custom icons in JTree

[Dave Robbins]

OK, I'm stumped
trying to use custom icons for the nodes in a JTree
I made my own TreeCellRenderer

class MyTreeCellRenderer extends DefaultTreeCellRenderer implements TreeCellRenderer {
        public java.awt.Component getTreeCellRendererComponent( javax.swing.JTree tree,
                                                 Object value,
                                                 boolean bSelected,
                                                 boolean bExpanded,
                                                 boolean bLeaf,
                                                 int iRow,
                                                 boolean bHasFocus ) {
 
            // Find out which node we are rendering and get its text
            DefaultMutableTreeNode node = (DefaultMutableTreeNode)value;
            String labelText = (String)node.toString();
            setText(labelText);
            setForeground(java.awt.Color.green);
            setBackground(java.awt.Color.red);
            setOpenIcon(myIcon);
            setClosedIcon(myIcon);
            setLeafIcon(myIcon);
            setIcon(myIcon);
 
            return this;
        }
    }
    

and I used it like this when I create and populate my tree

                top = new DefaultMutableTreeNode("My App");
                treeModel = new DefaultTreeModel(top);
                jTree1 = new javax.swing.JTree(treeModel);
                myIcon = createImageIcon("images/icon.jpg");
                if (myIcon != null) {
                    renderer = new MyTreeCellRenderer();
                    jTree1.setCellRenderer(renderer);
                }
                

I run the code in a debugger and everything seems to work right but on the GUI there are just default icons
I even made a JLabel and set the icon to display in it and that works so the image is getting loaded
I'm guessing there's something wrong with the order in which I'm doing things, like when stuff get's created but it looks right to me
I can put a breakpoint in MyTreeCellRenderer and see the code jump in there

any ideas???

Dave

[Paul Clapham]

Do your tree nodes REALLY contain DefaultMutableTreeNode objects as their user objects? If not, then your renderer would be throwing a class-cast exception where you cast the value to that type. And if you do, that's a really strange design.

[Dave Robbins]

my nodes are objects that extend DefaultMutableTreeNodes
they're extended such that they contain info about how to lookup stuff for that node in a database
the functions I'm calling, set*Icon haven't been overloaded so I think what I'm doing is ok, but I could be wrong
I have been before

Dave

[Dave Robbins]

hmm, Paul
I think you're onto something
investigating further
thanks

Dave

[Dave Robbins]

doh
what's behind door number 3
it would be a "really strange design" :roll:
I shouldn't extend DefaultMutableTree node like I'm doing
I should use setUserObject to include the additional info
my bad

Thanks
Dave

[Craig Wood]

import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.*;
import javax.imageio.ImageIO;
import javax.swing.*;
import javax.swing.tree.*;
 
public class TreeIcons
{
    BufferedImage[] images;
 
    public TreeIcons(BufferedImage[] images)
    {
        this.images = images;
    }
 
    private JPanel getContent()
    {
        JPanel panel = new JPanel(new GridLayout(1,0));
        panel.add(new JScrollPane(getLeftTree()));
        panel.add(new JScrollPane(getRightTree()));
        return panel;
    }
 
    private JTree getLeftTree()
    {
        JTree tree = getTree();
        DefaultTreeCellRenderer renderer =
                (DefaultTreeCellRenderer)tree.getCellRenderer();
        // make changes to renderer for this tree
        // works okay if the size of the new images does
        // not exceed the size of the default images
        renderer.setClosedIcon(new ImageIcon(images[0]));
        renderer.setOpenIcon(new ImageIcon(images[1]));
        renderer.setLeafIcon(new ImageIcon(images[2]));
        return tree;
    }
 
    private JTree getRightTree()
    {
        JTree tree = getTree();
        // set a renderer that allows more fine-grained
        // control of rendering for varying conditions
        tree.setCellRenderer(new IconRenderer(images));
        return tree;
    }
 
    private JTree getTree()
    {
        String[] birds = {
            // branches  |<-- child leaf nodes -->|
            "hawks",   "gray",    "red-tailed", "rough-legged",
            "falcons", "harrier", "kestrel",    "kite", 
            "owls",    "barred",  "saw-whet",   "snowy"
        };
        DefaultMutableTreeNode root = new DefaultMutableTreeNode("birds");
        DefaultMutableTreeNode[] nodes = new DefaultMutableTreeNode[birds.length];
        for(int j = 0; j < nodes.length; j++)
            nodes[j] = new DefaultMutableTreeNode(birds[j]);
        for(int j = 0; j < 9; j += 4)
        {
            root.insert(nodes[j], j % 3);
            for(int k = j + 1; k < j + 4; k++)
                nodes[j].insert(nodes[k], k - j - 1);
        }
        DefaultTreeModel model = new DefaultTreeModel(root);
        return new JTree(model);
    }
 
    public static void main(String[] args) throws IOException
    {
        String[] ids = { "closed16", "open16", "leaf16" };
        BufferedImage[] bis = new BufferedImage[ids.length];
        for(int j = 0; j < bis.length; j++)
            bis[j] = ImageIO.read(new File("images/" + ids[j] + ".gif"));
        // to make uniform changes for all JTrees in this app
        //UIManager.put("Tree.closedIcon", new ImageIcon(bis[0]));
        //UIManager.put("Tree.openIcon",   new ImageIcon(bis[1]));
        //UIManager.put("Tree.leafIcon",   new ImageIcon(bis[2]));
        JFrame f = new JFrame();
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.setContentPane(new TreeIcons(bis).getContent());
        f.setSize(500,400);
        f.setLocation(200,200);
        f.setVisible(true);
    }
}
 
class IconRenderer extends DefaultTreeCellRenderer
{
    ImageIcon closedIcon;
    ImageIcon openIcon;
    ImageIcon leafIcon;
 
    public IconRenderer(BufferedImage[] images)
    {
        closedIcon = new ImageIcon(images[0]);
        openIcon   = new ImageIcon(images[1]);
        leafIcon   = new ImageIcon(images[2]);
    }
 
    public Component getTreeCellRendererComponent(JTree tree,
                                                  Object value,
                                                  boolean sel,
                                                  boolean expanded,
                                                  boolean leaf,
                                                  int row,
                                                  boolean hasFocus)
    {
        // start with default behavior
        super.getTreeCellRendererComponent(tree, value, sel, expanded, 
                                           leaf, row, hasFocus);
 
        // customize based on local conditions/state
        DefaultMutableTreeNode node = (DefaultMutableTreeNode)value;
        String userObject = (String)node.getUserObject();
        boolean isOwl = userObject.equalsIgnoreCase("owls");
        if(isOwl)
            setIcon(closedIcon);
        else if(leaf)
            setIcon(leafIcon);
        else if(expanded)
            setIcon(openIcon);
        return this;
    }
}

[Dave Robbins]

ok, found the problem
the folks who think IDE's are terrible and you should write all your code with a text editor are gonna laugh
after I built my nice little tree with all the custom icons, the auto-generated code that netbeans had written came along behind me and re-initialized my tree
interestingly, now that I've found the problem I see that creating my own treenodes that extend a DefaultMutableTreeNode isn't a problem
I didn't think it should be
but now that I see how I can use setUserObject to do the same thing I see that it's kinda a waste of time

Thanks for all the help
Dave