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