/src/com/atlassian/uwc/ui/organizer/DNDTreeTargetListener.java

package com.atlassian.uwc.ui.organizer;



import java.awt.AlphaComposite;

import java.awt.Color;

import java.awt.Graphics;

import java.awt.Graphics2D;

import java.awt.Insets;

import java.awt.Point;

import java.awt.Rectangle;

import java.awt.dnd.DnDConstants;

import java.awt.dnd.DropTarget;

import java.awt.dnd.DropTargetDragEvent;

import java.awt.dnd.DropTargetDropEvent;

import java.awt.image.BufferedImage;



import javax.swing.JComponent;

import javax.swing.JTree;

import javax.swing.tree.DefaultMutableTreeNode;

import javax.swing.tree.DefaultTreeModel;

import javax.swing.tree.MutableTreeNode;

import javax.swing.tree.TreeCellRenderer;

import javax.swing.tree.TreePath;



public class DNDTreeTargetListener extends DropTarget {



	private TreePath sourceNodePath;



	private Rectangle lastDragOverRowBounds;



	private Rectangle lastDragImageArea;



	private Point lastDragLocation;



	public DNDTreeTargetListener() {

		super();

	}



	private TreePath getSourceNodePath() {

		return sourceNodePath;

	}



	public void setSourceNodePath(TreePath aPath) {

		sourceNodePath = aPath;

	}

	

	private DefaultMutableTreeNode getTargetParentNode(JTree aTree) {



		if (aTree.getSelectionPath() != null) {

			return (DefaultMutableTreeNode)aTree.getSelectionPath().getLastPathComponent();

		}



		Point location = ((DNDTreeTargetListener)aTree.getDropTarget()).getLastDragLocation();

		TreePath path = aTree.getClosestPathForLocation(location.x, location.y);

		MutableTreeNode targetNode = (MutableTreeNode)path.getLastPathComponent();

		return (DefaultMutableTreeNode)targetNode.getParent();

	}



	public void dragOver(DropTargetDragEvent anEvent) {



		JTree tree = (JTree)anEvent.getDropTargetContext().getComponent();

		Point eventLocation = anEvent.getLocation();

		

		DefaultMutableTreeNode targetParentNode = getTargetParentNode(tree);

		DefaultMutableTreeNode sourceNode = 

			(DefaultMutableTreeNode)getSourceNodePath().getLastPathComponent();

		

		// Check if source node is a child of target

		if (sourceNode.isNodeDescendant(targetParentNode)) {

			anEvent.rejectDrag();

			clearImage(tree);

		} else {

			anEvent.acceptDrag(DnDConstants.ACTION_MOVE);

			updateDragImage(tree, eventLocation);

		}



		

		updateScrolling(tree, eventLocation);

		updateDragMarker(tree, eventLocation);



		super.dragOver(anEvent);

	}



	private void updateDragImage(JTree aTree, Point aPoint) {



		BufferedImage dragImage = getDragImage(aTree, getSourceNodePath());



		if (dragImage == null) {

			return;

		}



		//Clear the last drag image.

		aTree.paintImmediately(getLastDragImageArea().getBounds());



		getLastDragImageArea().setRect(

				(int)aPoint.getX(),

				(int)aPoint.getY() - 17,

				dragImage.getWidth(),

				dragImage.getHeight());



		aTree.getGraphics().drawImage(

				dragImage,

				(int)aPoint.getX(),

				(int)aPoint.getY() - 17,

				aTree);

	}



	public BufferedImage getDragImage(JTree aTree, TreePath aNodeToDraw) {



		BufferedImage image = null;

		try {

			Rectangle nodeBounds = aTree.getPathBounds(aNodeToDraw);

			TreeCellRenderer treeRenderer = aTree.getCellRenderer();

			DefaultTreeModel treeModel = (DefaultTreeModel)aTree.getModel();

			boolean nIsLeaf = treeModel.isLeaf(aNodeToDraw.getLastPathComponent());



			JComponent node = (JComponent)treeRenderer.getTreeCellRendererComponent(

					aTree,

					aNodeToDraw.getLastPathComponent(),

					false,

					aTree.isExpanded(aNodeToDraw),

					nIsLeaf,

					0,

					false);



			node.setBounds(nodeBounds);

			image = new BufferedImage(

					node.getWidth(),

					node.getHeight(),

					java.awt.image.BufferedImage.TYPE_INT_ARGB_PRE);



			Graphics2D graphics = image.createGraphics();

			graphics.setComposite(AlphaComposite.getInstance(

						AlphaComposite.SRC_OVER, 0.75f));

			node.setOpaque(false);

			node.paint(graphics);

			graphics.dispose();



