No idea. 
The routine I posted is super basic.
If you want to resize a 300x300 picture half the size you tell it to resize to 150x150 and you’re done.
However, if you tell it to resize to 100x150, it will return a 100x100 picture because it keeps the aspect ratio in tact.
If you want a more advanced and better quality resizer, check this routine from Beatrix: https://forum.xojo.com/34206-resize-images-gocomics-uses-xojo/p1#p279702