fractal.java

这个是一个计算表达式的java包

/*
<applet code="org.nfunk.jepexamples.Fractal" width=300 height=320>
<param name=initialExpression value="z*z+c">
</applet>
*/
package org.nfunk.jepexamples;

import java.applet.*;
import java.awt.*;
import java.awt.event.*;

public class Fractal extends Applet implements ActionListener {
	private static final long serialVersionUID = -1825231934586941116L;
	private TextField exprField, itField;
	private Button button;
	private FractalCanvas complexCanvas;


	/** Initializes the applet Fractal */
	public void init () {
		initComponents();
	}


	private void initComponents () {
		GridBagLayout gridbag = new GridBagLayout();
		GridBagConstraints c = new GridBagConstraints();

		setLayout(gridbag);
		c.fill = GridBagConstraints.BOTH;
		
		// Expression field
		String expr = getParameter("initialExpression");
		if (expr!=null)
			exprField = new TextField(expr);
		else
			exprField = new TextField("");


		exprField.setBackground (java.awt.Color.white);
		exprField.setName ("exprField");
		exprField.setFont (new Font ("Dialog", 0, 11));
		exprField.setForeground (Color.black);
		exprField.addTextListener (new java.awt.event.TextListener () {
			public void textValueChanged (java.awt.event.TextEvent evt) {
				exprFieldTextValueChanged (evt);
			}
		}
		);

		c.gridx = 0;
		c.gridy = 0;
		c.weightx = 1;
		gridbag.setConstraints(exprField, c);
		add(exprField);

		// RENDER BUTTON
		c.gridx = 1;
		c.gridy = 0;
		c.weightx = 0.2;
		button = new Button("Render");
		gridbag.setConstraints(button, c);
		add(button);
		button.addActionListener(this);

		// Iterations field
		itField = new TextField("20");
		itField.addTextListener (new java.awt.event.TextListener () {
			public void textValueChanged (java.awt.event.TextEvent evt) {
				itFieldTextValueChanged(evt);
			}
		}
		);

		c.gridx = 0;
		c.gridy = 1;
		c.weightx = 1;
		gridbag.setConstraints(itField, c);
		add(itField);


		// CANVAS
		c.gridx = 0;
		c.gridy = 2;
		c.gridwidth = 2;
		c.weighty = 1;
//		button2 = new Button("test");
		
		complexCanvas = new FractalCanvas(expr, exprField);
		gridbag.setConstraints(complexCanvas, c);
		add(complexCanvas);
	}



	private void exprFieldTextValueChanged (java.awt.event.TextEvent evt) {
		String newExpressionString = exprField.getText();
		complexCanvas.setExpressionString(newExpressionString);
		//complexCanvas.repaint();
	}

	private void itFieldTextValueChanged (java.awt.event.TextEvent evt) {
		Integer newIterationsValue = new Integer(itField.getText());
		complexCanvas.setIterations(newIterationsValue.intValue());
		//complexCanvas.repaint();
	}

	public void actionPerformed(ActionEvent ae) {
		String str = ae.getActionCommand();
		if (str.equals("Render")) {
			String newExpressionString = exprField.getText();
			complexCanvas.setExpressionString(newExpressionString);
			complexCanvas.repaint();
		}
	}
}