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用java创建带图像的菜单来美化界面


  在windows的“开始”菜单上,会在菜单左侧显示一幅图像。很多基于windows的软件也有类似效果的菜单。用java swing可以制作出类似效果的菜单吗?答案当然是肯定的,而且非常简单。
  
  我们首先从swing的jpopupmenu组件进行扩展,让其接受一个图片,显示在左侧;或者接受一个字符串,动态生成图片后,在显示在左侧。为了避免准备图片的麻烦,我们就以动态生成内存图片为例,编写一个jimagedpopupmenu类。
  
  jimagedpopupmenu在创建时可以接受一个字符串,生成一副内存图片bufferedimage。然后,我们需要覆盖jcomponent的getinsets方法,重新计算inset的left值,将其在原数值基础上加上图片的宽度,然后返回:
  
  public insets getinsets() {
  insets insets = (insets)super.getinsets().clone();
  insets.left += imageicon.geticonwidth();
  return insets;
  }
  
  最后,覆盖paintcomponent方法,在原基础上增加图片的绘制:
  public void paintcomponent(graphics g) {
  super.paintcomponent(g);
  if (imageicon != null) {
  insets insets = getinsets();
  g.drawimage(imageicon.getimage(),
  insets.left - imageicon.geticonwidth(),
  insets.top,
  null);
  }
  }
  
  完整代码如下:
  
  import java.awt.*;
  import java.awt.event.*;
  import java.awt.geom.*;
  import java.awt.image.*;
  import javax.swing.*;
  
  public class imagemenu extends jpopupmenu {
  private font font = new font("dialog", font.bold, 13);
  private imageicon imageicon = null;
  
  public imagemenu(imageicon imageicon) {
  this.imageicon = imageicon;
  }
  
  public imagemenu(string text) {
  this.imageicon = createimage(text);
  }
  
  private imageicon createimage(string text) {
  bufferedimage bi = new bufferedimage(30, 1000, bufferedimage.type_int_argb);
  imageicon image = new imageicon(bi);
  graphics2d g2d = bi.creategraphics();
  
  gradientpaint paint = new gradientpaint(0, 0, color.yellow, 30, 10, color.red, true);
  g2d.setpaint(paint);
  
  g2d.fillrect(0, 0, bi.getwidth(), bi.getheight());
  
  affinetransform at = new affinetransform();
  at.rotate( -math.pi / 2);
  
  g2d.settransform(at);
  g2d.setcolor(color.white);
  g2d.setfont(font);
  g2d.drawstring(text, -180, bi.getwidth() / 2);
  
  return image;
  }
  
  public insets getinsets() {
  insets insets = (insets)super.getinsets().clone();
  insets.left += imageicon.geticonwidth();
  return insets;
  }
  
  public void paint(graphics g) {
  super.paint(g);
  if (imageicon != null) {
  insets insets = getinsets();
  g.drawimage(imageicon.getimage(),
  insets.left - imageicon.geticonwidth(),
  insets.top,
  null);
  }
  }
  
  public static void main(string[] args) {
  final jframe frame = new jframe();
  frame.setsize(600, 500);
  frame.settitle("imagemenu");
  final imagemenu menu = new imagemenu("windows xp perfessional");
  menu.add(new jmenuitem("winzip 8.0"));
  menu.addseparator();
  menu.add(new jmenuitem("programs"));
  menu.add(new jmenuitem("document"));
  menu.add(new jmenuitem("settings"));
  menu.add(new jmenuitem("search"));
  menu.add(new jmenuitem("help and support"));
  menu.add(new jmenuitem("run..."));
  menu.addseparator();
  menu.add(new jmenuitem("shut down..."));
  jlabel label = new jlabel("right click me to show image popup menu.");
  label.addmouselistener(new java.awt.event.mouseadapter() {
  public void mousereleased(mouseevent e) {
  if (e.ispopuptrigger()) {
  menu.show(frame, e.getpoint().x, e.getpoint().y);
  }
  }
  });
  frame.getcontentpane().add(label, borderlayout.center);
  frame.show();
  }
  }
  
  同样,采用这种方法,也可以将jmenu扩展出同样的效果

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