C#编写的类库，实现将pdf转换成图片（jpg)

最近在网上查了很多资料，刚开始的做的不是太好，感觉实现起来很困难。

那个pdf转换成图片用C++相对来说很麻烦，因为它要调用一起其他的库文件，使用起来不太好办，最近有点忙也没整理这个。但C#和Java的现成的程序都有，用C++的有，是调用Acrobat中的文件自己编写的，但不是生成图片，只是用VC显示，网址是：
http://www.evget.com/zh-CN/Info/catalog/6594.html
有个用C#实现的网址是：
http://www.codeproject.com/KB/cs/GhostScriptUseWithCSharp.aspx
这里面有具体的步骤及如何调用别人的库，但C++使用起来不太好办。
这里有一个pdflib的操作，可以操作页，也是C#的：
http://www.codeproject.com/KB/graphics/AnotherPDFLib.aspx
下面还有用C++如何调用C#的：
http://blog.csdn.net/suoxd123/archive/2010/01/08/5157668.aspx

其实我建议直接显示PDf页，并在上面直接操作，不用再转成图片，如果转成图片也很麻烦。但用C++语言做起来不太好做。

 

后来在做了一些研究后，发现利用C#做很容易，利用的是其他人的程序，http://www.codeproject.com/KB/GDI-plus/pdfthumbnail.aspx，在这样上面可以利用Acrobat将pdf转换成图片。

我将程序进行了修改，如下：

 

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;
using System.Drawing;
using System.Windows.Forms;
using System.Runtime.InteropServices;
using Acrobat;

namespace PDFLibSharp
{
    public class PDFLibSharp
    {
        private string filename;
        int page;

        /// <summary>
        /// the construct function to create the filename and page
        /// </summary>
        /// <param name="filenamesource"></param>
        /// <param name="pagesource"></param>
       
        public int ConvertPtoI(string filenamesource, int pagesource)
        {
            filename = filenamesource;
            page = pagesource;
            //assert the file is pdf or not
            if(!(filename.EndsWith(".pdf") || filename.EndsWith(".PDF")))
            {
                return 0;  //0 represent there is no file
            }               

            //begin to change
            try
            {
                Acrobat.CAcroPDDoc pdfDoc;
                pdfDoc = (Acrobat.CAcroPDDoc)Microsoft.VisualBasic.Interaction.CreateObject("AcroExch.PDDoc", "");
                bool ret = pdfDoc.Open(filename);
                if(!ret)
                {
                    return 1;  //1 can not open to read
                }

                //the page is too big
                int pageCount = pdfDoc.GetNumPages();
                if(page >= pageCount || page <= 0)
                {
                    return 2;
                }

                //get the page and the size
                Acrobat.CAcroPDPage pdfPage;
                pdfPage = (Acrobat.CAcroPDPage)pdfDoc.AcquirePage(page);
                Acrobat.CAcroPoint pdfPoint = (Acrobat.CAcroPoint)pdfPage.GetSize();
                Acrobat.CAcroRect pdfRect = (Acrobat.CAcroRect)Microsoft.VisualBasic.Interaction.CreateObject("AcroExch.Rect", "");

                pdfRect.Left = 0;
                pdfRect.right = pdfPoint.x;
                pdfRect.Top = 0;
                pdfRect.bottom = pdfPoint.y;

                //copy it to the clipboard
                pdfPage.CopyToClipboard(pdfRect, 0, 0, 100);
                IDataObject clipboardData = Clipboard.GetDataObject();

                if (clipboardData.GetDataPresent(DataFormats.Bitmap))
                {
                    Bitmap pdfBitmap = (Bitmap)clipboardData.GetData(DataFormats.Bitmap);

                    // Size of generated thumbnail in pixels
                    int thumbnailWidth = 1000;
                    int thumbnailHeight = 1000;
                 
                    // Render to small image using the bitmap class
                    Image pdfImage = pdfBitmap.GetThumbnailImage(thumbnailWidth, thumbnailHeight,
                                                                 null, IntPtr.Zero);

                    // Create new blank bitmap (+ 7 for template border)      
                    Bitmap thumbnailBitmap = new Bitmap(thumbnailWidth + 7, thumbnailHeight + 7,
                                                        System.Drawing.Imaging.PixelFormat.Format32bppArgb);

                    // To overlayout the template with the image, we need to set the transparency
                    // http://www.sellsbrothers.com/writing/default.aspx?content=dotnetimagerecoloring.htm
                    //     templateBitmap.MakeTransparent();

                    using (Graphics thumbnailGraphics = Graphics.FromImage(thumbnailBitmap))
                    {
                        // Draw rendered pdf image to new blank bitmap
                        thumbnailGraphics.DrawImage(pdfImage, 2, 2, thumbnailWidth, thumbnailHeight);

                        // Draw template outline over the bitmap (pdf with show through the transparent area)
                        //      thumbnailGraphics.DrawImage(templateBitmap, 0, 0);
                        // Save as .png file
                        string outputFile = filename.Substring(0, filename.Length - 4) + '_' + page.ToString() + ".png";
                        thumbnailBitmap.Save(outputFile, System.Drawing.Imaging.ImageFormat.Png);
                        Console.WriteLine("Generated thumbnail... {0}", outputFile);
                    }
                    pdfDoc.Close();
                    // Not sure how why it is to do this, but Acrobat is not the best behaved COM object
                    // see http://blogs.msdn.com/yvesdolc/archive/2004/04/17/115379.aspx
                    Marshal.ReleaseComObject(pdfPage);
                    Marshal.ReleaseComObject(pdfRect);
                    Marshal.ReleaseComObject(pdfDoc);
                }

            }
            catch (System.Exception ex)
            {
                return 10;
            }
            return 5;
           
        }

        //////////////////////////////////////////////////////////////////////////
        //////////////////////////////////////////////////////////////////////////
    }
}

 

后面的一篇文章是利用C++调用这个类库，可以参考下一篇文章。