c# 系列pdf转图片 各种处理2--net3.1到net8

net3.1 pdf转图片目前只有两种

Acrobat.dll

要准备的：下载Adobe Acrobat Professional 9

添加引用:Microsoft.CSharp.dll，Acrobat.dll 和Microsoft.VisualBasic.dll

/// <summary>
/// 将PDF文档转换为图片的方法，你可以像这样调用该方法：ConvertPDF2Image("F:\\A.pdf", "F:\\", "A", 0, 0, null, 0);
/// 因为大多数的参数都有默认值，startPageNum默认值为1，endPageNum默认值为总页数，
/// imageFormat默认值为ImageFormat.Jpeg，resolution默认值为1
/// </summary>
/// <param name="pdfInputPath">PDF文件路径</param>
/// <param name="imageOutputPath">图片输出路径</param>
/// <param name="imageName">图片的名字，不需要带扩展名</param>
/// <param name="startPageNum">从PDF文档的第几页开始转换，默认值为1</param>
/// <param name="endPageNum">从PDF文档的第几页开始停止转换，默认值为PDF总页数</param>
/// <param name="imageFormat">设置所需图片格式</param>
/// <param name="resolution">设置图片的分辨率，数字越大越清晰，默认值为1</param>
public static void ConvertPDF2Image(string pdfInputPath, string imageOutputPath,
string imageName, int startPageNum, int endPageNum, ImageFormat imageFormat, double resolution)
{
    Acrobat.CAcroPDDoc pdfDoc = null;
    Acrobat.CAcroPDPage pdfPage = null;
    Acrobat.CAcroRect pdfRect = null;
    Acrobat.CAcroPoint pdfPoint = null;
 
    // Create the document (Can only create the AcroExch.PDDoc object using late-binding)
    // Note using VisualBasic helper functions, have to add reference to DLL
    pdfDoc = (Acrobat.CAcroPDDoc)Microsoft.VisualBasic.Interaction.CreateObject("AcroExch.PDDoc", "");
 
    // validate parameter
    if (!pdfDoc.Open(pdfInputPath)) { throw new FileNotFoundException(); }
    if (!Directory.Exists(imageOutputPath)) { Directory.CreateDirectory(imageOutputPath); }
    if (startPageNum <= 0) { startPageNum = 1; }     if (endPageNum > pdfDoc.GetNumPages() || endPageNum <= 0) { endPageNum = pdfDoc.GetNumPages(); }     if (startPageNum > endPageNum) { int tempPageNum = startPageNum; startPageNum = endPageNum; endPageNum = startPageNum; }
    if (imageFormat == null) { imageFormat = ImageFormat.Jpeg; }
    if (resolution <= 0) { resolution = 1; }
 
    // start to convert each page
    for (int i = startPageNum; i <= endPageNum; i++)
    {
        pdfPage = (Acrobat.CAcroPDPage)pdfDoc.AcquirePage(i - 1);
        pdfPoint = (Acrobat.CAcroPoint)pdfPage.GetSize();
        pdfRect = (Acrobat.CAcroRect)Microsoft.VisualBasic.Interaction.CreateObject("AcroExch.Rect", "");
 
        int imgWidth = (int)((double)pdfPoint.x * resolution);
        int imgHeight = (int)((double)pdfPoint.y * resolution);
 
        pdfRect.Left = 0;
        pdfRect.right = (short)imgWidth;
        pdfRect.Top = 0;
        pdfRect.bottom = (short)imgHeight;
 
        // Render to clipboard, scaled by 100 percent (ie. original size)
        // Even though we want a smaller image, better for us to scale in .NET
        // than Acrobat as it would greek out small text
        pdfPage.CopyToClipboard(pdfRect, 0, 0, (short)(100 * resolution));
 
