Java Swing Icon scaleDown(Icon icon, int maxWidth, int maxHeight)

Description

scale Down

License

Apache License

Declaration

public static Icon scaleDown(Icon icon, int maxWidth, int maxHeight)

Method Source Code

//package com.java2s;
//License from project: Apache License 

import javax.swing.*;

import java.awt.*;

import java.awt.image.BufferedImage;

public class Main {
    public static Icon scaleDown(Icon icon, int maxWidth, int maxHeight) {
        int w = icon.getIconWidth();
        int h = icon.getIconHeight();
        if (maxWidth > w && maxHeight > h) {
            return icon;
        }//from w w  w.j  ava2s.c  om

        BufferedImage image = new BufferedImage(w, h, BufferedImage.TYPE_INT_ARGB);
        Graphics2D g2d = (Graphics2D) image.getGraphics();
        icon.paintIcon(null, g2d, 0, 0);
        g2d.dispose();

        double hRatio = (double) maxWidth / (double) w;
        double vRatio = (double) maxHeight / (double) h;
        double ratio = Math.min(hRatio, vRatio);

        double targetWidth = ratio * w;
        double targetHeight = ratio * h;

        final BufferedImage scaledImage = getScaledInstance(image, (int) targetWidth, (int) targetHeight,
                RenderingHints.VALUE_INTERPOLATION_BILINEAR, true);

        return new Icon() {
            public void paintIcon(Component component, Graphics graphics, int x, int y) {
                graphics.drawImage(scaledImage, x, y, null);
            }

            public int getIconWidth() {
                return scaledImage.getWidth();
            }

            public int getIconHeight() {
                return scaledImage.getHeight();
            }
        };
    }

    /**
     * From http://today.java.net/pub/a/today/2007/04/03/perils-of-image-getscaledinstance.html
     * Convenience method that returns a scaled instance of the
     * provided {@code BufferedImage}.
     *
     * @param img           the original image to be scaled
     * @param targetWidth   the desired width of the scaled instance,
     *                      in pixels
     * @param targetHeight  the desired height of the scaled instance,
     *                      in pixels
     * @param hint          one of the rendering hints that corresponds to
     *                      {@code RenderingHints.KEY_INTERPOLATION} (e.g.
     *                      {@code RenderingHints.VALUE_INTERPOLATION_NEAREST_NEIGHBOR},
     *                      {@code RenderingHints.VALUE_INTERPOLATION_BILINEAR},
     *                      {@code RenderingHints.VALUE_INTERPOLATION_BICUBIC})
     * @param higherQuality if true, this method will use a multi-step
     *                      scaling technique that provides higher quality than the usual
     *                      one-step technique (only useful in downscaling cases, where
     *                      {@code targetWidth} or {@code targetHeight} is
     *                      smaller than the original dimensions, and generally only when
     *                      the {@code BILINEAR} hint is specified)
     * @return a scaled version of the original {@code BufferedImage}
     */
    private static BufferedImage getScaledInstance(BufferedImage img, int targetWidth, int targetHeight,
            Object hint, boolean higherQuality) {
        int type = (img.getTransparency() == Transparency.OPAQUE) ? BufferedImage.TYPE_INT_RGB
                : BufferedImage.TYPE_INT_ARGB;
        BufferedImage ret = img;
        int w, h;
        if (higherQuality) {
            // Use multi-step technique: start with original size, then
            // scale down in multiple passes with drawImage()
            // until the target size is reached
            w = img.getWidth();
            h = img.getHeight();
        } else {
            // Use one-step technique: scale directly from original
            // size to target size with a single drawImage() call
            w = targetWidth;
            h = targetHeight;
        }

        do {
            if (higherQuality && w > targetWidth) {
                w /= 2;
                if (w < targetWidth) {
                    w = targetWidth;
                }
            }

            if (higherQuality && h > targetHeight) {
                h /= 2;
                if (h < targetHeight) {
                    h = targetHeight;
                }
            }

            BufferedImage tmp = new BufferedImage(w, h, type);
            Graphics2D g2 = tmp.createGraphics();
            g2.setRenderingHint(RenderingHints.KEY_INTERPOLATION, hint);
            g2.drawImage(ret, 0, 0, w, h, null);
            g2.dispose();

            ret = tmp;
        } while (w > targetWidth || h > targetHeight);

        return ret;
    }
}

Java Swing Icon scaleDown(Icon icon, int maxWidth, int maxHeight)

Description

License

Declaration

Method Source Code

Related