How to set processing to automatically detect an image size and set it as a background?

testnia

From my understanding, setting a background image in processing requires the size of the window to match the dimension of the image.

PImage img = loadImage("background.jpg"); //a 100x100 background image.
size(100,100);
background(img);

However, since size() does not take in variables, how are we suppose to define a background with variable dimensions?

I have tested with the surface.setSize() function but it does not see to work.

Example:

PImage img = loadImage("background.jpg"); //a 100x100 background image.
surface.setSize(img.width,img.height);
background(img);

GoToLoop

/**
 * Sized to PImage (v1.2)
 * by GoToLoop (2016-Sep-01)
 *
 * Forum.Processing.org/two/discussion/18033/
 * how-to-set-processing-to-automatically-detect-
 * an-image-size-and-set-it-as-a-background#Item_1
 */

static final String RENDERER = JAVA2D; // JAVA2D, FX2D, P2D, P3D, OPENGL

static final String HTTPS = "https://", SITE = "Processing.org/";
static final String FOLDER = "img/", FILE = "processing3-logo", EXT = ".png";
static final String PATH = HTTPS + SITE + FOLDER + FILE + EXT;

PImage bg;

void settings() {
  bg = loadImage(PATH);
  size(bg.width, bg.height, RENDERER);
  noLoop();
}

void draw() {
  background(bg);
}

testnia

It works! But doesn't the setting function gets called first? Is it due to delay that the setup function is able to read the size()?

GoToLoop

Yes, settings() is called even before setup(). Also needed for size() using variables as its arguments:
https://Processing.org/reference/settings_.html

I'm still using Processing v. 3.1.2. And so statement while (bg.width <= 1) delay(100); isn't needed here.

However, for newer versions, loadImage() is asynchronous by default, and doesn't block!
It means it can reach statement size(bg.width, bg.height); before the image is loaded & ready! :-SS

That's why I have that delay(); so it awaits width get bigger than 1. Meaning it's ready! ;;)

GoToLoop

On 2nd thought, I guess it is save() & saveFrame() function which are async, not loadImage()! b-(
Please disregard my explanation before. :-\". Gonna remove the delay() too, not needed! :P