I'm using a PGraphics2D, pg, as my own backbuffer. My PApplet is added to a class extending JPanel. To handle resizing the PApplet and the images contained in it, I added a ComponentListener to my JPanel. componentResized() sets the size() of the PApplet and calls a method to redraw some stuff then when all of that is done, we go to my method to update the whole backbuffer before draw() gets a hold of anything. Occasionally I will get an ArrayIndexOutOFBoundsException looking like this.

Code:

Exception in thread "AWT-EventQueue-0" java.lang.ArrayIndexOutOfBoundsException: -1
        at processing.core.PPolygon.coverage(PPolygon.java:606)
        at processing.core.PPolygon.scanline(PPolygon.java:526)
        at processing.core.PPolygon.render(PPolygon.java:335)
        at processing.core.PGraphics2D.endShape(PGraphics2D.java:401)
        at processing.core.PGraphics.endShape(PGraphics.java:1153)
        at processing.core.PGraphics.imageImpl(PGraphics.java:2293)
        at processing.core.PGraphics2D.imageImpl(PGraphics2D.java:1410)
        at processing.core.PGraphics.image(PGraphics.java:2221)
        at processing.core.PGraphics.image(PGraphics.java:2197)
 

followed by a reference to a line in my code where I am simply adding an image that already exists and was not altered in the process, aside from being resize by the image(x,y,wid,hight) method. I'm stumped. I will also occasionally get a null pointer exception when I resize. . .

Heres the spot where the Exception is happening (keep in mind that this Exception happens during one of the image() calls, these images should already be set):

Code:

 private void updateScreenImage() {
        //Draw to BackBuffer, you don't want to see that rescaling happen
        //long startTime = System.currentTimeMillis();
        pg.beginDraw();
        pg.background(BACKGROUND_COLOR);
        pg.smooth();
        pg.stroke(100);//GRID_TEXT_COLOR);
        pg.image(bgrnd.get(), OFFSET, OFFSET, width-OFFSET-5, height-OFFSET-5);
        pg.image(hist.get(), OFFSET, OFFSET, width-OFFSET-5, height-OFFSET-5);
        pg.image(grid.get(), OFFSET-5, OFFSET, grid.width, grid.height);
        pg.image(vertLabel.get(),0,0,vertLabel.width, vertLabel.height);
        pg.image(titleLabel.get(),OFFSET,5,titleLabel.width,titleLabel.height);
        pg.noFill();
        pg.rect(OFFSET-1, OFFSET-1, width-OFFSET-4, height-OFFSET-4);

        pg.endDraw(); 

and here's my componentResized() method:
Code:

if(this.isShowing()){
            histogram.noLoop();
            ((ProcessingHistogram)histogram).resetGrid(this.getWidth() - 1, this.getHeight() - 1);
            histogram.loop();

            resizedWhileHidden = false;
        } 

and finally, here is my resetGrid() method, All I'm really doing here, is redrawing to a couple Pgraphics2D buffers and redrawing a line grid, to overlay my graph just so it doesn't get stretched in a resize:
Code:

public void resetGrid(int wid, int hig){
        size(wid, hig); //reset size first

        titleLabel = new PGraphics2D();
        titleLabel.setParent(this);
        titleLabel.setPrimary(false);
        titleLabel.setSize(width-OFFSET-5, OFFSET-10);
        titleLabel.beginDraw();
        titleLabel.background(BACKGROUND_COLOR);
        titleLabel.image(miniHuey,(int)(titleLabel.width-miniHuey.width)-5,2);
        titleLabel.stroke(50);
        titleLabel.noFill();
        titleLabel.rect((float)(titleLabel.width-miniHuey.width)-5,2,miniHuey.width,miniHuey.height);
        titleLabel.textFont(TITLE_TEXT_FONT);
        titleLabel.fill(GRID_TEXT_COLOR);
        titleLabel.text("HISTOGRAM VIEW",4,titleLabel.height-8);

        titleLabel.endDraw();
        //make it the right size so we don't have to rescale later
        grid = createImage(width-OFFSET, height-OFFSET-5, ARGB);

        int numGridLines = ((110-Math.abs(top))/10);
        gridLineOffset = (grid.height)/numGridLines; //the space between

        vertLabel = new PGraphics2D();
        vertLabel.setParent(this);
        vertLabel.setPrimary(false);
        vertLabel.setSize(OFFSET, height-5);
        vertLabel.beginDraw();
        vertLabel.background(BACKGROUND_COLOR);
        vertLabel.fill(GRID_TEXT_COLOR);
        vertLabel.stroke(100);//GRID_COLOR);
        vertLabel.textFont(GRID_TEXT_FONT);
        vertLabel.textAlign(RIGHT);
        //draw straightVertical line
        vertLabel.line(vertLabel.width-4,OFFSET,vertLabel.width-4,vertLabel.height-5);
        //draw top vertical hash
        vertLabel.line(vertLabel.width-7, OFFSET, vertLabel.width-4, OFFSET);
        //draw top label
        vertLabel.text("-"+abs(top),vertLabel.width-7,OFFSET+5);

        grid.loadPixels();//gotta load em before you mess with em
        //draw the hash marks as grid-lines
        for(int i = 1; i<numGridLines; i++){
            //draw vertical hashes to match 
            vertLabel.line(vertLabel.width-7, i*gridLineOffset+OFFSET,
                                            vertLabel.width-4, i*gridLineOffset+OFFSET);
            //draw db level labels
            vertLabel.text("-"+(10*i+abs(top)),vertLabel.width-7,i*gridLineOffset+OFFSET+5);
            for(int j=0; j<grid.width;j++){
                if(j%6!=0 && j%6!=1 && j%6!=2){
                    grid.pixels[(i*gridLineOffset)*grid.width+j] = GRID_COLOR;
                }
            }
        }
        grid.updatePixels();//put em back where you found em
        vertLabel.endDraw();
                                     
        pg = new PGraphics2D();     //
        pg.setParent(this);         //  
        pg.setPrimary(true);       //   
        pg.setSize(width, height);//resize backBuffer\\
        updateScreenImage();//there's been resizing, so update the backbuffer
        //redraw();
    } 

Please tell me If I'm doing anything weird here causing the error. It's all pretty straight forward I hope.

Thanks!

also if pg is a PGraphics instead of PGraphics2D, all is well....

yeah, I was reading the docs for PGraphics2D and it said to instantiate it using it's constructor and then explicitly setting parent, size, etc... so far I'm not having issues with the PGraphics so I'm just going to use that. I was only assuming I'd get some speed increase with the PGraphics2D