Get Canvas properties : Canvas « J2ME « Java Tutorial

1. Java Tutorial
2. J2ME
3. Canvas

import javax.microedition.lcdui.Canvas;
import javax.microedition.lcdui.Command;
import javax.microedition.lcdui.CommandListener;
import javax.microedition.lcdui.Display;
import javax.microedition.lcdui.Displayable;
import javax.microedition.lcdui.Form;
import javax.microedition.lcdui.Graphics;
import javax.microedition.lcdui.StringItem;
import javax.microedition.midlet.MIDlet;

public class AttributesMIDlet extends MIDlet 
                        implements CommandListener {

    private Display display;
        
    protected boolean started;
    private Command exitCommand;
    
    protected void startApp() {
        if (!started) {
            display = Display.getDisplay(this);
            Canvas canvas = new DummyCanvas();
            Form form = new Form("Attributes");
            exitCommand = new Command("Exit", Command.EXIT, 0);
            form.addCommand(exitCommand);
            
            boolean isColor = display.isColor();
            form.append(new StringItem(isColor ? "Colors: " : "Grays: ",
                                String.valueOf(display.numColors())));
            form.append(new StringItem("Width: ", String.valueOf(canvas.getWidth())));
            form.append(new StringItem("Height: ", String.valueOf(canvas.getHeight())));
            form.append(new StringItem("Pointer? ", String.valueOf(canvas.hasPointerEvents())));
            form.append(new StringItem("Motion? ",String.valueOf(canvas.hasPointerMotionEvents())));
            form.append(new StringItem("Repeat? ",String.valueOf(canvas.hasRepeatEvents())));
            form.append(new StringItem("Buffered? ", String.valueOf(canvas.isDoubleBuffered())));
            
            form.setCommandListener(this);

            display.setCurrent(form);
            
            started = true;
        }
    }

    protected void pauseApp() {
    }

    protected void destroyApp(boolean unconditional) {
    }

    public void commandAction(Command c, Displayable d) {
        if (c == exitCommand) {
            notifyDestroyed();
        }
    } 
    static class DummyCanvas extends Canvas {
        protected void paint(Graphics g) {
        }
    }
}

31.24.Canvas
	31.24.1.	extends Canvas to create your own drawable area
	31.24.2.	Get Canvas properties
	31.24.3.	Canvas key pressed and key typed events
	31.24.4.	Use Canvas to draw a clock
	31.24.5.	Canvas size
	31.24.6.	Navigatable Canvas
	31.24.7.	Canvas key event and navigate through arrow keys