ImgUtil的sliceByRowsAndCols背景无法透明问题

CHANGELOG.md

@@ -2,7 +2,7 @@
 # 🚀Changelog
 
 -------------------------------------------------------------------------------------------------------------
-# 5.8.23(2023-10-25)
+# 5.8.23(2023-10-27)
 
 ### 🐣新特性
 * 【json  】      改进TemporalAccessorSerializer支持dayOfMonth和month枚举名（issue#I82AM8@Gitee）
@@ -21,6 +21,7 @@
 * 【core  】      修复DataSize.parse(size)不支持空格问题（issue#I88Z4Z@Gitee）
 * 【http  】      修复SimpleServer在添加的HttpFilter中有获取请求参数时报错问题（issue#3343@Github）
 * 【http  】      修复options请求无响应体问题
+* 【core  】      ImgUtil的sliceByRowsAndCols背景无法透明问题（issue#3347@Gitee）
 
 -------------------------------------------------------------------------------------------------------------
 # 5.8.22(2023-09-13)

hutool-core/src/main/java/cn/hutool/core/img/Img.java

@@ -133,7 +133,7 @@ public class Img implements Serializable {
 	 * @return Img
 	 */
 	public static Img from(Image image) {
-		return new Img(ImgUtil.toBufferedImage(image));
+		return new Img(ImgUtil.castToBufferedImage(image, ImgUtil.IMAGE_TYPE_JPG));
 	}
 
 	/**

hutool-core/src/main/java/cn/hutool/core/img/ImgUtil.java

@@ -455,11 +455,7 @@ public class ImgUtil {
 	 * @param cols         目标切片列数。默认2，必须是范围 [1, 20] 之内
 	 */
 	public static void sliceByRowsAndCols(File srcImageFile, File destDir, String format, int rows, int cols) {
-		try {
+		sliceByRowsAndCols(read(srcImageFile), destDir, format, rows, cols);
-			sliceByRowsAndCols(ImageIO.read(srcImageFile), destDir, format, rows, cols);
-		} catch (IOException e) {
-			throw new IORuntimeException(e);
-		}
 	}
 
 	/**
@@ -491,7 +487,6 @@ public class ImgUtil {
 			throw new IllegalArgumentException("Destination Dir must be a Directory !");
 		}
 
-		try {
 		if (rows <= 0 || rows > 20) {
 			rows = 2; // 切片行数
 		}
@@ -499,9 +494,8 @@ public class ImgUtil {
 			cols = 2; // 切片列数
 		}
 		// 读取源图像
-			final BufferedImage bi = toBufferedImage(srcImage);
+		int srcWidth = srcImage.getWidth(null); // 源图宽度
-			int srcWidth = bi.getWidth(); // 源图宽度
+		int srcHeight = srcImage.getHeight(null); // 源图高度
-			int srcHeight = bi.getHeight(); // 源图高度
 
 		int destWidth = NumberUtil.partValue(srcWidth, cols); // 每张切片的宽度
 		int destHeight = NumberUtil.partValue(srcHeight, rows); // 每张切片的高度
@@ -510,14 +504,11 @@ public class ImgUtil {
 		Image tag;
 		for (int i = 0; i < rows; i++) {
 			for (int j = 0; j < cols; j++) {
-					tag = cut(bi, new Rectangle(j * destWidth, i * destHeight, destWidth, destHeight));
+				tag = cut(srcImage, new Rectangle(j * destWidth, i * destHeight, destWidth, destHeight));
 				// 输出为文件
-					ImageIO.write(toRenderedImage(tag), format, new File(destDir, "_r" + i + "_c" + j + "." + format));
+				write(tag, new File(destDir, "_r" + i + "_c" + j + "." + format));
 			}
 		}
-		} catch (IOException e) {
-			throw new IORuntimeException(e);
-		}
 	}
 
