基于MIDP2.0实现图片的缩放功能[1]

作者：mingjava  文章来源：http://www.j2medev.com/Article/ShowArticle.asp?ArticleID=144

以前在SUN的论坛看到过关于图片缩放的处理，是基于MIDP2.0实现的。今天看到有网友在问这个问题，因此去翻了一下以前的帖子找到了源代码，自己写了一个测试程序验证了一下效果还算可以。希望可以解这位网友的燃眉之急。

    源代码如下：

package com.j2medev.image;

import javax.microedition.lcdui.*;

public class ImageUtil
{

    // fixed point constants
    private static final int FP_SHIFT = 13;

    private static final int FP_ONE = 1 << FP_SHIFT;

    private static final int FP_HALF = 1 << (FP_SHIFT - 1);

    // resampling modes - valid values for the mode parameter of resizeImage()
    // any other value will default to MODE_BOX_FILTER because of the way the
    // conditionals are set in resizeImage()
    public static final int MODE_POINT_SAMPLE = 0;

    public static final int MODE_BOX_FILTER = 1;

    /**
     * getPixels Wrapper for pixel grabbing techniques. I separated this step
     * into it's own function so that other APIs (Nokia, Motorola, Siemens,
     * etc.) can easily substitute the MIDP 2.0 API (Image.getRGB()).
     *
     * @param src
     *            The source image whose pixels we are grabbing.
     * @return An int array containing the pixels in 32 bit ARGB format.
     */
    int[] getPixels(Image src)
    {
        int w = src.getWidth();
        int h = src.getHeight();
        int[] pixels = new int[w * h];
        src.getRGB(pixels, 0, w, 0, 0, w, h);
        return pixels;
    }

    /**
     * drawPixels Wrapper for pixel drawing function. I separated this step into
     * it's own function so that other APIs (Nokia, Motorola, Siemens, etc.) can
     * easily substitute the MIDP 2.0 API (Image.createRGBImage()).
     *
     * @param pixels
     *            int array containing the pixels in 32 bit ARGB format.
     * @param w
     *            The width of the image to be created.
     * @param h
     *            The height of the image to be created. This parameter is
     *            actually superfluous, because it must equal pixels.length / w.
     * @return The image created from the pixel array.
     */
    Image drawPixels(int[] pixels, int w, int h)
    {
        return Image.createRGBImage(pixels, w, h, true);
    }