How do I resize the JTree row around the TreeCellEditor

Question

I use a multiline JTextArea to edit the values in my JTree.

With some coaxing, I'm able to get the JTextArea to resize to accommodate the text inside it, but the JTree nodes/rows around the editor don't move out of the way. (SCCEE w/ Screenshot below)

How do I get JTree to "reflow" all its nodes around the editor component?

import java.awt.*;
import java.awt.event.*;
import java.util.*;
import javax.swing.*;
import javax.swing.event.*;
import javax.swing.tree.*;

public final class TextAreaEditorForJTree {

    public static final String INITIAL_TEXT = "Line 1\nLine 2\nLine 3";

    public static void main(String args[]) {

        JTree tree = createSimpleTree();

        addTextAreaEditor(tree);

        JScrollPane scrollPane = new JScrollPane(tree);

        JFrame frame = new JFrame();
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.add(scrollPane, BorderLayout.CENTER);
        frame.setSize(300, 300);
        frame.setVisible(true);
    }

    private static JTree createSimpleTree() {
        DefaultMutableTreeNode root = new DefaultMutableTreeNode(INITIAL_TEXT);

        for (int i = 0; i < 10; i++) {
            MutableTreeNode child = new DefaultMutableTreeNode(INITIAL_TEXT);
            root.add(child);
        }

        JTree tree = new JTree(root);
        tree.setEditable(true);
        tree.setShowsRootHandles(true);

        return tree;
    }

    private static void addTextAreaEditor(JTree tree) {
        TreeCellEditor editor = new TextAreaTableCellEditor();
        tree.setCellEditor(editor);
    }

    private static final class TextAreaTableCellEditor extends AbstractCellEditor implements TreeCellEditor {

        private final JPanel panel;
        private final JLabel label;
        private final JTextArea textArea;
        private DefaultMutableTreeNode currentNode;

        public TextAreaTableCellEditor() {

            label = new JLabel("Editor:");

            textArea = new JTextArea();
            textArea.setColumns(10);

            panel = new JPanel();
            BoxLayout boxLayout = new BoxLayout(panel, BoxLayout.X_AXIS);
            panel.setLayout(boxLayout);
            panel.add(label);
            panel.add(textArea);

            textArea.addComponentListener(new ComponentListener() {

                @Override
                public void componentResized(ComponentEvent e) {
                    setSizeToPreferredSizeLater();
                }

                @Override
                public void componentShown(ComponentEvent e) {
                    setSizeToPreferredSizeLater();
                }

                @Override
                public void componentMoved(ComponentEvent e) {
                }

                @Override
                public void componentHidden(ComponentEvent e) {
                }
            });

            textArea.getDocument().addDocumentListener(new DocumentListener() {
                public void insertUpdate(DocumentEvent e) {
                    setSizeToPreferredSizeLater();
                }

                public void removeUpdate(DocumentEvent e) {
                    setSizeToPreferredSizeLater();
                }

                public void changedUpdate(DocumentEvent e) {
                    setSizeToPreferredSizeLater();
                }
            });
        }

        private void setSizeToPreferredSizeLater() {
            SwingUtilities.invokeLater(new Runnable() {
                @Override
                public void run() {
                    panel.setSize(panel.getPreferredSize());
                }
            });

        }

        public Object getCellEditorValue() {
            return textArea.getText();
        }

        public boolean isCellEditable(EventObject anEvent) {
            return true;
        }

        public boolean shouldSelectCell(EventObject anEvent) {
            return true;
        }

        public boolean stopCellEditing() {
            currentNode.setUserObject(textArea.getText());
            return true;
        }

        public void cancelCellEditing() {
            currentNode.setUserObject(textArea.getText());
        }

        public Component getTreeCellEditorComponent(final JTree tree, Object value, boolean isSelected, boolean expanded, boolean leaf, int row) {

            this.currentNode = ((DefaultMutableTreeNode) value);

            textArea.setText((String) currentNode.getUserObject());

            return panel;
        }
    }
}

Screenshot of SCCEE - The editor (Gray box and text to it's right) appears on-top-of all the other tree nodes.

Answer 1

I've found a solution to my problem, and it's very similar to the implementation in the answer to a related question. If you're just dealing with renderers, then you may be better served by reviewing the other question and answer, but in my case I'm dealing with an editor that is resizing as I type.

The key in both cases it to call AbstractLayoutCache.invalidateSizes(). This cache in a protected member of BasicTreeUI, which you can get from JTree.getUI() (this assumes that your tree's L&F extends BasicTreeUI)

You should note that while the method is called "invalidateSizes", it really invalidates all the node bounds. The node bounds also include the possition of the components. I would really rather extend the UI object or insert a forwarding/proxy object, but I wasn't able to find a solution in the time alloted.

After the size/bounds are invalided, a call to tree.repaint() will update the UI to show the new editor's size.

