指定压缩后图片的背景色

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

@@ -60,6 +60,10 @@ public class Img implements Serializable {
 	 * 图片输出质量，用于压缩
 	 */
 	private float quality = -1;
+	/**
+	 * 图片背景色
+	 */
+	private Color backgroundColor;
 
 	/**
 	 * 从Path读取图片并开始处理
@@ -216,6 +220,17 @@ public class Img implements Serializable {
 		return this;
 	}
 
+	/**
+	 * 设置图片的背景色
+	 *
+	 * @param backgroundColor{@link Color} 背景色
+	 * @return this
+	 */
+	public Img setBackgroundColor(Color backgroundColor) {
+		this.backgroundColor = backgroundColor;
+		return this;
+	}
+
 	/**
 	 * 缩放图像（按比例缩放）
 	 *
@@ -709,7 +724,7 @@ public class Img implements Serializable {
 		final Image targetImage = (null == this.targetImage) ? this.srcImage : this.targetImage;
 		Assert.notNull(targetImage, "Target image is null !");
 
-		return ImgUtil.write(targetImage, this.targetImageType, targetImageStream, this.quality);
+		return ImgUtil.write(targetImage, this.targetImageType, targetImageStream, this.quality, this.backgroundColor);
 	}
 
 	/**

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

@@ -1166,10 +1166,25 @@ public class ImgUtil {
 	 * @since 4.3.2
 	 */
 	public static BufferedImage toBufferedImage(Image image, String imageType) {
+		return toBufferedImage(image, imageType, null);
+	}
+
+	/**
+	 * {@link Image} 转 {@link BufferedImage}<br>
+	 * 如果源图片的RGB模式与目标模式一致，则直接转换，否则重新绘制<br>
+	 * 默认的，png图片使用 {@link BufferedImage#TYPE_INT_ARGB}模式，其它使用 {@link BufferedImage#TYPE_INT_RGB} 模式
+	 *
+	 * @param image     		{@link Image}
+	 * @param imageType 		目标图片类型，例如jpg或png等
+	 * @param backgroundColor	背景色{@link Color}
+	 * @return {@link BufferedImage}
+	 * @since 4.3.2
+	 */
+	public static BufferedImage toBufferedImage(Image image, String imageType, Color backgroundColor) {
 		final int type = IMAGE_TYPE_PNG.equalsIgnoreCase(imageType)
 				? BufferedImage.TYPE_INT_ARGB
 				: BufferedImage.TYPE_INT_RGB;
-		return toBufferedImage(image, type);
+		return toBufferedImage(image, type, backgroundColor);
 	}
 
 	/**
@@ -1195,6 +1210,30 @@ public class ImgUtil {
 		return bufferedImage;
 	}
 
+	/**
+	 * {@link Image} 转 {@link BufferedImage}<br>
+	 * 如果源图片的RGB模式与目标模式一致，则直接转换，否则重新绘制
+	 *
+	 * @param image     {@link Image}
+	 * @param imageType 目标图片类型，{@link BufferedImage}中的常量，例如黑白等
+	 * @param backgroundColor	背景色{@link Color}
+	 * @return {@link BufferedImage}
+	 * @since 5.4.7
+	 */
+	public static BufferedImage toBufferedImage(Image image, int imageType, Color backgroundColor) {
+		BufferedImage bufferedImage;
+		if (image instanceof BufferedImage) {
+			bufferedImage = (BufferedImage) image;
+			if (imageType != bufferedImage.getType()) {
+				bufferedImage = copyImage(image, imageType, backgroundColor);
+			}
+			return bufferedImage;
+		}
+
+		bufferedImage = copyImage(image, imageType, backgroundColor);
+		return bufferedImage;
+	}
+
 	/**
 	 * 将已有Image复制新的一份出来
 	 *
@@ -1562,11 +1601,27 @@ public class ImgUtil {
 	 * @since 4.3.2
 	 */
 	public static boolean write(Image image, String imageType, ImageOutputStream destImageStream, float quality) throws IORuntimeException {
+		return write(image, imageType, destImageStream, quality, null);
+	}
+
+	/**
+	 * 写出图像为指定格式
+	 *
+	 * @param image           {@link Image}
+	 * @param imageType       图片类型（图片扩展名）
+	 * @param destImageStream 写出到的目标流
+	 * @param quality         质量，数字为0~1（不包括0和1）表示质量压缩比，除此数字外设置表示不压缩
+	 * @param backgroundColor	背景色{@link Color}
+	 * @return 是否成功写出，如果返回false表示未找到合适的Writer
+	 * @throws IORuntimeException IO异常
+	 * @since 4.3.2
+	 */
+	public static boolean write(Image image, String imageType, ImageOutputStream destImageStream, float quality, Color backgroundColor) throws IORuntimeException {
 		if (StrUtil.isBlank(imageType)) {
 			imageType = IMAGE_TYPE_JPG;
 		}
 
-		final BufferedImage bufferedImage = toBufferedImage(image, imageType);
+		final BufferedImage bufferedImage = toBufferedImage(image, imageType, backgroundColor);
 		final ImageWriter writer = getWriter(bufferedImage, imageType);
 		return write(bufferedImage, writer, destImageStream, quality);
 	}

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

@@ -26,6 +26,15 @@ public class ImgTest {
 		Img.from(FileUtil.file("f:/test/4347273249269e3fb272341acc42d4e.jpg")).setQuality(0.8).write(FileUtil.file("f:/test/test_dest.jpg"));
 	}
 
+	@Test
+	@Ignore
+	public void compressWithBackgroundColorTest() {
+		Img.from(FileUtil.file("D:/test/before_compress.png"))
+				.setBackgroundColor(Color.WHITE)
+				.setQuality(0.8)
+				.write(FileUtil.file("D:/test/after_compress.jpg"));
+	}
+
 	@Test
 	@Ignore
 	public void writeTest() {