Temat: aplikacja paint, javascript

witam,
chciałbym przerobić kod, za pomocą którego rysuję ołówkiem, na rysowanie prostokąta,okręgu(elipsy) i linii.

// define a pencil brush for drawing free-hand lines
var PencilBrush = new Class({
initialize: function (lineWidth, drawingCxt) {
this.lineWidth = lineWidth;

// get the cursor associated with the pencil brush
this.getCursor = function () {
return "url(cursors/pencil_cursor.cur), crosshair";
};

this.setColour = function (colour) {
drawingCxt.fillStyle = drawingCxt.strokeStyle = colour;
drawingCxt.lineWidth = this.lineWidth;
drawingCxt.lineCap = "round";
drawingCxt.lineJoin = "round";
};

// draws a line to the x and y coordinates of the specified position
function drawLine(position) {
drawingCxt.lineTo(position.X, position.Y);
drawingCxt.stroke();
}

this.startDrawing = function (position) {
// start drawing by moving to the specified x and y coordinates
drawingCxt.beginPath();
drawingCxt.moveTo(position.X--, position.Y--);
drawLine(position);
};

this.draw = function (position) {
drawLine(position);
};

this.finishDrawing = function (position) {
// draw the line to the finishing coordinates
drawLine(position);
drawingCxt.closePath();
};
}
});
Pomoze ktoś?