path: root/dozentenmodul/src/main/java/org/openslx/dozmod/gui/control/JCheckBoxTree.java

package org.openslx.dozmod.gui.control;

import java.awt.BorderLayout;
import java.awt.Component;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.util.EventListener;
import java.util.EventObject;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map.Entry;

import javax.swing.JCheckBox;
import javax.swing.JPanel;
import javax.swing.JTree;
import javax.swing.tree.DefaultMutableTreeNode;
import javax.swing.tree.DefaultTreeSelectionModel;
import javax.swing.tree.TreeCellRenderer;
import javax.swing.tree.TreeModel;
import javax.swing.tree.TreeNode;
import javax.swing.tree.TreePath;

import org.openslx.bwlp.thrift.iface.Location;
import org.openslx.dozmod.util.FormatHelper;

/**
 * Credits to 'SomethingSomething': http://stackoverflow.com/a/21851201
 * 
 * With minor changes:
 *  - setCheckedState(): helper to set the selection within the tree
 *  - fully expand first level nodes after setting the model
 *  - removed partial highlight in updatePredecessorsWithCheckMode() 
 *  - hacked cellRenderer to properly use Location names (uses FormatHelper.locName())
 */
public class JCheckBoxTree extends JTree {

	private static final long serialVersionUID = -4194122328392241790L;

	JCheckBoxTree selfPointer = this;

	// Defining data structure that will enable to fast check-indicate the state
	// of each node
	// It totally replaces the "selection" mechanism of the JTree
	private class CheckedNode {
		boolean isSelected;
		boolean hasChildren;
		boolean allChildrenSelected;

		public CheckedNode(boolean isSelected_, boolean hasChildren_,
				boolean allChildrenSelected_) {
			isSelected = isSelected_;
			hasChildren = hasChildren_;
			allChildrenSelected = allChildrenSelected_;
		}
	}

	HashMap<TreePath, CheckedNode> nodesCheckingState;
	HashSet<TreePath> checkedPaths = new HashSet<TreePath>();

	// Defining a new event type for the checking mechanism and preparing
	// event-handling mechanism

	public class CheckChangeEvent extends EventObject {
		private static final long serialVersionUID = -8100230309044193368L;

		public CheckChangeEvent(Object source) {
			super(source);
		}
	}

	public interface CheckChangeEventListener extends EventListener {
		public void checkStateChanged(CheckChangeEvent event);
	}

	public void addCheckChangeEventListener(CheckChangeEventListener listener) {
		listenerList.add(CheckChangeEventListener.class, listener);
	}

	public void removeCheckChangeEventListener(CheckChangeEventListener listener) {
		listenerList.remove(CheckChangeEventListener.class, listener);
	}

	void fireCheckChangeEvent(CheckChangeEvent evt) {
		Object[] listeners = listenerList.getListenerList();
		for (int i = 0; i < listeners.length; i++) {
			if (listeners[i] == CheckChangeEventListener.class) {
				((CheckChangeEventListener) listeners[i + 1])
						.checkStateChanged(evt);
			}
		}
	}

	// Override
	public void setModel(TreeModel newModel) {
		super.setModel(newModel);
		resetCheckingState();
		// Hack to get rid of leaf nodes with an expand button
		// first expand all nodes
		for (int i = 0; i < this.getRowCount(); i++) {
			this.expandRow(i);
		}
		// Now collapse again if it's not first level
		for (int i = 0; i < this.getRowCount(); i++) {
			TreePath path = this.getPathForRow(i);
			if (path.getPathCount() > 1)
				this.collapseRow(i);
		}
	}
	// Preselection stuff
	public void setCheckedState(List<TreePath> paths, boolean check) {
		if (paths == null)
			return;
		for (TreePath path : paths) {
			if (path != null) {
				checkSubTree(path, check);
				if (check)
					this.expandPath(path);
			}
		}
		collapseFullySelectedNodes();
	}

	// New method that returns only the checked paths (totally ignores original
	// "selection" mechanism)
	public TreePath[] getCheckedPaths() {
		return checkedPaths.toArray(new TreePath[checkedPaths.size()]);
	}

	// Returns true in case that the node is selected, has children but not all
	// of them are selected
	public boolean isSelectedPartially(TreePath path) {
		CheckedNode cn = nodesCheckingState.get(path);
		return cn.isSelected && cn.hasChildren && !cn.allChildrenSelected;
	}
	// Collapses all nodes that have only selected children
	private void collapseFullySelectedNodes() {
		// the paths need to be sorted by length, otherwise some nodes will get expanded again
		// even though they should be collapsed
		for (Entry<TreePath, CheckedNode> it : nodesCheckingState.entrySet()) {
			TreePath path = it.getKey();
			CheckedNode cn = it.getValue();
			if (cn.hasChildren && cn.allChildrenSelected && !isCollapsed(path)) {
				collapsePath(path);
			}
		}
	}

	private void resetCheckingState() {
		nodesCheckingState = new HashMap<TreePath, CheckedNode>();
		checkedPaths = new HashSet<TreePath>();
		DefaultMutableTreeNode node = (DefaultMutableTreeNode) getModel()
				.getRoot();
		if (node == null) {
			return;
		}
		addSubtreeToCheckingStateTracking(node);
	}

	// Creating data structure of the current model for the checking mechanism
	private void addSubtreeToCheckingStateTracking(DefaultMutableTreeNode node) {
		TreeNode[] path = node.getPath();
		TreePath tp = new TreePath(path);
		CheckedNode cn = new CheckedNode(false, node.getChildCount() > 0, false);
		nodesCheckingState.put(tp, cn);
		for (int i = 0; i < node.getChildCount(); i++) {
			addSubtreeToCheckingStateTracking((DefaultMutableTreeNode) tp
					.pathByAddingChild(node.getChildAt(i))
					.getLastPathComponent());
		}
	}

