Simplifies creating and coordinating JFXPanels

AppletFX.java

/*
 * Copyright 2017, UniquePassive <https://github.com/uniquepassive>
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */
package com.appletfx;

import com.sun.javafx.application.PlatformImpl;
import javafx.collections.ObservableList;
import javafx.embed.swing.JFXPanel;
import javafx.scene.Scene;
import javafx.scene.layout.Pane;

import java.util.ArrayList;
import java.util.List;

public class AppletFX {

	private static final Object SYNC_OBJECT = new Object();

	private static List<JFXPanel> panels = new ArrayList<>();

	private static String stylesheetPath;

	/**
	 * Creates a panel that makes use of the global stylesheet.
	 * <p>
	 * {@link AppletFX#setGlobalStylesheet(String)}
	 * must have been called before calling this method.
	 *
	 * @return a new JFXPanel that uses the global stylesheet
	 */
	public static JFXPanel createPanel() {
		if (stylesheetPath == null) {
			throw new IllegalStateException("A global stylesheet must be set before creating a panel");
		}

		JFXPanel panel = new JFXPanel();

		PlatformImpl.runAndWait(() -> {
			synchronized (SYNC_OBJECT) {
				Scene scene = new Scene(new Pane());
				scene.getStylesheets().add(stylesheetPath);
				panel.setScene(scene);

				panels.add(panel);
			}
		});

		return panel;
	}

	/**
	 * Sets the global stylesheet that is
	 * applied to all new and existing panels.
	 *
	 * @param path the file path to the stylesheet
	 */
	public static void setGlobalStylesheet(String path) {
		synchronized (SYNC_OBJECT) {
			String previousStyleSheet = stylesheetPath;
			stylesheetPath = path;

			for (JFXPanel panel : panels) {
				ObservableList<String> stylesheets = panel
						.getScene()
						.getStylesheets();

				int index = stylesheets.indexOf(previousStyleSheet);

				if (index != -1 && stylesheets.size() > index) {
					stylesheets.set(index, path);
				}
			}
		}
	}

	/**
	 * @return the global stylesheet file path,
	 *         or {@code null} if it hasn't been set
	 */
	public static String getGlobalStylesheet() {
		return stylesheetPath;
	}

	/**
	 * Runs code on the JavaFX Application Thread,
	 * and then updates the panel's scene so that
	 * it gets resized in the case that components
	 * have been added or removed from the panel.
	 *
	 * @param panel the panel that the Runnable operates on.
	 *              This parameter may be null.
	 * @param runnable the Runnable whose run method will be 
	 *                 executed on the JavaFX Application Thread
	 */
	public static void runAndWait(JFXPanel panel, Runnable runnable) {
		PlatformImpl.runAndWait(runnable);

		/*
			Hacky way of making it so the
			panel will resize when components
			have been added or removed.
		 */
		if (panel != null) {
			Scene scene = panel.getScene();
			panel.setScene(null);
			panel.setScene(scene);
		}
	}
}