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/*
 * Copyright © 1996-2009 GlobalMentor, Inc. 
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.globalmentor.swing.draw;

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.event.*;
import com.globalmentor.java.Objects;

/**
 * Strategy for drawing a shape on a component. An instance of the strategy must be registered as both a {@link MouseListener} and a {@link MouseMotionListener}
 * with the component on which the shape will be drawn.
 * @see Drawable
 * @author Garret Wilson
 */
public class DrawShapeStrategy extends MouseInputAdapter {

	/** The component in which the object will be drawn. */
	protected final Component component;

	/** The object being drawn, or null if no shape is being drawn. */
	private DrawShape drawShape;

	/**
	 * @return The object being drawn, or null if no shape is being drawn.
	 */
	public DrawShape getDrawShape() {
		return drawShape;
	}

	/**
	 * Sets the object being drawn.
	 * @param newDrawShape The new shape to draw, or null if no shape is to be drawn.
	 */
	public void setDrawShape(final DrawShape newDrawShape) {
		if(!Objects.equals(drawShape, newDrawShape)) { //if the drawing shape is actuallychanging
			if(drawShape != null) //if we already had a shape
				draw(drawShape); //undraw the shape
			drawShape = newDrawShape; //actually change the drawing shape
			if(drawShape != null) //if we now have a shape
				draw(drawShape); //draw the new shape
		}
	}

	/**
	 * Constructs a strategy with a drawable object.
	 * @param newComponent The component in which the object will be drawn.
	 * @param newDrawShape The object to draw.
	 */
	public DrawShapeStrategy(final Component newComponent, final DrawShape newDrawShape) {
		component = newComponent; //save the component in which the component should be drawn TODO should we automatically register ourselves with the component?
		drawShape = newDrawShape; //save the object being drawn
	}

	/**
	 * Constructs a strategy with no drawable object.
	 * @param newComponent The component in which the object will be drawn.
	 */
	public DrawShapeStrategy(final Component newComponent) {
		this(newComponent, null); //do the default construction without a shape to draw
	}

	/**
	 * Called when the mouse button is pressed in the associated component.
	 * @param mouseEvent The mouse event.
	 */
	public void mousePressed(final MouseEvent mouseEvent) {
		//TODO del Log.trace("mouse pressed");  //TODO del
		if(SwingUtilities.isLeftMouseButton(mouseEvent)) { //if the left button is pressed
			final DrawShape drawShape = getDrawShape(); //get the shape being drawn
			if(drawShape != null) { //if we have a shape
				draw(drawShape); //undraw the shape
				drawShape.setLocation(mouseEvent.getX(), mouseEvent.getY()); //set the location of the shape being drawn
				drawShape.setEndLocation(mouseEvent.getX(), mouseEvent.getY()); //set the ending of the shape being drawn to be the same as the beginning location
				drawShape.setPermanent(false); //show that, as the shape is being constructed, it is not yet permanent
				draw(drawShape); //draw the shape
			}
		}
	}

	/**
	 * Called when the mouse button is released in the associated component.
	 * @param mouseEvent The mouse event.
	 */
	public void mouseReleased(final MouseEvent mouseEvent) {
		if(SwingUtilities.isLeftMouseButton(mouseEvent)) { //if the left button was released
			final DrawShape drawShape = getDrawShape(); //get the shape being drawn
			if(drawShape != null) { //if we have a shape
				draw(drawShape); //undraw the shape
				drawShape.setPermanent(true); //show that the shape is now permanent
				draw(drawShape); //draw the shape
			}
		}
	}

	/**
	 * Called when the mouse is dragged in the associated component.
	 * @param mouseEvent The mouse event.
	 */
	public void mouseDragged(final MouseEvent mouseEvent) {
		if(SwingUtilities.isLeftMouseButton(mouseEvent)) { //if the left button was released
			final DrawShape drawShape = getDrawShape(); //get the shape being drawn
			if(drawShape != null) { //if we have a shape being drawn
				//TODO del Log.trace("trying to move shape");  //TODO del
				draw(drawShape); //undraw the shape
				drawShape.setEndLocation(mouseEvent.getX(), mouseEvent.getY()); //update the ending position
				draw(drawShape); //redraw the shape
			}
		}
	}

	/**
	 * Paints the shapes managed by this object.
	 * @param graphics The graphics context used for painting.
	 */
	public void paint(final Graphics graphics) {
		final DrawShape drawShape = getDrawShape(); //get the shape being drawn
		if(drawShape != null) { //if we have a shape
			draw(graphics, drawShape); //draw the shape using the graphics context
		}
	}

	/**
	 * Draws a drawable object on the component.
	 * @param drawable The object to draw.
	 */
	protected void draw(final Drawable drawable) { //TODO maybe move this to a DrawComponent or to some DrawUtilities
		final Graphics graphics = component.getGraphics(); //get the graphics context
		if(graphics != null) { //if graphics are available
			try {
				draw(graphics, drawable); //draw the object using the graphics context we just acquired
			} finally {
				graphics.dispose(); //always dispose of the graphics context we acquired
			}
		}
	}

	/**
	 * Draws a drawable object on the component.
	 * @param graphics The graphics context to use to draw the object.
	 * @param drawable The object to draw.
	 */
	protected static void draw(final Graphics graphics, final Drawable drawable) { //TODO maybe move this to a DrawComponent or to some DrawUtilities
		drawable.draw(graphics); //tell the object to draw itself
	}

}