`background()` method throws `NullPointerException` for `PGraphics` objects

[hx2A]

Most appropriate sub-area of Processing 4?

Core/Environment/Rendering

Processing version

4.5.2

Operating system

Linux (Unbuntu) and MacOS Tahoe

Bug description

I get a null pointer exception when I pass a PGraphics object to the background() method.

For some reason the PDE doesn't display the stack trace, I just see this:

NullPointerException
NullPointerException

Steps to reproduce this

The example code below reproduces the bug.

snippet

PGraphics g;

void setup() {
  size(300, 300, P3D);
  
  g = createGraphics(width, height, P2D);
  g.beginDraw();
  g.background(0, 255, 0);
  g.endDraw();
}

void draw() {
  background(g);
}

I am able to get a stack trace when I use the equivalent code in py5. I traced the problem to the PGraphics object's null pixels array.

One possible workaround is to insert a g.loadPixels() call after g.endDraw(). That fixes the problem. Another workaround is to get() a PImage object:

PGraphics g;
PImage img;

void setup() {
  size(300, 300, P3D);
  
  g = createGraphics(width, height, P2D);
  g.beginDraw();
  g.background(0, 255, 0);
  g.endDraw();
  img = g.get();
}

void draw() {
  background(img);
}

Additional context

Either workaround suggests a solution. I'm happy to make a PR to fix this, you can assign it to me.

Would you like to work on the issue?

Yes, I’d like to help with this