C#版本的Aspose.Pdf 资源太难找了，尤其是没有水印的，Aspose.Pdf无水印版下载（10.1），尤其是你在某DN网站上下载的资源基本上测试后都是有水印的，或者就是报强签名的问题，花费了很多积分（这些积分可是实打实的银子啊）下载下来不能使用，想用板砖拍它心都有了。
提示：当前基于 .net framework进行测试的，笔者老项目中正常使用，至于.net core或者.net 5,6,7能否使用，请自行测试。
Aspose.Pdf无水印版下载
这玩意儿你不花钱的话，很难找到最新的无水印版，网上好多打着最新版本的，要么下载不成功，要么不可用，一是不想注册它们网站的用户，二是不想花钱，因此这儿就免费提供了，想下就下呗，你懂的。
下载地址：（Aspose.pdf无水印版下载）
Aspose.pdf 无水印版 (下载946 )
下面的代码收录自网上，并没有完整测试，想来直接用问题不大。
C# PDF转图片
网页上要上传一些证件照,但是手头给我的的证件是pdf，不多几十张，由于需要一页显示，所以需要把他们转成图片。
百度在线pdf转jpg，好家伙，一大堆积网页，随便点一个开搞，一张，有点慢,算了等等，转换完成点下载，WHT？ 12kb，好几分钟后，下载完成,然后上传第二个，你妹，需要会员，好吧注册个，终于转换了第二个，准备第三个，你妹，又不够了，要订阅，有着个订阅的钱，我还不如开个wps会员呢，连续试了几个网页，全是一个尿性，下载慢，数量少，不能批量，于是突然想到以前用aspose.word把word 转pdf，于是赶紧试了下，可以实现。
Document pdfDocument = new Document(@"D:\pdfdir\jhrs.com.pdf");
for (int pageCount = 1; pageCount <= pdfDocument.Pages.Count; pageCount++)
{
using (FileStream imageStream = new FileStream($"jhrs.com_{i}.png", FileMode.Create))
{
Resolution resolution = new Resolution(300);
PngDevice pngDevice = new PngDevice(resolution);
pngDevice.Process(pdfDocument.Pages[pageCount], imageStream);
imageStream.Close();
}
}
Aspose.pdf无水印版下载
Aspose.pdf添加文字水印
/// <summary>
/// pdf添加文字水印(自定义水印行数和列数)
/// </summary>
/// <param name="pdfStream">pdf文件流</param>
/// <param name="watermarkText">水印文字</param>
/// <param name="fontSize">文字大小</param>
/// <param name="fontColor">文字颜色</param>
/// <param name="typeface">字体：（中文水印请自行查找相应字体的英文名称，如：宋体（SimSun），黑体（SimHei），仿宋（FangSong），微软雅黑（Microsoft YaHei）等等...）</param>
/// <param name="rotation">倾斜角度</param>
/// <param name="opacity">不透明度（值为：0-1）</param>
/// <param name="watermarkRowNum">水印行数</param>
/// <param name="watermarkColumnNum">水印列数</param>
/// <returns></returns>
public Stream AddTextWatermarkCustom(Stream pdfStream, string watermarkText, float fontSize, Aspose.Pdf.Color fontColor, string typeface, double rotation = 0, double opacity = 0, int watermarkRowNum = 1, int watermarkColumnNum = 1)
{
try
{
/*计算倾斜高度-start*/
var angle = Math.Abs(rotation);
var width = watermarkText.Length * fontSize;
var radian = 2 * Math.PI / 360 * angle;
var top = Math.Sin(radian) * width;
/*计算倾斜高度-end*/
Document document = new Document(pdfStream);
for (int i = 1; i <= document.Pages.Count; i++)
{
var pageWidth = document.Pages[i].GetPageRect(false).Width;
var pageHeight = document.Pages[i].GetPageRect(false).Height;
WatermarkArtifact artifact = new WatermarkArtifact();
artifact.SetTextAndState(watermarkText, new TextState
{
FontSize = fontSize,
ForegroundColor = fontColor,
Font = FontRepository.FindFont(typeface),
});
artifact.Rotation = rotation;
artifact.Opacity = opacity;
artifact.IsBackground = false;
if (watermarkRowNum == 1 && watermarkColumnNum == 1)
{
artifact.ArtifactHorizontalAlignment = HorizontalAlignment.Center;
artifact.ArtifactVerticalAlignment = VerticalAlignment.Center;
document.Pages[i].Artifacts.Add(artifact);
}
else
{
artifact.ArtifactHorizontalAlignment = HorizontalAlignment.Left;
artifact.ArtifactVerticalAlignment = VerticalAlignment.Top;
for (int j = 1; j <= watermarkColumnNum; j++)
{
artifact.LeftMargin = (j - 1) * (pageWidth / watermarkColumnNum) + fontSize;
for (int z = 1; z <= watermarkRowNum; z++)
{
artifact.TopMargin = (z - 1) * (pageHeight / watermarkRowNum) + top;
document.Pages[i].Artifacts.Add(artifact);
}
}
}
}
Stream outStream = new MemoryStream();
document.Save(outStream, SaveFormat.Pdf);
outStream.Seek(0, SeekOrigin.Begin);
return outStream;
}
catch (Exception ex)
{
throw ex;
}
}
/// <summary>
/// pdf添加文字水印(平铺)