Ok, so I found two appoaches to calling this method, neither do I really like... but they do work:

private static class MyJTree extends JTree {
    ...
    public void invalidateNodeBoundsViaSideEffect() {
        if (ui instanceof BasicTreeUI) {
            BasicTreeUI basicTreeUI = (BasicTreeUI) ui;
            basicTreeUI.setLeftChildIndent(basicTreeUI.getLeftChildIndent());
        }}

    public void invalidateNodeBoundsViaRefection() {
        if (ui instanceof BasicTreeUI) {
            try {
                Field field = BasicTreeUI.class.getDeclaredField("treeState");
                field.setAccessible(true);

                AbstractLayoutCache treeState = (AbstractLayoutCache) field.get(ui);

                if (treeState != null) {
                    treeState.invalidateSizes();
                }
            } catch (Exception e) {
            }
        }}}

The revised SCCEE including this solution:

import java.awt.*;
import java.awt.event.*;
import java.lang.reflect.Field;
import java.util.*;
import javax.swing.*;
import javax.swing.event.*;
import javax.swing.plaf.basic.*;
import javax.swing.tree.*;

public final class TextAreaEditorForJTree2 {

    public static final String INITIAL_TEXT = "Line 1\nLine 2\nLine 3";

    public static void main(String args[]) {

        JTree tree = createSimpleTree();

        addTextAreaEditor(tree);

        JScrollPane scrollPane = new JScrollPane(tree);

        JFrame frame = new JFrame();
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.add(scrollPane, BorderLayout.CENTER);
        frame.setSize(300, 300);
        frame.setVisible(true);
    }

    private static JTree createSimpleTree() {

        DefaultMutableTreeNode root = new DefaultMutableTreeNode(INITIAL_TEXT);

        for (int i = 0; i < 10; i++) {
            MutableTreeNode child = new DefaultMutableTreeNode(INITIAL_TEXT);
            root.add(child);
        }

        JTree tree = new MyJTree(root);
        tree.setRowHeight(0);  // CRITICAL - Setting to '0' means the row heights are variable and the renderer's **bounds** should be recomputed more often!
        tree.setEditable(true);
        tree.setShowsRootHandles(true);

        return tree;
    }

    private static void addTextAreaEditor(JTree tree) {
        TreeCellEditor editor = new TextAreaTableCellEditor(tree);
        tree.setCellEditor(editor);
    }

    private static final class TextAreaTableCellEditor extends AbstractCellEditor implements TreeCellEditor {

        private final JPanel editorPanel;
        private final JLabel editorLabel;
        private final JTextArea textArea;
        private DefaultMutableTreeNode currentNode;
        private final JTree tree;

        public TextAreaTableCellEditor(final JTree target) {
            this.tree = target;

            editorLabel = new JLabel("Editor:");

            textArea = new JTextArea();
            textArea.setColumns(10);
            textArea.setLineWrap(true);
            textArea.setWrapStyleWord(true);

            editorPanel = new JPanel();
            BoxLayout boxLayout = new BoxLayout(editorPanel, BoxLayout.X_AXIS);
            editorPanel.setLayout(boxLayout);
            editorPanel.add(editorLabel);
            editorPanel.add(textArea);

            editorPanel.setSize(editorPanel.getPreferredSize());

            textArea.addComponentListener(new ComponentListener() {
                public void componentResized(ComponentEvent e) {somethingChanged();}
                public void componentShown(ComponentEvent e) {somethingChanged();}
                public void componentMoved(ComponentEvent e) {}
                public void componentHidden(ComponentEvent e) {}
            });

            textArea.getDocument().addDocumentListener(new DocumentListener() {
                public void insertUpdate(DocumentEvent e) {somethingChanged();}
                public void removeUpdate(DocumentEvent e) {somethingChanged();}
                public void changedUpdate(DocumentEvent e) {somethingChanged();}
            });
        }

        private void somethingChanged() {
            SwingUtilities.invokeLater(new Runnable() {
                @Override
                public void run() {
                    // TODO: skip if size is not changing
                    editorPanel.setSize(editorPanel.getPreferredSize());
                    ((MyJTree) tree).invalidateNodeBounds();
                    tree.repaint();
                }
            });
        }

        public Object getCellEditorValue() {
            return textArea.getText();
        }

        public boolean isCellEditable(EventObject anEvent) {
            return true;
        }

        public boolean shouldSelectCell(EventObject anEvent) {
            return true;
        }

        public boolean stopCellEditing() {
            currentNode.setUserObject(textArea.getText());
            return true;
        }

        public void cancelCellEditing() {
            currentNode.setUserObject(textArea.getText());
        }

        public Component getTreeCellEditorComponent(final JTree tree, Object value, boolean isSelected, boolean expanded, boolean leaf, int row) {
            this.currentNode = ((DefaultMutableTreeNode) value);
            textArea.setText((String) currentNode.getUserObject());
            return editorPanel;
        }
    }

    private static class MyJTree extends JTree {

        public MyJTree(TreeNode root) {
            super(root);
        }

        public void invalidateNodeBounds() {
            invalidateNodeBoundsViaSideEffect();
            //invalidateNodeBoundsViaRefection();
        }

        public void invalidateNodeBoundsViaSideEffect() {
            if (ui instanceof BasicTreeUI) {
                BasicTreeUI basicTreeUI = (BasicTreeUI) ui;
                basicTreeUI.setLeftChildIndent(basicTreeUI.getLeftChildIndent());
            }
        }

        public void invalidateNodeBoundsViaRefection() {

            if (ui instanceof BasicTreeUI) {

                try {
                    Field field = BasicTreeUI.class.getDeclaredField("treeState");
                    field.setAccessible(true);

                    AbstractLayoutCache treeState = (AbstractLayoutCache) field.get(ui);

                    if (treeState != null) {
                        treeState.invalidateSizes();
                    }
                } catch (Exception e) {
                }
            }
        }
    }
}