c#/vb.net 为 pdf 添加图片水印-凯发线上登陆下载网址

pm> install-package spire.pdf

using spire.pdf;
using system.drawing;
namespace addimagewatermark
{
    class program
    {
        static void main(string[] args)
        {
            //创建一个pdfdocument对象
            pdfdocument document = new pdfdocument();
            //加载示例pdf文档
            document.loadfromfile(@"c:\users\administrator\desktop\sample.pdf");
            //加载图片
            image image = image.fromfile(@"c:\users\administrator\desktop\logo.png");
            //获取图片宽度和高度
            int imgwidth = image.width;
            int imgheight = image.height;
            //遍历页面
            for (int i = 0; i < document.pages.count; i  )
            {
                //获取页面宽度和高度
                float pagewidth = document.pages[i].actualsize.width;
                float pageheight = document.pages[i].actualsize.height;
                //设置背景不透明度
                document.pages[i].backgroudopacity = 0.3f;
                //设置当前页面的背景图片
                document.pages[i].backgroundimage = image;
                //将背景图片置于页面中央
                rectangle rect = new rectangle((int)(pagewidth - imgwidth) / 2, (int)(pageheight - imgheight) / 2, imgwidth, imgheight);
                document.pages[i].backgroundregion = rect;
            }
            //保存文档
            document.savetofile("addimagewatermark.pdf");
            document.close();
        }
    }
}

imports spire.pdf
imports system.drawing
 
namespace addimagewatermark
    class program
        shared  sub main(byval args() as string)
            '创建一个pdfdocument对象
            dim document as pdfdocument =  new pdfdocument() 
 
            '加载示例pdf文档
            document.loadfromfile("c:\users\administrator\desktop\sample.pdf")
 
            '加载图片
            dim image as image =  image.fromfile("c:\users\administrator\desktop\logo.png") 
 
            '获取图片宽度和高度
            dim imgwidth as integer =  image.width 
            dim imgheight as integer =  image.height 
 
            '遍历页面
            dim i as integer
            for  i = 0 to  document.pages.count- 1  step  i   1
                '获取页面宽度和高度
                dim pagewidth as single =  document.pages(i).actualsize.width 
                dim pageheight as single =  document.pages(i).actualsize.height 
 
                '设置背景不透明度
                document.pages(i).backgroudopacity = 0.3f
 
                '设置当前页面的背景图片
                document.pages(i).backgroundimage = image
 
                '将背景图片置于页面中央
                dim rect as rectangle =  new rectangle(ctype((pagewidth - imgwidth) / 2,(integer)(pageheight - imgheight) / 2,imgwidth,imgheight, integer)) 
                document.pages(i).backgroundregion = rect
            next
            '保存文档
            document.savetofile("addimagewatermark.pdf")
            document.close()
        end sub
    end class
end namespace