Java之png圖檔工具類

import java.awt.Graphics2D;
import java.awt.Image;
import java.awt.Transparency;
import java.awt.image.BufferedImage;
import java.io.File;
import javax.imageio.ImageIO;

/**
 * 圖檔工具類
 */
public class ImageUtil
{

	/**
	 * 裁剪PNG圖檔工具類
	 *
	 * @param fromFile     源檔案
	 * @param toFile       裁剪後的檔案
	 * @param outputWidth  裁剪寬度
	 * @param outputHeight 裁剪高度
	 * @param proportion   是否是等比縮放
	 */
	public static void resizePng(File fromFile, File toFile, int outputWidth, int outputHeight, boolean proportion)
	{
		try
		{
			BufferedImage bi2 = ImageIO.read(fromFile);
			int newWidth;
			int newHeight;
			// 判斷是否是等比縮放
			if (proportion)
			{
				// 為等比縮放計算輸出的圖檔寬度及高度
				double rate1 = ((double) bi2.getWidth(null)) / (double) outputWidth + 0.1;
				double rate2 = ((double) bi2.getHeight(null)) / (double) outputHeight + 0.1;
				// 根據縮放比率大的進行縮放控制
				double rate = rate1 < rate2 ? rate1 : rate2;
				newWidth = (int) (((double) bi2.getWidth(null)) / rate);
				newHeight = (int) (((double) bi2.getHeight(null)) / rate);
			} else
			{
				newWidth = outputWidth; // 輸出的圖檔寬度
				newHeight = outputHeight; // 輸出的圖檔高度
			}
			BufferedImage to = new BufferedImage(newWidth, newHeight, BufferedImage.TYPE_INT_RGB);
			Graphics2D g2d = to.createGraphics();
			to = g2d.getDeviceConfiguration().createCompatibleImage(newWidth, newHeight, Transparency.TRANSLUCENT);
			g2d.dispose();
			g2d = to.createGraphics();
			@SuppressWarnings("static-access")
			Image from = bi2.getScaledInstance(newWidth, newHeight, bi2.SCALE_AREA_AVERAGING);
			g2d.drawImage(from, 0, 0, null);
			g2d.dispose();
			ImageIO.write(to, "png", toFile);
		} catch (Exception e)
		{
			e.printStackTrace();
		}
	}

	/**
	 * 測試
	 */
	public static void main(String[] args) throws Exception
	{
		File fromFile = new File("c:/a.png");
		File toFile = new File("c:/b.png");
		resizePng(fromFile, toFile, 31, 32, false);
	}
}
           

轉載：https://gitee.com/northstar888/codes/u638g2kszn147wvipdlhx76