JTree将节点背景设置为非不透明 [英] JTree set background of node to non-opaque

问题描述

请看一下SSCCE。如何使未选择的树节点的背景透明。目前，未选择节点的背景为白色。但是，我的单元格渲染器应该将其绘制为非透明（如果未选中）（选择时为绿色......它的作用）。最后，我希望非选定节点只是没有背景的文本，因为SSCCE中红色的区域在我的应用程序中有一个渐变填充。

  import java.awt.BorderLayout; 
 import java.awt.Color; 
 import java.awt.Component; 
 import java.awt.Container; 
 
 import javax.swing.JFrame; 
 import javax.swing.JScrollPane; 
 import javax.swing.JTree; 
 import javax.swing.tree.DefaultMutableTreeNode; 
 import javax.swing.tree.DefaultTreeCellRenderer; 
 
公共类SimpleTree扩展JFrame 
 {
 public static void main（final String [] args）
 {
 new SimpleTree（）; 
} 
 
 public SimpleTree（）
 {
 super（创建一个简单的JTree）; 
 final Container content = this.getContentPane（）; 
 content.setBackground（Color.RED）; 
 final Object [] hierarchy = {javax.swing，javax.swing.border，javax.swing.colorchooser，javax.swing.event，javax.swing.filechooser，new Object [] {javax.swing.plaf，javax.swing.plaf.basic，javax.swing.plaf.metal，javax.swing.plaf.multi}，javax.swing.table ，
 new Object [] {javax.swing.text，new Object [] {javax.swing.text.html，javax.swing.text.html.parser}，javax.swing .text.rtf}，javax.swing.tree，javax.swing.undo}; 
 final DefaultMutableTreeNode root = this.processHierarchy（hierarchy）; 
 final JTree tree = new JTree（root）; 
 tree.setOpaque（false）; 
 tree.setCellRenderer（new MyCellRenderer（））; 
 final JScrollPane scroller = new JScrollPane（tree）; 
 scroller.getViewport（）。setOpaque（false）; 
 scroller.setOpaque（false）; 
 content.add（scroller，BorderLayout.CENTER）; 
 this.setSize（275,300）; 
 this.setVisible（true）; 
} 
 
 / ** 
 *小例程将使节点脱离数组中的第一个条目，
 *然后从后续条目中生成节点并使他们是第一个
 *的子节点。对于
 *数组的条目，递归重复该过程。 
 * / 
 
 private DefaultMutableTreeNode processHierarchy（final Object [] hierarchy）
 {
 final DefaultMutableTreeNode node = new DefaultMutableTreeNode（hierarchy [0]）; 
 DefaultMutableTreeNode child; 
 for（int i = 1; i< hierarchy.length; i ++）
 {
 final Object nodeSpecifier = hierarchy [i]; 
 if（nodeSpecifier instanceof Object []）//即带子节点的节点
 child = this.processHierarchy（（Object []）nodeSpecifier）; 
 else 
 child = new DefaultMutableTreeNode（nodeSpecifier）; //即Leaf 
 node.add（child）; 
} 
 return（node）; 
} 
 
公共类MyCellRenderer扩展DefaultTreeCellRenderer 
 {
 @Override 
 public Component getTreeCellRendererComponent（最终的JTree树，最终的Object值，最终的boolean sel，final boolean expanded，final boolean leaf，final int row，final boolean hasFocus）
 {
 final Component ret = super.getTreeCellRendererComponent（tree，value，sel，expanded，leaf，row，hasFocus）; 
 
 final DefaultMutableTreeNode node =（（DefaultMutableTreeNode）（value））; 
 
 this.setText（value.toString（））; 
 if（sel）
 {
 this.setOpaque（true）; 
 this.setBackground（Color.GREEN）; 
 
} 
 else 
 {
 this.setOpaque（false）; 
 this.setBackground（null）; 
} 
返回ret; 
} 
} 
} 
  

解决方案

你应覆盖。

不要扩展 JFrame 不必要地创建一个实例并使用它。

不要在<$ c $上调用 setSize c> JFrame 而是使用正确的 LayoutManager 和/或覆盖 getPreferredSize（）并调用 pack（）在 JFrame 上，然后将其设置为可见但在添加所有组件之后。

请记住使用 DISPOSE_ON_CLOSE 或 EXIT_ON_CLOSE JFrame #setDefaultCloseOperation c>（ DISPOSE_XXX 通常是首选的unles使用计时器 s，因为这将允许 main（String [] args）在Gui关闭后继续执行）。

Please have a look at the SSCCE. How can I make the non-selected tree nodes' background transparent. At the moment the background of non-selected nodes is white. My cell renderer, however, should paint it non-opaque if it is not selected (and green when selected...what it does). In the end I want non-selected nodes to be just text without background, since the area which is red in the SSCCE has a gradient fill in my application.