	// Overriding cell renderer by a class that ignores the original "selection"
	// mechanism
	// It decides how to show the nodes due to the checking-mechanism
	private class CheckBoxCellRenderer extends JPanel implements
			TreeCellRenderer {
		private static final long serialVersionUID = -7341833835878991719L;
		JCheckBox checkBox;

		public CheckBoxCellRenderer() {
			super();
			this.setLayout(new BorderLayout());
			checkBox = new JCheckBox();
			add(checkBox, BorderLayout.CENTER);
			setOpaque(false);
		}

		@Override
		public Component getTreeCellRendererComponent(JTree tree, Object value,
				boolean selected, boolean expanded, boolean leaf, int row,
				boolean hasFocus) {
			DefaultMutableTreeNode node = (DefaultMutableTreeNode) value;
			Object obj = node.getUserObject();
			TreePath tp = new TreePath(node.getPath());
			CheckedNode cn = nodesCheckingState.get(tp);
			if (cn == null) {
				return this;
			}
			// HACK ...
			String textString;
			if (obj instanceof Location)
				textString = FormatHelper.locName((Location)obj);
			else
				textString = obj.toString();
			checkBox.setSelected(cn.isSelected);
			checkBox.setText(textString);
			checkBox.setOpaque(cn.isSelected && cn.hasChildren
					&& !cn.allChildrenSelected);
			return this;
		}
	}

	public JCheckBoxTree() {
		super();
		// remove default model
		((DefaultMutableTreeNode) this.getModel().getRoot()).removeAllChildren();
		// Disabling toggling by double-click
		this.setToggleClickCount(0);
		// Overriding cell renderer by new one defined above
		CheckBoxCellRenderer cellRenderer = new CheckBoxCellRenderer();
		this.setCellRenderer(cellRenderer);
		// Overriding selection model by an empty one
		DefaultTreeSelectionModel dtsm = new DefaultTreeSelectionModel() {
			private static final long serialVersionUID = -8190634240451667286L;

			// Totally disabling the selection mechanism
			public void setSelectionPath(TreePath path) {
			}

			public void addSelectionPath(TreePath path) {
			}

			public void removeSelectionPath(TreePath path) {
			}

			public void setSelectionPaths(TreePath[] pPaths) {
			}
		};
		// Calling checking mechanism on mouse click
		this.addMouseListener(new MouseListener() {
			public void mouseClicked(MouseEvent arg0) {
				TreePath tp = selfPointer.getPathForLocation(arg0.getX(),
						arg0.getY());
				if (tp == null) {
					return;
				}
				boolean checkMode = !nodesCheckingState.get(tp).isSelected;
				checkSubTree(tp, checkMode);
				updatePredecessorsWithCheckMode(tp, checkMode);
				// Firing the check change event
				fireCheckChangeEvent(new CheckChangeEvent(new Object()));
				// Repainting tree after the data structures were updated
				selfPointer.repaint();
			}

			public void mouseEntered(MouseEvent arg0) {
			}

			public void mouseExited(MouseEvent arg0) {
			}

			public void mousePressed(MouseEvent arg0) {
			}

			public void mouseReleased(MouseEvent arg0) {
			}
		});
		this.setSelectionModel(dtsm);
	}

	// When a node is checked/unchecked, updating the states of the predecessors
	protected void updatePredecessorsWithCheckMode(TreePath tp, boolean check) {
		TreePath parentPath = tp.getParentPath();
		// If it is the root, stop the recursive calls and return
		if (parentPath == null) {
			return;
		}
		CheckedNode parentCheckedNode = nodesCheckingState.get(parentPath);
		DefaultMutableTreeNode parentNode = (DefaultMutableTreeNode) parentPath
				.getLastPathComponent();
		parentCheckedNode.allChildrenSelected = true;
		parentCheckedNode.isSelected = false;
		for (int i = 0; i < parentNode.getChildCount(); i++) {
			TreePath childPath = parentPath.pathByAddingChild(parentNode
					.getChildAt(i));
			CheckedNode childCheckedNode = nodesCheckingState.get(childPath);
			// It is enough that even one subtree is not fully selected
			// to determine that the parent is not fully selected
			if (!childCheckedNode.allChildrenSelected) {
				parentCheckedNode.allChildrenSelected = false;
			}
		}
		if (parentCheckedNode.allChildrenSelected) {
			parentCheckedNode.isSelected = true;
		}
		if (parentCheckedNode.isSelected) {
			checkedPaths.add(parentPath);
		} else {
			checkedPaths.remove(parentPath);
		}
		// Go to upper predecessor
		updatePredecessorsWithCheckMode(parentPath, check);
	}

	// Recursively checks/unchecks a subtree
	protected void checkSubTree(TreePath tp, boolean check) {
		CheckedNode cn = nodesCheckingState.get(tp);
		cn.isSelected = check;
		DefaultMutableTreeNode node = (DefaultMutableTreeNode) tp
				.getLastPathComponent();
		for (int i = 0; i < node.getChildCount(); i++) {
			checkSubTree(tp.pathByAddingChild(node.getChildAt(i)), check);
		}
		cn.allChildrenSelected = check;
		if (check) {
			checkedPaths.add(tp);
		} else {
			checkedPaths.remove(tp);
		}
	}
}