/// </summary>
/// <param name="pdfStream">pdf文件流</param>
/// <param name="watermarkText">水印文字</param>
/// <param name="fontSize">文字大小</param>
/// <param name="fontColor">文字颜色</param>
/// <param name="typeface">字体：（中文水印请自行查找相应字体的英文名称，如：宋体（SimSun），黑体（SimHei），仿宋（FangSong），微软雅黑（Microsoft YaHei）等等...）</param>
/// <param name="rotation">倾斜角度</param>
/// <param name="opacity">不透明度（值为：0-1）</param>
/// <param name="density">水印密度（值为0-1）</param>
/// <returns></returns>
public Stream AddTextWatermarkTile(Stream pdfStream, string watermarkText, float fontSize, Aspose.Pdf.Color fontColor, string typeface, double rotation = 0, double opacity = 0, double density = 1)
{
try
{
Document document = new Document(pdfStream);
/*计算水印详细-start*/
var angle = Math.Abs(rotation);
var width = watermarkText.Length * fontSize;
var radian = 2 * Math.PI / 360 * angle;
var top = Math.Sin(radian) * width;
var row = Math.Cos(radian) * width;
var pageWidth = document.Pages[1].GetPageRect(false).Width;
var pageHeight = document.Pages[1].GetPageRect(false).Height;
int watermarkRowNum = (int)(pageHeight / top * density);
int watermarkColumnNum = (int)(pageHeight / row * density);
if (rotation == 0)
{
watermarkRowNum = (int)(pageHeight / fontSize * density);
watermarkColumnNum = (int)(pageHeight / width * density);
}
/*计算水印详细-end*/
for (int i = 1; i <= document.Pages.Count; i++)
{
WatermarkArtifact artifact = new WatermarkArtifact();
artifact.SetTextAndState(watermarkText, new TextState
{
FontSize = fontSize,
ForegroundColor = fontColor,
Font = FontRepository.FindFont(typeface),
});
artifact.Rotation = rotation;
artifact.Opacity = opacity;
artifact.IsBackground = false;
artifact.ArtifactHorizontalAlignment = HorizontalAlignment.Left;
artifact.ArtifactVerticalAlignment = VerticalAlignment.Top;
for (int j = 1; j <= watermarkColumnNum; j++)
{
artifact.LeftMargin = (j - 1) * (pageWidth / watermarkColumnNum) + fontSize;
for (int z = 1; z <= watermarkRowNum; z++)
{
artifact.TopMargin = (z - 1) * (pageHeight / watermarkRowNum) + top;
document.Pages[i].Artifacts.Add(artifact);
}
}
}
Stream outStream = new MemoryStream();
document.Save(outStream, SaveFormat.Pdf);
outStream.Seek(0, SeekOrigin.Begin);
return outStream;
}
catch (Exception ex)
{
throw ex;
}
}
Aspose.pdf无水印版下载
调用代码部分代码：
Stream stream = File.OpenRead(@"C:\Users\HEDY\Desktop\Test\2.pdf");
var outStream = AddTextWatermarkCustom(stream, "测试水印文字", 32, Color.Blue, "SimSun", 45, 0.5, 6, 3);
var saveStream = new FileStream($@"C:\Users\HEDY\Desktop\Test\1_{Guid.NewGuid()}.pdf", FileMode.Create);
outStream.CopyTo(saveStream);
outStream.Close();
saveStream.Close();
Aspose.pdf添加图片水印
/// <summary>
/// pdf添加图片水印(自定义水印行数和列数)
/// </summary>
/// <param name="pdfStream">pdf文件流</param>
/// <param name="imgurl">水印文字</param>
/// <param name="rotation">倾斜角度</param>
/// <param name="opacity">不透明度（值为：0-1）</param>
/// <param name="watermarkRowNum">水印行数</param>
/// <param name="watermarkColumnNum">水印列数</param>
/// <returns></returns>
public Stream AddImgWatermarkCustom(Stream pdfStream, string imgPath, double rotation = 0, double opacity = 0, int watermarkRowNum = 1, int watermarkColumnNum = 1)
{
try
{
/*计算倾斜高度-start*/
var angle = Math.Abs(rotation);
var pic = new Bitmap(imgPath);
var width = pic.Width;
var radian = 2 * Math.PI / 360 * angle;
var top = Math.Sin(radian) * width;
/*计算倾斜高度-end*/
Document document = new Document(pdfStream);
for (int i = 1; i <= document.Pages.Count; i++)
{
var pageWidth = document.Pages[i].GetPageRect(false).Width;