    import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Component;
import java.awt.Container;

import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JTree;
import javax.swing.tree.DefaultMutableTreeNode;
import javax.swing.tree.DefaultTreeCellRenderer;

public class SimpleTree extends JFrame
{
    public static void main(final String[] args)
    {
        new SimpleTree();
    }

    public SimpleTree()
    {
        super("Creating a Simple JTree");
        final Container content = this.getContentPane();
        content.setBackground(Color.RED);
        final Object[] hierarchy = { "javax.swing", "javax.swing.border", "javax.swing.colorchooser", "javax.swing.event", "javax.swing.filechooser", new Object[] { "javax.swing.plaf", "javax.swing.plaf.basic", "javax.swing.plaf.metal", "javax.swing.plaf.multi" }, "javax.swing.table",
                        new Object[] { "javax.swing.text", new Object[] { "javax.swing.text.html", "javax.swing.text.html.parser" }, "javax.swing.text.rtf" }, "javax.swing.tree", "javax.swing.undo" };
        final DefaultMutableTreeNode root = this.processHierarchy(hierarchy);
        final JTree tree = new JTree(root);
        tree.setOpaque(false);
        tree.setCellRenderer(new MyCellRenderer());
        final JScrollPane scroller = new JScrollPane(tree);
        scroller.getViewport().setOpaque(false);
        scroller.setOpaque(false);
        content.add(scroller, BorderLayout.CENTER);
        this.setSize(275, 300);
        this.setVisible(true);
    }

    /**
     * Small routine that will make node out of the first entry in the array,
     * then make nodes out of subsequent entries and make them child nodes of
     * the first one. The process is repeated recursively for entries that are
     * arrays.
     */

    private DefaultMutableTreeNode processHierarchy(final Object[] hierarchy)
    {
        final DefaultMutableTreeNode node = new DefaultMutableTreeNode(hierarchy[0]);
        DefaultMutableTreeNode child;
        for (int i = 1; i < hierarchy.length; i++)
        {
            final Object nodeSpecifier = hierarchy[i];
            if (nodeSpecifier instanceof Object[]) // Ie node with children
                child = this.processHierarchy((Object[]) nodeSpecifier);
            else
                child = new DefaultMutableTreeNode(nodeSpecifier); // Ie Leaf
            node.add(child);
        }
        return (node);
    }

    public class MyCellRenderer extends DefaultTreeCellRenderer
    {
        @Override
        public Component getTreeCellRendererComponent(final JTree tree, final Object value, final boolean sel, final boolean expanded, final boolean leaf, final int row, final boolean hasFocus)
        {
            final Component ret = super.getTreeCellRendererComponent(tree, value, sel, expanded, leaf, row, hasFocus);

            final DefaultMutableTreeNode node = ((DefaultMutableTreeNode) (value));

            this.setText(value.toString());
            if (sel)
            {
                this.setOpaque(true);
                this.setBackground(Color.GREEN);

            }
            else
            {
                this.setOpaque(false);
                this.setBackground(null);
            }
            return ret;
        }
    }
}

解决方案

You should override getBackgroundNonSelectionColor,getBackgroundSelectionColor and getBackground of DefaultTreeCellRenderer and return appropriate values like so:

public class MyCellRenderer extends DefaultTreeCellRenderer {

    @Override
    public Color getBackgroundNonSelectionColor() {
        return (null);
    }

    @Override
    public Color getBackgroundSelectionColor() {
        return Color.GREEN;
    }

    @Override
    public Color getBackground() {
        return (null);
    }

    @Override
    public Component getTreeCellRendererComponent(final JTree tree, final Object value, final boolean sel, final boolean expanded, final boolean leaf, final int row, final boolean hasFocus) {
        final Component ret = super.getTreeCellRendererComponent(tree, value, sel, expanded, leaf, row, hasFocus);

        final DefaultMutableTreeNode node = ((DefaultMutableTreeNode) (value));
        this.setText(value.toString());
        return ret;
    }
}

which will produce:

Other suggestions:

• Create and manipulate Swing components on Event Dispatch Thread.
• Dont extend JFrame unnecessarily rather create an instance and use that.
• Dont call setSize on JFrame rather use a correct LayoutManager and/or override getPreferredSize() and call pack() on JFrame before setting it visible but after adding all components.
• Remember to call JFrame#setDefaultCloseOperation with either DISPOSE_ON_CLOSE or EXIT_ON_CLOSE (DISPOSE_XXX is usually preferred unless using Timers as this will allow main(String[] args) to continue its execution after Gui has been closed).

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