LightBoxPanel.java

/*
 *
 *  Copyright 2014 http://Bither.net
 *
 *  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 net.bither.viewsystem.panels;

import com.google.common.base.Preconditions;
import net.bither.Bither;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import javax.swing.*;
import java.awt.*;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;

/**
 * <p>Component to provide the following to UI:</p>
 * <ul>
 * <li>Provision of a light box effect where the background is dimmed</li>
 * </ul>
 *
 * @since 0.0.1
 */
public class LightBoxPanel extends JPanel {

    private final JPanel screenPanel;
    private static final Logger log = LoggerFactory.getLogger(LightBoxPanel.class);

    /**
     * @param screenPanel The panel containing the light box components (e.g. a wizard screen panel)
     * @param layer       The layer which to place the panel (JLayeredPane.MODAL_LAYER for wizards, DRAG_LAYER for popovers within wizards)
     */
    public LightBoxPanel(JPanel screenPanel, Integer layer) {

        Preconditions.checkNotNull(screenPanel, "'panel' must be present");

        Preconditions.checkState(screenPanel.getWidth() > 0, "'width' must be greater than zero");
        Preconditions.checkState(screenPanel.getHeight() > 0, "'height' must be greater than zero");

        this.screenPanel = screenPanel;

        // Ensure we set the opacity (platform dependent)
        setOpaque(false);

        // Ensure we are visible
        setVisible(true);

        // Ensure this panel covers all the available frame area
        setSize(Bither.getMainFrame().getWidth() + 100, Bither.getMainFrame().getHeight() + 100);

        // Prevent mouse events reaching through the darkened border
        addMouseListener(new ModalMouseListener());

        // Add this panel to the frame's layered panel as the palette layer (directly above the default)
        if (JLayeredPane.MODAL_LAYER.equals(layer)) {
            Bither.getMainFrame().getLayeredPane().add(this, JLayeredPane.PALETTE_LAYER);
        } else {
            Bither.getMainFrame().getLayeredPane().add(this, JLayeredPane.POPUP_LAYER);
        }

        // Provide a starting position
        calculatePosition();

        // Add the light box panel to the frame
        Bither.getMainFrame().getLayeredPane().add(screenPanel, layer);


    }

    /**
     * <p>Calculate the position of the center panel</p>
     */
    private void calculatePosition() {

        int currentFrameWidth = Bither.getMainFrame().getWidth();
        int currentFrameHeight = Bither.getMainFrame().getHeight();

        // Ensure this panel covers all the available frame area allowing for fast dragging
        setSize(currentFrameWidth * 2, currentFrameHeight * 2);

        // Center the light box panel in the frame
        int x = (currentFrameWidth - screenPanel.getWidth()) / 2;
        int y = ((currentFrameHeight - screenPanel.getHeight()) / 2) - 10; // The 10 offset is a magic number

        // Avoid any negative values if resizing gets cramped
        x = x < 0 ? 0 : x;
        y = y < 0 ? 0 : y;

        screenPanel.setLocation(x, y);
    }

    /**
     * <p>Close the light box</p>
     * <p/>
     * <p>During handover the dark panel is allowed to remain to give visual continuity</p>
     */
    public void close() {

        Preconditions.checkState(SwingUtilities.isEventDispatchThread(), "Must be on the EDT");

        // NOTE: We cannot remove by reference reliably so this approach is used

        // The light box panels are stacked in visual order therefore the usual index positions are
        // 0: Wizard content panel (JPanel.WizardCardLayout)
        // 1: Dark panel (LightBoxPanel)
        // 2: Main content (JPanel.JRootPane)
        //
        // If a popover is present it is stacked over the light box leading to
        // 0: Popover content panel (RoundedPanel)
        // 1: Popover dark panel (LightBoxPanel)
        // 2: Wizard content panel (JPanel.WizardCardLayout)
        // 3: Dark panel (LightBoxPanel)
        // 4: Main content (JPanel.JRootPane)

        JLayeredPane layeredPane = Bither.getMainFrame().getLayeredPane();

        Component[] components = layeredPane.getComponents();

        if (log.isDebugEnabled()) {
            for (int i = 0; i < components.length; i++) {
                //log.debug("[{}]: {}", i, components[i].getClass().getSimpleName());
            }
        }

        boolean popoverPresent = components.length > 3;

        // Check for tooltips
        if (components.length == 4 || components.length == 6) {

            layeredPane.remove(0);


        }

        if (components.length > 2 && components.length < 7) {

            // Remove the dark panel
            layeredPane.remove(1);

            // Remove the content panel (components will have shuffled)
            layeredPane.remove(0);

            if (popoverPresent) {
                // log.debug("Popover light boxane panel removed from application frame");
            } else {
                // log.debug("Wizard light box panel removed from application frame");
            }
        } else {
            // log.error("Unknown component hierarchy in light box.");
            for (int i = 0; i < components.length; i++) {
                // log.error("[{}]: {}", i, components[i].getClass().getSimpleName());
            }
        }

        // Repaint
        Bither.getMainFrame().validate();
        Bither.getMainFrame().repaint();

    }

    @Override
    protected void paintComponent(Graphics graphics) {

        // Reposition the center panel on the fly
        calculatePosition();

        Graphics2D g = (Graphics2D) graphics;

        // Always use black even for light themes
        g.setPaint(Color.BLACK);

        // Set the opacity
        g.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER, 0.5f));

        // Create the darkened border rectangle (will appear beneath the panel layer)
        g.fillRect(0, 0, Bither.getMainFrame().getWidth(), Bither.getMainFrame().getHeight());

    }

    /**
     * Prevent mouse events reaching through the light box border
     */
    private class ModalMouseListener implements MouseListener {

        @Override
        public void mouseClicked(MouseEvent e) {
            // Do nothing
        }

        @Override
        public void mousePressed(MouseEvent e) {
            // Do nothing
        }

        @Override
        public void mouseReleased(MouseEvent e) {
            // Do nothing
        }

        @Override
        public void mouseEntered(MouseEvent e) {
            // Do nothing
        }

        @Override
        public void mouseExited(MouseEvent e) {
            // Do nothing
        }
    }

}