Draw array to canvas

Question

I'm trying to draw objects onto a canvas from an array, but the thing is, I have no clue how to? This must include the position and sizes of the shapes, and there will be more than one type of shape. The code I've got so far(It's inefficient/bad though)

public class MCanvas extends Canvas {
    private Object[] world = {};

    public void paint(Graphics g){  
        try{  
           // How to paint all the shapes from world here?
        } catch (NullPointerException e) {  
              System.out.println(e.toString());  
        }  
      } 

}

Any ideas? Thanks.

*"but the thing is, I have no clue how to?"* The thing is, that is not a question (even with shoving '?' on the end). What is your specific question? Also, why use AWT in this millennium? Here we use Swing. — Andrew Thompson, Mar 07 '13 at 19:16
Don't forget to call super.paint first. What are the shapes? — MadProgrammer, Mar 07 '13 at 19:18
@MadProgrammer They are dynamically added to the array, but mainly rectangles and ovals. — YepNepDep, Mar 07 '13 at 19:22
@AndrewThompson My question is how to draw shapes in the array to the canvas, and I've not seen any swing alternative for Canvas. I'm all open for change though. — YepNepDep, Mar 07 '13 at 19:23
This explanation might help: http://stackoverflow.com/a/15120594/300257 — Gilbert Le Blanc, Mar 07 '13 at 19:24
@MadProgrammer No, at the moment I'm doing them by the java.awt.Rectangle class... etc — YepNepDep, Mar 07 '13 at 19:36
*"I've not seen any swing alternative for Canvas."* 1) A `JPanel` (extended) is very similar to a `Canvas` 2) Alternately Swing can also display a `BufferedImage` in a `JLabel`, and we can obtain a `Graphics2D` from the image.. — Andrew Thompson, Mar 07 '13 at 23:57

score 0 · Accepted Answer · answered Mar 07 '13 at 20:03

If your using objects that extend from java.awt.Shape, you can translate and draw them by using a Graphics2D context

Since (some whe around Java 1.3/4), the paint engine is guaranteed to use Graphics2D instance.

public void paint(Graphics g){  
    super.paint(g);
    Graphics2D g2d = (Graphics2D)g;
    for (Object o : world) {
        if (o instanceof Shape) {
            Shape shape = (Shape)o;
            //if the shape isn't created with 
            // a location, you can translate them
            shape.translate(...,...);
            g2d.setColor(....);
            g2d.draw(shape);
            //g2d.fill(...);
        }
    }
}

You might like to take a look at 2D Graphics for more details.

Also, use a JPanel instead of Canvas and then override its paintComponent method

Have a look at Custom Painting for more details

Draw array to canvas

1 Answers1