 	// ---------------------------------------------------------------------------------------------------------------------- convert
@@ -573,8 +564,9 @@ public class ImgUtil {
 	 * @since 4.1.14
 	 */
 	public static void convert(Image srcImage, String formatName, ImageOutputStream destImageStream, boolean isSrcPng) {
+		final BufferedImage src = toBufferedImage(srcImage, isSrcPng ? BufferedImage.TYPE_INT_ARGB : BufferedImage.TYPE_INT_RGB);
 		try {
-			ImageIO.write(isSrcPng ? copyImage(srcImage, BufferedImage.TYPE_INT_RGB) : toBufferedImage(srcImage), formatName, destImageStream);
+			ImageIO.write(src, formatName, destImageStream);
 		} catch (IOException e) {
 			throw new IORuntimeException(e);
 		}
@@ -1157,13 +1149,11 @@ public class ImgUtil {
 	 * @param img {@link Image}
 	 * @return {@link BufferedImage}
 	 * @since 4.3.2
+	 * @deprecated 改用 {@link #castToRenderedImage(Image, String)}
 	 */
+	@Deprecated
 	public static RenderedImage toRenderedImage(Image img) {
-		if (img instanceof RenderedImage) {
+		return castToRenderedImage(img, IMAGE_TYPE_JPG);
-			return (RenderedImage) img;
-		}
-
-		return copyImage(img, BufferedImage.TYPE_INT_RGB);
 	}
 
 	/**
@@ -1172,13 +1162,44 @@ public class ImgUtil {
 	 *
 	 * @param img {@link Image}
 	 * @return {@link BufferedImage}
+	 * @deprecated 改用 {@link #castToBufferedImage(Image, String)}
 	 */
+	@Deprecated
 	public static BufferedImage toBufferedImage(Image img) {
+		return castToBufferedImage(img, IMAGE_TYPE_JPG);
+	}
+
+	/**
+	 * {@link Image} 转 {@link RenderedImage}<br>
+	 * 首先尝试强转，否则新建一个{@link BufferedImage}后重新绘制，使用 {@link BufferedImage#TYPE_INT_RGB} 模式。
+	 *
+	 * @param img {@link Image}
+	 * @param imageType 目标图片类型，例如jpg或png等
+	 * @return {@link BufferedImage}
+	 * @since 4.3.2
+	 */
+	public static RenderedImage castToRenderedImage(final Image img, final String imageType) {
+		if (img instanceof RenderedImage) {
+			return (RenderedImage) img;
+		}
+
+		return toBufferedImage(img, imageType);
+	}
+
+	/**
+	 * {@link Image} 转 {@link BufferedImage}<br>
+	 * 首先尝试强转，否则新建一个{@link BufferedImage}后重新绘制，使用 imageType 模式
+	 *
+	 * @param img {@link Image}
+	 * @param imageType 目标图片类型，例如jpg或png等
+	 * @return {@link BufferedImage}
+	 */
+	public static BufferedImage castToBufferedImage(final Image img, final String imageType) {
 		if (img instanceof BufferedImage) {
 			return (BufferedImage) img;
 		}
 
-		return copyImage(img, BufferedImage.TYPE_INT_RGB);
+		return toBufferedImage(img, imageType);
 	}
 
 	/**
@@ -1687,7 +1708,7 @@ public class ImgUtil {
 		}
 
 		writer.setOutput(output);
-		final RenderedImage renderedImage = toRenderedImage(image);
+		final RenderedImage renderedImage = castToRenderedImage(image, IMAGE_TYPE_JPG);
 		// 设置质量
 		ImageWriteParam imgWriteParams = null;
 		if (quality > 0 && quality < 1) {

hutool-core/src/test/java/cn/hutool/core/img/ImgUtilTest.java

@@ -48,7 +48,9 @@ public class ImgUtilTest {
 	@Test
 	@Ignore
 	public void cutTest() {
-		ImgUtil.cut(FileUtil.file("d:/face.jpg"), FileUtil.file("d:/face_result.jpg"), new Rectangle(200, 200, 100, 100));
+		ImgUtil.cut(FileUtil.file("d:/test/hutool.png"),
+			FileUtil.file("d:/test/result.png"),
+			new Rectangle(0, 0, 400, 240));
 	}
 
 	@Test
@@ -92,6 +94,14 @@ public class ImgUtilTest {
 		ImgUtil.sliceByRowsAndCols(FileUtil.file("d:/temp/2.png"), FileUtil.file("d:/temp/slice/png"),ImgUtil.IMAGE_TYPE_PNG, 1, 5);
 	}
 
+	@Test
+	@Ignore
+	public void sliceByRowsAndColsTest2() {
+		ImgUtil.sliceByRowsAndCols(
+			FileUtil.file("d:/test/hutool.png"),
+			FileUtil.file("d:/test/dest"), ImgUtil.IMAGE_TYPE_PNG, 1, 5);
+	}
+
 	@Test
 	@Ignore
 	public void convertTest() {