var pageHeight = document.Pages[i].GetPageRect(false).Height;
WatermarkArtifact artifact = new WatermarkArtifact();
artifact.SetImage(File.OpenRead(imgPath));
artifact.Rotation = rotation;
artifact.Opacity = opacity;
artifact.IsBackground = false;
if (watermarkRowNum == 1 && watermarkColumnNum == 1)
{
artifact.ArtifactHorizontalAlignment = HorizontalAlignment.Center;
artifact.ArtifactVerticalAlignment = VerticalAlignment.Center;
document.Pages[i].Artifacts.Add(artifact);
}
else
{
artifact.ArtifactHorizontalAlignment = HorizontalAlignment.Left;
artifact.ArtifactVerticalAlignment = VerticalAlignment.Top;
for (int j = 1; j <= watermarkColumnNum; j++)
{
artifact.LeftMargin = (j - 1) * (pageWidth / watermarkColumnNum) + pic.Height;
for (int z = 1; z <= watermarkRowNum; z++)
{
artifact.TopMargin = (z - 1) * (pageHeight / watermarkRowNum) + top;
document.Pages[i].Artifacts.Add(artifact);
}
}
}
}
Stream outStream = new MemoryStream();
document.Save(outStream, SaveFormat.Pdf);
outStream.Seek(0, SeekOrigin.Begin);
return outStream;
}
catch (Exception ex)
{
throw ex;
}
}
/// <summary>
/// pdf添加图片水印(平铺)
/// </summary>
/// <param name="pdfStream">pdf文件流</param>
/// <param name="watermarkText">水印文字</param>
/// <param name="rotation">倾斜角度</param>
/// <param name="opacity">不透明度（值为：0-1）</param>
/// <param name="density">水印密度（值为0-1）</param>
/// <returns></returns>
public Stream AddImgWatermarkTile(Stream pdfStream, string imgPath, double rotation = 0, double opacity = 0, double density = 1)
{
try
{
Document document = new Document(pdfStream);
/*计算水印详细-start*/
var angle = Math.Abs(rotation);
var pic = new Bitmap(imgPath);
var width = pic.Width;
var imgHeight = pic.Height;
var radian = 2 * Math.PI / 360 * angle;
var top = Math.Sin(radian) * width;
var row = Math.Cos(radian) * width;
var pageWidth = document.Pages[1].GetPageRect(false).Width;
var pageHeight = document.Pages[1].GetPageRect(false).Height;
int watermarkRowNum = (int)(pageHeight / top * density);
int watermarkColumnNum = (int)(pageHeight / row * density);
if (rotation == 0)
{
watermarkRowNum = (int)(pageHeight / imgHeight * density);
watermarkColumnNum = (int)(pageHeight / width * density);
}
/*计算水印详细-end*/
for (int i = 1; i <= document.Pages.Count; i++)
{
WatermarkArtifact artifact = new WatermarkArtifact();
artifact.SetImage(File.OpenRead(imgPath));
artifact.Rotation = rotation;
artifact.Opacity = opacity;
artifact.IsBackground = false;
artifact.ArtifactHorizontalAlignment = HorizontalAlignment.Left;
artifact.ArtifactVerticalAlignment = VerticalAlignment.Top;
for (int j = 1; j <= watermarkColumnNum; j++)
{
artifact.LeftMargin = (j - 1) * (pageWidth / watermarkColumnNum) + imgHeight;
for (int z = 1; z <= watermarkRowNum; z++)
{
artifact.TopMargin = (z - 1) * (pageHeight / watermarkRowNum) + top;
document.Pages[i].Artifacts.Add(artifact);
}
}
}
Stream outStream = new MemoryStream();
document.Save(outStream, SaveFormat.Pdf);
outStream.Seek(0, SeekOrigin.Begin);
return outStream;
}
catch (Exception ex)
{
throw ex;
}
}
Aspose.pdf无水印版下载
调用代码部分代码：
Stream stream = File.OpenRead(@"C:\Users\HEDY\Desktop\Test\2.pdf");
var outStream = AddImgWatermarkTile(stream, @"C:\Users\HEDY\Desktop\Test\123.jpg", 0, 0.5,0.5);
var saveStream = new FileStream($@"C:\Users\HEDY\Desktop\Test\1_{Guid.NewGuid().ToString("N")}.pdf", FileMode.Create);
outStream.CopyTo(saveStream);
outStream.Close();
saveStream.Close();
Aspose.pdf无水印版下载
代码引用来源：https://www.cnblogs.com/Shi-zy/p/15494760.html，未经测试代码，留作备用而已。