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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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