        IDataObject clipboardData = Clipboard.GetDataObject();
 
        if (clipboardData.GetDataPresent(DataFormats.Bitmap))
        {
            Bitmap pdfBitmap = (Bitmap)clipboardData.GetData(DataFormats.Bitmap);
            pdfBitmap.Save(Path.Combine(imageOutputPath, imageName) + ".jpg", imageFormat);
            pdfBitmap.Dispose();
        }
    }
 
    pdfDoc.Close();
    Marshal.ReleaseComObject(pdfPage);
    Marshal.ReleaseComObject(pdfRect);
    Marshal.ReleaseComObject(pdfDoc);
    Marshal.ReleaseComObject(pdfPoint);
}

注意：转换速度、图片质量都还不错，但是无法跨平台使用。

Ghostscript.dll 功能很强大，也能跨平台，但是必须安装 gs10031w64.exe,请加大酌情使用

https://download.youkuaiyun.com/download/zuoming120/90575414?spm=1001.2014.3001.5501 这个是资源包

net8 有两种产品

1  Docnet.Core

https://download.youkuaiyun.com/download/zuoming120/90575430 这个是我的测试demo

有些时候图片清晰度不够。但是可用

2 itext7.pdfimage

下载 https://github.com/thombrink/itext7.pdfimage

新建core8项目，安装itext7和system.drawing.common

修改 imageListener下有不安全的代码

  unsafe
  {
      for (int y = 0; y < image.Height; y++)
      {
          byte* ptrMask = (byte*)bitsMask.Scan0 + y * bitsMask.Stride;
          byte* ptrInput = (byte*)bitsInput.Scan0 + y * bitsInput.Stride;
          byte* ptrOutput = (byte*)bitsOutput.Scan0 + y * bitsOutput.Stride;
          for (int x = 0; x < image.Width; x++)
          {
              ptrOutput[4 * x] = ptrInput[4 * x];           // blue
              ptrOutput[4 * x + 1] = ptrInput[4 * x + 1];   // green
              ptrOutput[4 * x + 2] = ptrInput[4 * x + 2];   // red
              ptrOutput[4 * x + 3] = ptrMask[4 * x];        // alpha
          }
      }
  }

改成 

// 遍历每一行  
for (int y = 0; y < image.Height; y++)  
{  
    // 计算每行的起始字节位置  
    int scanOffsetInput = y * bitsInput.Stride;  
    int scanOffsetMask = y * bitsMask.Stride;  
    int scanOffsetOutput = y * bitsOutput.Stride;  

    // 获取当前行的字节数组  
    byte[] scanlineInput = new byte[bitsInput.Stride];  
    byte[] scanlineMask = new byte[bitsMask.Stride];
    byte[] scanlineOutput = new byte[bitsOutput.Stride];
    Marshal.Copy(bitsInput.Scan0 + scanOffsetInput, scanlineInput, 0, scanlineInput.Length);  
    Marshal.Copy(bitsMask.Scan0 + scanOffsetMask, scanlineMask, 0, scanlineMask.Length);  

    // 遍历每一列（或每一像素）  
    for (int x = 0; x < image.Width; x++)  
    {  
        // 计算当前像素在字节数组中的位置（基于每个像素4个字节）  
        int pixelOffsetInput = x * 4;  
        int pixelOffsetMask = x * 4;  
        int pixelOffsetOutput = x * 4;  

        // 读取输入图像的RGB值  
        byte blue = scanlineInput[pixelOffsetInput];  
        byte green = scanlineInput[pixelOffsetInput + 1];  
        byte red = scanlineInput[pixelOffsetInput + 2];  

        // 读取遮罩图像的alpha值  
        byte alpha = scanlineMask[pixelOffsetMask];  

        // 将值写入输出图像的对应位置  
        scanlineOutput[pixelOffsetOutput] = blue;  
        scanlineOutput[pixelOffsetOutput + 1] = green;  
        scanlineOutput[pixelOffsetOutput + 2] = red;  
        scanlineOutput[pixelOffsetOutput + 3] = alpha;  
    }  

    // 将处理过的行复制回输出图像的BitmapData中  
    Marshal.Copy(scanlineOutput, 0, bitsOutput.Scan0 + scanOffsetOutput, scanlineOutput.Length);  
}  

然后运行两个demo，就可以了，切记必须是net8项目