Copying PGraphics to PImage using .get() or .copy() clears PGraphics object, if the renderer is P2D

Created by: agrshch

Description

An attempt of copying information from PGraphics to PImage using get() or copy() clears the PGraphics object if P2D renderer is used. It makes impossible many things, for example using PGraphics (or its copy) as a texture for the shader.

Expected Behavior

successful copying, like with default renderer

Current Behavior

both PGraphics and PImage are empty.

Steps to Reproduce

PGraphics img1;

void setup() {
size(300, 300, P2D);

img1 = createGraphics(200, 200, P2D);

img1.beginDraw();
img1.background(120);
img1.endDraw();

PImage img2 = img1.get(); // if comment out this line — grey rectangle appears
}

void draw() {
background(255);
image(img1, 100, 20);
}

Your Environment

• Processing version: 4.2
• Operating System and OS version: Mac OS 10.15.7
• Other information:

Start by running the provided P2D sketch and tracing the PGraphics get() and copy() entry points in the Java core library. Compare the P2D behavior with the default renderer, checking why the source and destination become empty. Done means copying preserves the PGraphics contents and produces a populated PImage under P2D.