gann-cdf / graphics

import org.gannacademy.cdf.graphics.Drawable;

import javax.imageio.ImageIO;

import javax.swing.*;

import java.awt.*;

import java.awt.image.BufferedImage;

import java.io.File;

import java.io.IOException;

import java.util.Stack;

/**

 * <p>A drawing panel receives and displays all drawing instructions</p>

 *

 * <p>In the default configuration (in which {@link AppWindow} is extended to construct a drawing), the drawing panel is

 * contained by an {@code AppWindow} object — an {@code AppWindow} has-a {@code DrawingPanel}, in the parlance of

 * the Advanced Placement exam, and a {@code DrawingPanel} has-many {@code Drawable} components.</p>

 *

 * @author <a href="https://github.com/gann-cdf/graphics/issues" target="_blank">Seth Battis</a>

 */

public class DrawingPanel extends JPanel {

  /**

   * {@value #DEFAULT_WIDTH} pixels

   */

  public static final int DEFAULT_WIDTH = 600;

  /**

   * {@value #DEFAULT_HEIGHT} pixels

   */

  public static final int DEFAULT_HEIGHT = 400;

  /**

   * {@link Color#WHITE}

   */

  public static final Color DEFAULT_BACKGROUND = Color.WHITE;

  /**

   * {@value #DEFAULT_IMAGE_FORMAT}

   */

  public static final String DEFAULT_IMAGE_FORMAT = "PNG";

  /*

   * TODO Not 100% confident that the stack is the right structure here -- it would be nice to let someone reorder the

   * components to effectively set their Z-depth (which could technically be done with a stack, but is not really in the

   * spirit of it all)

   */

  private Stack<Drawable> components;

  /**

   * Construct a drawing panel of default dimensions and background color

   */

  /**

   * <p>Construct a drawing panel with custom arguments</p>

   *

   * <p>Of potential interest: while setting a background color that is transparent reveals the light gray color of of

   * the enclosing {@link JFrame} underneath the drawing panel, it will save as a transparent PNG using

   * {@link #saveAs(String)}.</p>

   *

   * @param dimension  in pixels

   * @param background color

   */

  public DrawingPanel(Dimension dimension, Color background) {

    super();

    setPreferredSize(dimension);

    setBackground(background);

    components = new Stack<>();

  }

  /**

   * <p>Add a drawable component to the drawing panel</p>

   *

   * <p>While available for use, this method does not usually need to be called manually -- it is automatically called

   * by all {@link Drawable} component constructors. The {@link Drawable#setDrawingPanel(DrawingPanel)} method is

   * meant to be used to move a {@code Drawable} component from one drawing panel to another transparently.</p>

   *

   * @param component to be added

   */

  public synchronized void add(Drawable component) {

    if (!components.contains(component)) {

      components.push(component);

    }

  }

  /**

   * <p>Remove a drawable component from the drawing panel</p>

   *

   * <p>While available for use, this method dos not usually need to be called manually -- it is automatically called

   * by {@link Drawable#removeFromDrawingPanel()} and, if necessary, by

   * {@link Drawable#setDrawingPanel(DrawingPanel)}.</p>

   *

   * @param component to be removed

   * @return {@code true} if the component was present and removed, {@code false} otherwise

   */

  public synchronized boolean remove(Drawable component) {

    return components.remove(component);

  }

  /**

   * <p>Clear all drawable components from the drawing panel</p>

   *

   * <p>This does not destroy the drawable components &mdash; any references to these components outside of the drawing

   * panel will still be valid, but the components will no longer refer to this drawing panel.</p>

   */

  public void clear() {

    while (!components.isEmpty()) {

      components.peek().removeFromDrawingPanel();

    }

  }

  /**

   * <p>Repaint the contents of the drawing panel (drawable components) as-needed</p>

   *

   * <p>This method is called automatically by the enclosing {@link JFrame} to repaint the drawing panel as needed. It

   * is not meant to be called manually. If the drawing panel needs to be updated, a {@link #repaint()} request will

   * schedule the update.</p>

   *

   * <p>This method calls the {@link #draw(Graphics2D)} method to perform the actual drawing instructions</p>

   *

   * @param graphics context for drawing instructions

   * @see #draw(Graphics2D)

   */

  @Override

  public void paintComponent(Graphics graphics) {

    super.paintComponent(graphics);

    draw((Graphics2D) graphics);

  }

  /**

   * <p>Request drawing instructions from all contained drawing components</p>

   *

   * <p>This method encapsulates all of the drawing instructions necessary to display the current drawable components.

   * It is used by both the {@link #paintComponent(Graphics)} method to update the display and the {@link #saveAs(String)}

   * method to write the current drawable components to a file.</p>

   *

   * <p>This method calls the {@link #preDraw(Graphics2D)} method prior to making drawing instructions to

   * set any rendering hints or other configuration for the drawing.</p>

   *

   * @param graphics context for drawing instructions

   * @see Drawable#draw(Graphics2D)

   * @see #preDraw(Graphics2D)

   * @see #paintComponent(Graphics)

   * @see #saveAs(String, String)

   */

  protected synchronized void draw(Graphics2D graphics) {

    Graphics2D graphics2D = graphics;

    preDraw(graphics2D);

    for (Drawable component : components) {

      component.draw(graphics2D);

    }

  }

  /**

   * <p>Override this method to set custom graphics configurations</p>

   * <p>This method is called by {@link #draw(Graphics2D)} to configure any desired rendering hints or other

   * preconfiguration before executing the actual drawing instructions.</p>

   *

   * @param graphics context for drawing commands

   */

  public void preDraw(Graphics2D graphics) {

    graphics.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);

  }

  /**

   * Save the current drawing panel as a file using the default format

   *

   * @param path relative to the current working directory

   * @return {@code true} if the file was successfully written, {@code false} otherwise

   */

  public boolean saveAs(String path) {

    return saveAs(path, DEFAULT_IMAGE_FORMAT);

  }

  /**

   * Save the current drawing panel as a file

   *

   * @param path   relative to the current working directory

   * @param format of the image file (e.g. {@value #DEFAULT_IMAGE_FORMAT}

   * @return {@code true} if the file was successfully written, {@code false} otherwise

   */

  public boolean saveAs(String path, String format) {

    try {

      BufferedImage image = new BufferedImage(getWidth(), getHeight(), BufferedImage.TYPE_INT_ARGB);

      Graphics2D context = image.createGraphics();

      context.setPaint(getBackground());

      context.fillRect(0, 0, image.getWidth(), image.getHeight());

      draw(context);

      ImageIO.write(image, format, new File(path));

    } catch (IOException e) {

      System.err.println("There was an error trying to create the DrawingPanel image file");

      return false;

    }

    return true;

  }

}