在JComboBox中使用动画GIF [英] Using an animated GIF in a JComboBox

问题描述

我正在尝试在JComboBox中使用动画（GIF）图标。

I'm trying to use animated (GIF) icons in a JComboBox.

由于DefaultListCellRenderer基于JLabel，因此将ImageIcons放入其中时直接受支持。 ComboBoxModel。

As the DefaultListCellRenderer is based on JLabel, ImageIcons are directly supported when putting them into the the ComboBoxModel.

但是，这不适用于动画GIF。

However this does not work with animated GIFs.

在下拉菜单中，它们不显示在除非选择了所有选项，否则所有选项都可以使用（尽管在常规JLabel中使用GIF还是可以的）

In the dropdown they are not show at all unless they are selected (the GIFs do work when used in a regular JLabel though)

填充组合框的代码很简单：

The code to populate the combobox is straight forward:

ImageIcon[] data = new ImageIcon[4];
data[0] = new ImageIcon("icon_one.gif");
data[1] = new ImageIcon("icon_two.gif");
data[2] = new ImageIcon("icon_three.gif");
data[3] = new ImageIcon("icon_four.gif");
ComboBoxModel model = new DefaultComboBoxModel(data);
setModel(model);

icon_one.gif是静态的，显示时没有任何问题。其他动画。 （图像 已正确加载，因为如果我将这些图标中的任何一个直接分配给JLabel，它们都将显示得很好）

icon_one.gif is the static one and is shown without any problems. The others are animated. (The images are loaded correctly because if I assign any of those icons to a JLabel directly they are displayed just fine)

我也试图使用基于JPanel的我自己的ListCellRenderer（受此问题的答案启发： Java动画，而不使用JLabel ）。

I also tried to use my own ListCellRenderer based on a JPanel (inspired by the answer to this question: Java animated GIF without using a JLabel).

效果更好，但也不理想。仅当在显示下拉菜单时将鼠标移到图标上时，才会显示图标。因此，我猜这是一个重新出现的问题，尽管我不知道在哪里

That works a bit better but not ideal either. The icons are only shown if I move the mouse over them while the dropdown is shown. So I guess it's a repaiting issue, although I don't know where

这是我的JPanel中实现ListCellRenderer接口的部分。

This is the part from my JPanel that implements the ListCellRenderer interface.

public Component getListCellRendererComponent(JList list, Object value, int index, boolean isSelected, boolean cellHasFocus)
{
  this.image = ((ImageIcon)value).getImage();
  if (isSelected)
  {
    setBackground(list.getSelectionBackground());
    setForeground(list.getSelectionForeground());
  }
  else
  {
    setBackground(list.getBackground());
    setForeground(list.getForeground());
  }
  revalidate();
  repaint();

  return this;
}

调用revalidate（）和repaint（）的灵感是看JLabel.setIcon（）的代码

The call to revalidate() and repaint() was inspired by looking at the code of JLabel.setIcon()

paint（）方法也很简单：

The paint() method is straight forward as well:

public void paintComponent(Graphics g)
{
  super.paintComponent(g);
  if (image != null)
  {
    g.drawImage(image, 0, 0, this);
  }
}

有什么想法吗？我真的不需要这些图标在下拉菜单中进行动画处理（尽管那会很好），但我至少希望看到静态图像。

Any ideas? I don't really need those icons to be animated in the dropdown (although that would be nice) but I would at least like to see the static images.

推荐答案

此示例的灵感来自 AnimatedIconTableExample.java

import java.awt.*;
import java.awt.image.*;
import java.net.*;
import javax.swing.*;
import javax.swing.plaf.basic.*;
class MainPanel {
  public JComponent makeUI() {
    JComboBox combo = new JComboBox();
    URL url1 = getClass().getResource("static.png");
    URL url2 = getClass().getResource("animated.gif");
    combo.setModel(new DefaultComboBoxModel(new Object[] {
      new ImageIcon(url1), makeImageIcon(url2, combo, 1)
    }));
    JPanel p = new JPanel();
    p.add(combo);
    return p;
  }
  private static ImageIcon makeImageIcon(
      URL url, final JComboBox combo, final int row) {
    ImageIcon icon = new ImageIcon(url);
    icon.setImageObserver(new ImageObserver() {
      //http://www2.gol.com/users/tame/swing/examples/SwingExamples.html
      //AnimatedIconTableExample.java
      @Override public boolean imageUpdate(
          Image img, int infoflags, int x, int y, int w, int h) {
        if(combo.isShowing() && (infoflags & (FRAMEBITS|ALLBITS)) != 0) {
          if(combo.getSelectedIndex()==row) {
            combo.repaint();
          }
          BasicComboPopup p = (BasicComboPopup)
            combo.getAccessibleContext().getAccessibleChild(0);
          JList list = p.getList();
          if(list.isShowing()) {
            list.repaint(list.getCellBounds(row, row));
          }
        }
        return (infoflags & (ALLBITS|ABORT)) == 0;
      };
    });
    return icon;
  }
  public static void main(String[] args) {
    EventQueue.invokeLater(new Runnable() {
      @Override public void run() {
        createAndShowGUI();
      }
    });
  }
  public static void createAndShowGUI() {
    JFrame f = new JFrame();
    f.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
    f.getContentPane().add(new MainPanel().makeUI());
    f.setSize(320, 240);
    f.setLocationRelativeTo(null);
    f.setVisible(true);
  }
}

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