C# Winform 使用Adobe Acrobat 实现 PDF 转 图片

/// <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);
}