diva.canvas.tutorial
Class SimpleTutorial

java.lang.Object
  diva.canvas.tutorial.SimpleTutorial

public class SimpleTutorial
extends java.lang.Object

This tutorial shows how to construct a JCanvas and place figures on it.

In this example, we create figures with a few different shapes, using the BasicFigure class in diva.canvas.toolbox, which takes an instance of Shape (an interface defined in the Java AWT) and draws it on the screen using given colors and strokes.

Each JCanvas contains by default an instance of GraphicsPane. To get the graphics pane from a JCanvas:

   GraphicsPane graphicsPane = (GraphicsPane)canvas.getCanvasPane();
 

The pane contains several layers, one of which is a foreground FigureLayer upon which figures are drawn and interacted with. To get the figure layer:

   FigureLayer layer = graphicsPane.getForegroundLayer();
 

There are three figures on the screen, each created using a different kind of shape. The code to create a rectangle and add it to the figure layer is:

   Figure rectangle = new BasicRectangle(10,10,100,100,Color.blue);
   layer.add(rectangle);
 

The code to create the curved shape is more complex, and uses an instance of java.awt.geom.GeneralPath.

    GeneralPath path = new GeneralPath();
    path.moveTo(120,240);
    path.lineTo(240,240);
    path.quadTo(180,120,120,240);
    path.closePath();
    Figure semi = new BasicFigure(path, Color.green);
    layer.add(semi);
 

The third figure is much the same, but uses an instance of diva.util.java2d.Polyline2D. Polyline2D is more efficient than GeneralPath, and should be used anytime only straight-line segments are needed.

Version:

$Id: SimpleTutorial.java 38798 2005-07-08 20:00:01Z cxh $

Author:

John Reekie

Field Summary

private JCanvas	canvas
private GraphicsPane	graphicsPane

Constructor Summary

SimpleTutorial()
Create a JCanvas and put it into a window

Method Summary

void	createBasicFigure() Create an odd-shaped figure.
void	createBasicRectangle() Create a rectangle figure.
void	createPolyline() Create a polyline.
static void	main(java.lang.String[] argv) Main function

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

canvas

private JCanvas canvas

graphicsPane

private GraphicsPane graphicsPane

Constructor Detail

SimpleTutorial

public SimpleTutorial()

Create a JCanvas and put it into a window

Method Detail

createBasicRectangle

public void createBasicRectangle()

Create a rectangle figure. The rectangle is an instance of the BasicRectangle class. This class, together with a number other useful predefined figure classes, is contained in the package diva.canvas.toolbox.

createBasicFigure

public void createBasicFigure()

Create an odd-shaped figure. The rectangle is an instance of the BasicShape class, which draws itself using any instance of the Java2D interface, java.awt.Shape. In this example, we use an instance of GeneralPath.

createPolyline

public void createPolyline()

Create a polyline. Again, this uses the BasicFigure class, but this time the shape is an instance of diva.util.Polyline2D.

main

public static void main(java.lang.String[] argv)

Main function