java中BufferedImage的迷惑坐标系_bufferedimage 坐标-优快云博客

本文链接：https://blog.youkuaiyun.com/XTU_xyx/article/details/129411799

文章讨论了在Java中使用BufferedImage处理图片时遇到的坐标系问题，特别是在添加水印的过程中，需要考虑到坐标方向与预期不同的情况。作者提供了代码示例，说明如何根据源图尺寸调整水印的大小，并使用Thumbnails库进行缩放和添加水印操作，同时强调了不同工具类间坐标系统的一致性问题。

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BufferedImage坐标系问题

操作源图：
我尝试图片上添加水印，由于像素大小不同，所以加水印前需要将水印的像素大小根据被加水印的源图的像素调整：

	public static void imgWatermark(String inFilePath, String waterMarkFilePath, String position, float scale, float opacity, OutputStream out) throws IOException {
        Thumbnails.Builder<File> builder = Thumbnails.of(new File(inFilePath));

        BufferedImage inFileImg = ImageIO.read(new File(inFilePath));
        System.out.println("源图：宽：" + inFileImg.getWidth() + " 高：" + inFileImg.getHeight());
        BufferedImage waterMarkImg = ImageIO.read(new File(waterMarkFilePath));
        //这里BufferedImage坐标系与Thumbnails坐标系x,y相反，所以要反取宽高
        float waterMarkWidth = inFileImg.getHeight() * scale;
        float waterMarkHeight = waterMarkImg.getWidth() * (waterMarkWidth/waterMarkImg.getHeight());
        BufferedImage resizedWaterMark = Thumbnails.of(new File(waterMarkFilePath)).size((int) waterMarkWidth, (int) waterMarkHeight).outputQuality(1.0F).asBufferedImage();

        builder.outputQuality(1.0F).scale(1.0F).watermark(getPositions(position), resizedWaterMark, opacity).toOutputStream(out);
    }