foo, bar);
p.setColor(Color.BLACK); }
It doesn’t, this loops across rows, going down
It doesn’t, this loops down columns, going right
It tries to index a pixel off the end of a row (foo value too big)
It tries to index a pixel off the end of a column (bar value too big)