pixel screensaver sketch with flame effects

MainApp.java

import processing.core.PApplet;
import processing.core.PImage;
import java.awt.*;
  
  PImage orig;
  int scaledown = 1;
  public void settings()
  {
      fullScreen();
      orig = screenshot();

  }

  public void setup(){
      imageMode(CENTER);
      image(orig, width/2, height/2,orig.width/scaledown, orig.height/scaledown);
  }

  public void draw()
  {
      loadPixels();
      modifyPixels();
      updatePixels();
  }
  
  

  private void modifyPixels(){
      for(int y = 0; y < height-1; y++) {
          for(int x = 0; x < width-1; x++){
              if(getPixel(x, y) > getPixel(x+1, y)){
                  swapPixels(x, y, x, y+1);
              }
          }
      }
  }

  private int getPixel(int x, int y){
      int oneDim = x + y * width;
      if(oneDim < pixels.length){
          return pixels[oneDim];
      }
      return color(255);
  }

  private void setPixel(int x, int y, int clr){
      int oneDim = x + y * width;
      if(oneDim<pixels.length){
          pixels[x + y * width] = clr;
      }
  }

  private void swapPixels(int x0, int y0, int x1, int y1){
      int a = getPixel(x0, y0);
      int b = getPixel(x1, y1);
      setPixel(x0, y0, b);
      setPixel(x1, y1, a);
  }

  private PImage screenshot() {
      PImage screenshot = null;
      try {
          screenshot = new PImage(new Robot().createScreenCapture(new Rectangle(0, 0, displayWidth, displayHeight)));
      } catch (AWTException e) {
          e.printStackTrace();
      }
      return screenshot;
  }