Java基础之在窗口中绘图——绘制直线和矩形(Sketcher 2 drawing lines and rectangles)

控制台程序。

 import javax.swing.JComponent;
import java.util.*;
import java.awt.*;
import java.awt.geom.*; @SuppressWarnings("serial")
public class SketcherView extends JComponent implements Observer {
public SketcherView(Sketcher theApp) {
this.theApp = theApp;
} // Method called by Observable object when it changes
public void update(Observable o, Object rectangle) {
// Code to respond to changes in the model...
} // Method to draw on the view
@Override
public void paint(Graphics g) {
// Temporary code...
Graphics2D g2D = (Graphics2D)g; // Get a Java 2D device context g2D.setPaint(Color.RED); // Draw in red // Position width and height of first rectangle
Point2D.Float p1 = new Point2D.Float(50.0f, 10.0f);
float width1 = 60;
float height1 = 80; // Create and draw the first rectangle
Rectangle2D.Float rect = new Rectangle2D.Float(p1.x, p1.y, width1, height1);
g2D.draw(rect); // Position width and height of second rectangle
Point2D.Float p2 = new Point2D.Float(150.0f, 100.0f);
float width2 = width1 + 30;
float height2 = height1 + 40; // Create and draw the second rectangle
g2D.draw(new Rectangle2D.Float(
(float)(p2.getX()), (float)(p2.getY()), width2, height2));
g2D.setPaint(Color.BLUE); // Draw in blue // Draw lines to join corresponding corners of the rectangles
Line2D.Float line = new Line2D.Float(p1,p2);
g2D.draw(line); p1.setLocation(p1.x + width1, p1.y);
p2.setLocation(p2.x + width2, p2.y);
g2D.draw(new Line2D.Float(p1,p2)); p1.setLocation(p1.x, p1.y + height1);
p2.setLocation(p2.x, p2.y + height2);
g2D.draw(new Line2D.Float(p1,p2)); p1.setLocation(p1.x - width1, p1.y);
p2.setLocation(p2.x - width2, p2.y);
g2D.draw(new Line2D.Float(p1, p2)); g2D.drawString("Lines and rectangles", 60, 250); // Draw some text } private Sketcher theApp; // The application object
}

其他部分与上一例相同。

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