This is an idea of how you could do it. Don't forget to check the reference to understand the concept below. Note code below hasn't been tested.
Kf
//ASSUMING original image has a size of 500 in width
final int[] SIZES={450,550};
int dx=2;
void setup(){ ... }
void draw(){
//Next applies resize every 5 frames
if(frameCount%5==0){
resizeImage();
}
...
... OTHER draw functions
...
}
void resizeImage(){
int csize=img.width;
csize+=dx;
//NEXT: reverts direction of resizing when up/low limit is reached
if(csize<SIZES[0] || csize>SIZES[1] ){ //EDIT
dx=-dx;
}
img.resize(csize,0);
}
Answers
Look at PImage resize
look at random
This is an idea of how you could do it. Don't forget to check the reference to understand the concept below. Note code below hasn't been tested.
Kf
Why this sentence "sizes cannot be resolved to a variable" appears on the screen ?
It was untested code. I edited the post and fixed the problem.
Kf