/*
 * Copyright (c) 2002-2007 JGoodies Karsten Lentzsch. All Rights Reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 *  o Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 *
 *  o Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 *
 *  o Neither the name of JGoodies Karsten Lentzsch nor the names of
 *    its contributors may be used to endorse or promote products derived
 *    from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
 * OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
 * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

package com.jgoodies.forms.debug;

import java.awt.Color;
import java.awt.Graphics;

import javax.swing.JPanel;

import com.jgoodies.forms.layout.FormLayout;

/**
 * A panel that paints grid bounds if and only if the panel's layout manager
 * is a {@link FormLayout}. You can tweak the debug paint process by setting
 * a custom grid color, painting optional diagonals and painting the grid
 * in the background or foreground.<p>
 *
 * This class is not intended to be extended. However, it is not
 * marked as <code>final</code> to allow users to subclass it for
 * debugging purposes. In general it is recommended to <em>use</em> JPanel
 * instances, not <em>extend</em> them. You can see this implementation style
 * in the Forms tutorial classes. Rarely there's a need to extend JPanel;
 * for example if you provide a custom behavior for
 * <code>#paintComponent</code> or <code>#updateUI</code>.
 *
 * @author  Karsten Lentzsch
 * @version $Revision$
 *
 * @see     FormDebugUtils
 */
@SuppressWarnings("serial")
public class FormDebugPanel extends JPanel {

    /**
     * The default color used to paint the form's debug grid.
     */
    private static final Color DEFAULT_GRID_COLOR = Color.red;

    /**
     * Specifies whether the grid shall be painted in the background.
     * Is off by default and so the grid is painted in the foreground.
     */
    private boolean paintInBackground;

    /**
     * Specifies whether the container's diagonals should be painted.
     */
    private boolean paintDiagonals;

    /**
     * Holds the color used to paint the debug grid.
     */
    private Color gridColor = DEFAULT_GRID_COLOR;

    // Instance Creation ****************************************************

    /**
     * Constructs a FormDebugPanel with all options turned off.
     */
    public FormDebugPanel() {
        this(null);
    }

    /**
     * Constructs a FormDebugPanel on the given FormLayout instance
     * that paints the grid in the foreground and paints no diagonals.
     *
     * @param layout  the panel's FormLayout instance
     */
    public FormDebugPanel(FormLayout layout) {
        this(layout, false, false);
    }

    /**
     * Constructs a FormDebugPanel on the given FormLayout
     * using the specified settings that are otherwise turned off.
     *
     * @param paintInBackground
     *     true to paint grid lines in the background,
     *     false to paint the grid in the foreground
     * @param paintDiagonals
     *     true to paint diagonals,
     *     false to not paint them
     */
    public FormDebugPanel(boolean paintInBackground, boolean paintDiagonals) {
        this(null, paintInBackground, paintDiagonals);
    }

    /**
     * Constructs a FormDebugPanel on the given FormLayout using
     * the specified settings that are otherwise turned off.
     *
     * @param layout
     *     the panel's FormLayout instance
     * @param paintInBackground
     *     true to paint grid lines in the background,
     *     false to paint the grid in the foreground
     * @param paintDiagonals
     *     true to paint diagonals,
     *     false to not paint them
     */
    public FormDebugPanel(FormLayout layout, boolean paintInBackground,
            boolean paintDiagonals) {
        super(layout);
        setPaintInBackground(paintInBackground);
        setPaintDiagonals(paintDiagonals);
        setGridColor(DEFAULT_GRID_COLOR);
    }

    // Accessors ************************************************************

    /**
     * Specifies to paint in background or foreground.
     *
     * @param b    true to paint in the background, false for the foreground
     */
    public void setPaintInBackground(boolean b) {
        paintInBackground = b;
    }

    /**
     * Enables or disables to paint the panel's diagonals.
     *
     * @param b    true to paint diagonals, false to not paint them
     */
    public void setPaintDiagonals(boolean b) {
        paintDiagonals = b;
    }

    /**
     * Sets the debug grid's color.
     *
     * @param color  the color used to paint the debug grid
     */
    public void setGridColor(Color color) {
        gridColor = color;
    }

    // Painting *************************************************************

    /**
     * Paints the component and - if background painting is enabled - the grid.
     * If foreground painting is enabled, the grid will be painted in
     * <code>#paint</code>.
     *
     * @param g   the Graphics object to paint on
     *
     * @see #paint(Graphics)
     */
    @Override
    protected void paintComponent(Graphics g) {
        super.paintComponent(g);
        if (paintInBackground) {
            paintGrid(g);
        }
    }

    /**
     * Paints the panel. If the panel's layout manager is a FormLayout
     * and foreground painting is enabled, it paints the form's grid lines.
     * If the grid shall be painted in the background, the grid will be
     * painted in <code>#paintComponent</code>.
     *
     * @param g   the Graphics object to paint on
     *
     * @see #paintComponent(Graphics)
     */
    @Override
    public void paint(Graphics g) {
        super.paint(g);
        if (!paintInBackground) {
            paintGrid(g);
        }
    }

    /**
     * Paints the form's grid lines and diagonals.
     *
     * @param g    the Graphics object used to paint
     */
    private void paintGrid(Graphics g) {
        if (!(getLayout() instanceof FormLayout)) {
            return;
        }
        FormLayout.LayoutInfo layoutInfo = FormDebugUtils.getLayoutInfo(this);
        int left = layoutInfo.getX();
        int top = layoutInfo.getY();
        int width = layoutInfo.getWidth();
        int height = layoutInfo.getHeight();

        g.setColor(gridColor);
        // Paint the column bounds.
        for (int columnOrigin : layoutInfo.columnOrigins) {
            g.fillRect(columnOrigin, top, 1, height);
        }

        // Paint the row bounds.
        for (int rowOrigin : layoutInfo.rowOrigins) {
            g.fillRect(left, rowOrigin, width, 1);
        }

        if (paintDiagonals) {
            g.drawLine(left, top, left + width, top + height);
            g.drawLine(left, top + height, left + width, top);
        }
    }

}