I'm not sure what you mean by before setup?

the logic to calculate the window size can be be within setup and the calcualtions can be done before setting the size.

1. void setup()
2. {
3.       int _width = getWidth();
4.       int _height = getHeight();
   
5.       size(_width, _height);
6. }
   

I am working with real world measurements, and so I need to be able to put in any size, from 6" to 72" in both dimensions, and it'll scale the window to fit my screen, but keep the aspect ratio. I got it to calculate scale factors and all that, and it has one scale factor to make the window fit my screen horizontally, and one vertically. I need to choose the lower scale factor and use that. Here's my code:

I guess you have that code before the setup. You need to move all your code (except variabel initialization) inside a method.

Yes, all that code is before the setup. The problem is that the scale variable is needed to determine the size of the window, which needs to be defined in setup. Essentially I want Z to equal the lower one of X and Y, and calculate that before the setup. You said I need to put it inside a method? I tried doing this, but the code inside scaleFactor never ran:

Java is not procedural, so just positioning code above the setup method does not mean it is run before setup.  Processing can be a bit confusing in this respect though as until you start adding methods it does behave as though it is procedural as everything gets wrapped up in a static method behind the scenes.

Once declared, setup becomes the entry point for the sketch and I don't believe it is possible to run anythign before this if using the Processing IDE. In eclipse this may be different as I you have access to the main method so can do some extra jiggery-pokery if you need to.

In any case, you should not need to run anything before setup as the size command does not need to be the first command within the method.

I think you may want something along these lines:

1. float scale;
   
2. 
   
3. void setup()
4. {
5.       scale = min(heightWindow/heightIn, widthWindow/widthIn);
6.       size(round(heightWindow * scale), round(widthWindow * scale));
   
7. }

I would advise against using scale as a variable name, as is also the name of a command. I would probably change this to _scale, but your naming convention is really your choice. 

Thank you so much. This is what I eventually used, and it's working great.