Bad performance with Canvas and extensive clipping

[Tom Schindl]

Hi,

Maybe as some of you might know I've been working since sometime on SWT
on JavaFX and to implement direct drawing operations we use JavaFX-Canvas.

I've today tried to run a heavy direct drawing grid implementation and
it performed very bad because it makes heavy use of clipping.

For a grid I've counted ~1500 clipping operations the library works
something like this:

boolean activeClip;
Canvas canvas = new Canvas();

public void setClipping(PathIterator pathIterator) {
  GraphicsContext gc = canvas.getGraphicsContext2D();
  if(activeClip) {
    gc.restore();
    activeClip= false;
  }

  if( pathIterator == null ) {
    return;
  }

  activeClip = true;
  float coords[] = new float[6];
  gc.save();
                gc.beginPath();
                
                float x = 0;
                float y = 0;
                
                
                gc.moveTo(0, 0);
                
                while( ! pathIterator.isDone() ) {
                        switch (pathIterator.currentSegment(coords)) {
                        case PathIterator.SEG_CLOSE:
                                gc.lineTo(x, y);
                                break;
                        case PathIterator.SEG_CUBICTO:
                                gc.bezierCurveTo(coords[0], coords[1], 
coords[2], coords[3],
coords[4], coords[5]);
                                break;
                        case PathIterator.SEG_LINETO:
                                gc.lineTo(coords[0], coords[1]);
                                break;
                        case PathIterator.SEG_MOVETO:
                                gc.moveTo(coords[0], coords[1]);
                                x = coords[0];
                                y = coords[1];
                                break;
                        case PathIterator.SEG_QUADTO:
                                gc.quadraticCurveTo(coords[0], coords[1], 
coords[2], coords[3]);
                                break;
                        default:
                                break;
                        }
                        pathIterator.next();
                }
                
                gc.clip();
                gc.closePath();
}

Am I doing something ultimately wrong, totally wrong? Has anyone an idea
how I would work around the problem?

Tom