TextBubbleBorder.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.components.borders;

import net.bither.viewsystem.components.ImageDecorator;

import javax.swing.border.AbstractBorder;
import java.awt.*;
import java.awt.geom.Area;
import java.awt.geom.RoundRectangle2D;

/**
 * <p>Border to provide the following to panels:</p>
 * <ul>
 * <li>Rounded, colored border with variable thickness</li>
 * </ul>
 * <p>Adapted from <a href="http://stackoverflow.com/a/16909994/396747">this Stack Overflow answer</a></p>
 *
 * @since 0.0.1
 */
public class TextBubbleBorder extends AbstractBorder {

    /**
     * The border color
     */
    private final Color color;

    /**
     * The border thickness
     */
    private final int thickness;

    /**
     * The border radii
     */
    private final int radii;

    /**
     * The "speech pointer"
     */
    private final int pointerSize;

    /**
     * The positioning of the "speech pointer"
     */
    private final boolean pointerLeft;

    private final Insets insets;

    private final BasicStroke stroke;

    private final int strokePad;

    private final RenderingHints hints;

    /**
     * <p>A default rounded panel with no pointer</p>
     *
     * @param color The color
     */
    public TextBubbleBorder(Color color) {

        this(color, 1, 10, 0, true);

    }

    /**
     * <p>A customised text bubble with no pointer</p>
     *
     * @param color     The color
     * @param thickness The thickness (in px)
     * @param radii     The radius to use for each corner (default 10)
     */
    public TextBubbleBorder(Color color, int thickness, int radii) {

        this(color, thickness, radii, 0, true);

    }

    /**
     * <p>A customised text bubble with pointer defined</p>
     *
     * @param color       The color
     * @param thickness   The thickness (in px)
     * @param radii       The radius to use for each corner (default 10)
     * @param pointerSize The pointer size
     * @param pointerLeft True if the pointer is on the left
     */
    public TextBubbleBorder(Color color, int thickness, int radii, int pointerSize, boolean pointerLeft) {

        this.pointerLeft = pointerLeft;

        this.thickness = thickness;
        this.radii = radii;
        this.pointerSize = pointerSize;
        this.color = color;

        this.stroke = new BasicStroke(thickness);
        this.strokePad = thickness / 2;

        this.hints = new RenderingHints(ImageDecorator.smoothRenderingHints());

        // Top and bottom padding must adjust to allow for single line panels (e.g. alerts)
        // and also compromise for text fields and text areas. A good value is 6px.
        int topPad = 6;
        int bottomPad = Math.max(topPad, pointerSize + strokePad);

        insets = new Insets(topPad, 8, bottomPad, 8);

    }

    @Override
    public Insets getBorderInsets(Component c) {
        return insets;
    }

    @Override
    public Insets getBorderInsets(Component c, Insets insets) {
        return getBorderInsets(c);
    }

    @Override
    public void paintBorder(Component c, Graphics g, int x, int y, int width, int height) {

        // Work out the lowest inside line of the bubble
        int bottomLineY = height - thickness - pointerSize - 1;

        // Draw the rounded bubble border with a few tweaks for text fields and areas
        RoundRectangle2D.Double bubble = new RoundRectangle2D.Double(
                strokePad + 2,
                strokePad + 2,
                width - thickness - strokePad - 3,
                bottomLineY - 2,
                radii,
                radii);

        Area area = new Area(bubble);

        // Should the "speech pointer" polygon be included?
        if (pointerSize > 0) {
            Polygon pointer = new Polygon();
            int pointerPad = 4;

            // Place on left
            if (pointerLeft) {
                // Left point
                pointer.addPoint(strokePad + radii + pointerPad, bottomLineY);
                // Right point
                pointer.addPoint(strokePad + radii + pointerPad + pointerSize, bottomLineY);
                // Bottom point
                pointer.addPoint(strokePad + radii + pointerPad + (pointerSize / 2), height - strokePad);
            } else {
                // Left point
                pointer.addPoint(width - (strokePad + radii + pointerPad), bottomLineY);
                // Right point
                pointer.addPoint(width - (strokePad + radii + pointerPad + pointerSize), bottomLineY);
                // Bottom point
                pointer.addPoint(width - (strokePad + radii + pointerPad + (pointerSize / 2)), height - strokePad);
            }
            area.add(new Area(pointer));
        }

        // Get the 2D graphics context
        Graphics2D g2 = (Graphics2D) g;
        g2.setRenderingHints(hints);

        // Paint the background color of the parent everywhere
        // outside the clip of the text bubble
        Component parent = c.getParent();
        if (parent != null) {

            Color bg = parent.getBackground();
            Rectangle rect = new Rectangle(0, 0, width, height);

            Area borderRegion = new Area(rect);
            borderRegion.subtract(area);

            g2.setClip(borderRegion);
            g2.setColor(bg);
            g2.fillRect(0, 0, width, height);
            g2.setClip(null);

        }

        // Set the border color
        g2.setColor(color);
        g2.setStroke(stroke);
        g2.draw(area);

    }
}