Java ImageIcon paintWithWatermarkHelper(JComponent component, ImageIcon watermark, Graphics g)

Description

A helper function to paint a watermark for a component.

License

Open Source License

Parameter

Parameter	Description
g	a parameter

Declaration

public static void paintWithWatermarkHelper(JComponent component, ImageIcon watermark, Graphics g) 

Method Source Code

//package com.java2s;
import java.awt.AlphaComposite;

import java.awt.Component;
import java.awt.Composite;
import java.awt.Container;

import java.awt.Graphics;
import java.awt.Graphics2D;

import java.awt.Paint;
import java.awt.Rectangle;

import javax.swing.ImageIcon;

import javax.swing.JComponent;

import javax.swing.JViewport;

public class Main {
    /**/* w ww .  j a  v a  2  s  .com*/
     * A helper function to paint a watermark for a component.
     * This should be called in the paintComponent method before calling the super class method.
     * @param g
     */
    public static void paintWithWatermarkHelper(JComponent component, ImageIcon watermark, Graphics g) {
        Graphics2D g2 = (Graphics2D) g;

        Paint oldPaint = g2.getPaint();
        g2.setPaint(component.getBackground());

        try {
            // Fill in the background of the component.
            g2.fillRect(0, 0, component.getWidth(), component.getHeight());

            // Draw the background image, if any.
            if (watermark != null) {

                // draw the image centred in the visible area, and scaled to fit
                Rectangle viewRect = new Rectangle(0, 0, component.getWidth(), component.getHeight());

                Component parent = component.getParent();
                if (parent instanceof JViewport) {
                    JViewport viewport = (JViewport) parent;
                    viewRect = viewport.getViewRect();
                }

                int imageWidth = watermark.getIconWidth();
                int imageHeight = watermark.getIconHeight();

                double xZoom = viewRect.getWidth() / imageWidth;
                double yZoom = viewRect.getHeight() / imageHeight;

                double zoom = Math.min(xZoom, yZoom);

                int drawnWidth = (int) (imageWidth * zoom);
                int drawnHeight = (int) (imageHeight * zoom);

                int x = viewRect.x + (viewRect.width - drawnWidth) / 2;
                int y = viewRect.y + (viewRect.height - drawnHeight) / 2;

                Composite oldComposite = g2.getComposite();

                g2.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER, 0.25f));

                g2.drawImage(watermark.getImage(), x, y, x + drawnWidth, y + drawnHeight, 0, 0, imageWidth,
                        imageHeight, null);

                g2.setComposite(oldComposite);
            }
        } finally {
            g2.setPaint(oldPaint);
        }
    }

    /**
     * Returns the parent component of the component c that has the given type,
     * or <code>null</code> if such parent does not exist. 
     * @param c
     * @param type
     * @return Component
     */
    public static Component getParent(Component c, Class<? extends Container> type) {
        c = c.getParent();
        while (c != null) {
            // assume that they are loaded by the same classloader
            if (c.getClass() == type) {
                return c;
            }
            c = c.getParent();
        }
        return null;
    }
}

Related

1. imageWithBackground(ImageIcon icon, Color colorBg)
2. initImageIcon(Class cl)
3. isValidImg(ImageIcon img)
4. loadJavaInternal(ImageIcon r, Dimension d, boolean noStretch)
5. makeDisabledImage(ImageIcon in)
6. parseImageIcon(Image image)
7. prepareImage(ImageIcon icon, int x, int y)
8. saveImage(ImageIcon picture, String targetfile)
9. setDefaultImageIcons(Window window)