		} catch (RuntimeException re) {

			return null;

		}



		return image;

	}



	private Rectangle getLastDragImageArea() {



		if (lastDragImageArea == null) {

			lastDragImageArea = new Rectangle();

		}



		return lastDragImageArea;

	}



	private void updateScrolling(JTree aTree, Point aCursorLocation) {



		Insets autoScrollInsets = new Insets(20, 20, 20, 20);



		Rectangle outer = aTree.getVisibleRect();

		Rectangle inner = new Rectangle(

				outer.x + autoScrollInsets.left,

				outer.y + autoScrollInsets.top,

				outer.width - (autoScrollInsets.left + autoScrollInsets.right),

				outer.height - (autoScrollInsets.top + autoScrollInsets.bottom));



		if (!inner.contains(aCursorLocation)) {

			Rectangle scrollRect = new Rectangle(

					aCursorLocation.x - autoScrollInsets.left,

					aCursorLocation.y - autoScrollInsets.top,

					autoScrollInsets.left + autoScrollInsets.right,

					autoScrollInsets.top + autoScrollInsets.bottom);



			aTree.scrollRectToVisible(scrollRect);

		}

	}



	public void updateDragMarker(JTree aTree, Point aLocation) {



		setLastDragLocation(aLocation);



		int row = aTree.getRowForPath(

				aTree.getClosestPathForLocation(

					aLocation.x,

					aLocation.y));



		TreePath path = aTree.getPathForRow(row);

		if (path == null) {

			return;

		}



		Rectangle rowBounds = aTree.getPathBounds(path);



		int rby = rowBounds.y;

		int topBottomDist = 6;



		Point topBottom = new Point(

				rby - topBottomDist,

				rby	+ topBottomDist);



		if (topBottom.x <= aLocation.y &&

			topBottom.y >= aLocation.y) {



			paintInsertMarker(aTree, aLocation);



		} else {

			markNode(aTree, aLocation);

		}

	}



	private void markNode(JTree aTree, Point aLocation) {



		TreePath path = aTree.getClosestPathForLocation(aLocation.x, aLocation.y);

		if (path == null) {

			return;

		}



		if (getLastDragOverRowBounds() != null) {

			Graphics g = aTree.getGraphics();

			g.setColor(Color.white);

			g.drawLine(

					getLastDragOverRowBounds().x,

					getLastDragOverRowBounds().y,

					getLastDragOverRowBounds().x + getLastDragOverRowBounds().width,

					getLastDragOverRowBounds().y);

		}



		aTree.setSelectionPath(path);

		aTree.expandPath(path);

	}



	private void paintInsertMarker(JTree aTree, Point aLocation) {



		Graphics g = aTree.getGraphics();

		aTree.clearSelection();



		int row = aTree.getRowForPath(aTree.getClosestPathForLocation(

				aLocation.x,

				aLocation.y));



		TreePath path = aTree.getPathForRow(row);

		if (path == null) {

			return;

		}



		Rectangle rowBounds = aTree.getPathBounds(path);



		if (getLastDragOverRowBounds() != null) {

			g.setColor(Color.white);

			g.drawLine(

					getLastDragOverRowBounds().x,

				getLastDragOverRowBounds().y,

				getLastDragOverRowBounds().x + getLastDragOverRowBounds().width,

				getLastDragOverRowBounds().y);

		}



		if (rowBounds != null) {

			g.setColor(Color.black);

			g.drawLine(

				rowBounds.x,

				rowBounds.y,

				rowBounds.x	+ rowBounds.width,

				rowBounds.y);

		}



		setLastDragOverRowBounds(rowBounds);

	}



	private Rectangle getLastDragOverRowBounds() {

		return lastDragOverRowBounds;

	}



	private void setLastDragOverRowBounds(Rectangle aRowBounds) {

		lastDragOverRowBounds = aRowBounds;

	}



	public Point getLastDragLocation() {

		return lastDragLocation;

	}



	private void setLastDragLocation(Point aLocation) {

		lastDragLocation = aLocation;

	}



	public void dragExit(DropTargetDragEvent anEvent) {

		clearImage((JTree)anEvent.getDropTargetContext().getComponent());



		super.dragExit(anEvent);

	}



	public void drop(DropTargetDropEvent anEvent) {

		clearImage((JTree)anEvent.getDropTargetContext().getComponent());



		super.drop(anEvent);

	}



	private final void clearImage(JTree tree) {

		tree.paintImmediately(getLastDragImageArea().getBounds());

	}

}