import bsh.util.BshCanvas;   // BshCanvas simply buffers graphics

graph( int width, int height ) {
	scale=object();
	scale.x=100; scale.y=100;

	drawAxis() {
		graphics.setColor( Color.red );
		graphics.drawLine( 0, height/2, width, height/2 );
		graphics.drawLine( width/2, 0, width/2, height );
	}

	plot(x, y, Color color) {
		graphics.setColor( color );
		graphics.fillOval( (int)((x/scale.x+1)*(width/2))-1, 
			(int)((-y/scale.y+1)*(height/2))-1, 3, 3);
		canvas.repaint();
	}

	clear() {
		graphics.setColor( Color.white );
		graphics.fillRect(0,0,width,height);
		drawAxis();
		canvas.repaint();
	}

	setScale( x, y ) {
		scale.x=1.0*x;
		scale.y=1.0*y;
	}

	canvas=new BshCanvas(); 
	canvas.setSize( width, height );
	frame=frame( canvas );
	graphics=canvas.getBufferedGraphics();
	drawAxis();
	
	return this;
}

g=graph(400,200);
g.setScale(2*Math.PI,1.0);
for (x=-2*Math.PI; x<2*Math.PI; x+=0.1) {
    y=Math.sin(x);
    g.plot( x, y, Color.black );
}