Mirroring an Image by its Diagonal in Jython

Question

So I need to mirror an image. The top right side of the image should be flipped over to the bottom left side. I created a function that flips the top left side of an image to the bottom right, but I just can't seem to figure out how to do it the other way. Here's the code:

def mirrorPicture(picture):
 height = getHeight(canvas)
 width = height 

 # to make mirroring easier, let us make it a square with odd number 
 # of rows and columns
 if (height % 2 == 0):
    height =  width = height -1  # let us make the height and width odd


 maxHeight = height - 1
 maxWidth  = width - 1

 for y in range(0, maxWidth):
      for x in range(0, maxHeight - y):     
      sourcePixel = getPixel(canvas, x, y)
      targetPixel = getPixel(canvas, maxWidth - y, maxWidth - x)
      color = getColor(sourcePixel)
      setColor(targetPixel, color)

 return canvas

btw, i'm using an IDE called "JES".

You are not doing a proper flip in the posted code either: you need to *exchange* the colors of sourcePixel and targetPixel. For your question, think about it this way: as posted, your program copies (x,y) to (max-y,max-x). Draw a diagram if needed: which pixels must be copied where to flip it along the other diagonal? — Armin Rigo, Jun 14 '13 at 11:14

score 2 · Answer 1 · edited May 23 '17 at 12:07

If by "mirroring", you meant "flip diagonally", this should work :

def mirrorPicture(picture):
    height = getHeight(picture)
    width = getWidth(picture)

    newPicture = makeEmptyPicture(height, width)

    for x in range(0, width):   
        for y in range(0, height):
            sourcePixel = getPixel(picture, x, y)

            targetPixel = getPixel(newPicture, y, x)
            #                                  ^^^^  (simply invert x and y)
            color = getColor(sourcePixel)
            setColor(targetPixel, color)

    return newPicture

Giving :

.................. enter image description here ...............................................

Related answer about mirroring diagonally here.

Mirroring an Image by its Diagonal in Jython

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