C#.Net PDF convert to Image

先下載Adobe Reader X Pro以上的版本，語言包下載點
安裝完成後去資料夾底下搜尋『Acrobat.dll』，開啟Visual Studio專案，並將『Acrobat.dll』加入參考

接著加入『Microsoft.VisualBasic』

將以下程式碼貼上去就可以使用了，註解都幫各位寫好了，想知道原理看參考文獻或是註解文字即可

使用程式下載或是Github必須要有『Acrobat.dll』，否則會出現找不到dll錯誤

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Drawing.Imaging;
using System.Linq;
using System.Runtime.InteropServices;
using System.Text;
using System.Windows.Forms;

namespace PDFConvertImage
{
    public partial class PDFtoImage : Form
    {
        public PDFtoImage()
        {
            InitializeComponent();
        }

        private void button_LoadFile_Click(object sender, EventArgs e)
        {
            OpenFileDialog dialog = new OpenFileDialog();
            dialog.InitialDirectory = getDeskPath();
            dialog.Filter = "PDF|*.pdf";
            dialog.RestoreDirectory = true;

            if (dialog.ShowDialog() == DialogResult.OK)
            {
                //倍數
                short pixelZoom = 10;

                //http://www.cnblogs.com/kongxianghai/archive/2012/04/09/2438321.html
                //頁
                Acrobat.CAcroPDPage pdfPage = null;

                //頁面大小
                Acrobat.CAcroPoint pdfPoint = null;

                //矩形
                Acrobat.CAcroRect pdfRect = null;

                //http://forums.codeguru.com/showthread.php?31751-What-do-I-need-for-CreateObject(-AcroExch.PDDoc-)
                Acrobat.CAcroPDDoc pdfDoc = (Acrobat.CAcroPDDoc)Microsoft.VisualBasic.Interaction.CreateObject("AcroExch.PDDoc", "");
                if (pdfDoc.Open(dialog.FileName))
                {
                    //PDF頁數
                    int pageCount = pdfDoc.GetNumPages();
                    for (int i = 0; i < pageCount; i++)
                    {
                        //取得目前頁數
                        pdfPage = (Acrobat.CAcroPDPage)pdfDoc.AcquirePage(i);

                        //取得頁面大小
                        pdfPoint = (Acrobat.CAcroPoint)pdfPage.GetSize();

                        //http://forums.adobe.com/thread/305835
                        pdfRect = (Acrobat.CAcroRect)Microsoft.VisualBasic.Interaction.CreateObject("AcroExch.Rect", "");

                        //左邊
                        pdfRect.Left = 0;

                        //頂端
                        pdfRect.Top = 0;

                        //右邊
                        pdfRect.right = (short)(pdfPoint.x * pixelZoom);

                        //底部
                        pdfRect.bottom = (short)(pdfPoint.y * pixelZoom);

                        //取得整個頁面
                        pdfPage.CopyToClipboard(pdfRect, (short)(pdfRect.Left * pixelZoom), (short)(pdfRect.Top * pixelZoom), (short)(100 * pixelZoom));

                        ///<summary>http://msdn.microsoft.com/en-us/library/system.windows.forms.idataobject.aspx
                        ///You retrieve stored data from an IDataObject by calling the GetData method and specifying the data format in the format parameter. Set the  autoConvert parameter to false to retrieve only data that was stored in the specified format. To convert the stored data to the specified format, set autoConvert to true, or do not use autoConvert.
                        ///</summary>
                        IDataObject loClipboardData = Clipboard.GetDataObject();

                        //Get Image
                        Bitmap pdfBitmap = (Bitmap)loClipboardData.GetData(DataFormats.Bitmap);

                        //Save Image
                        pdfBitmap.Save(getDeskPath() + (i + 1) + ".jpeg", ImageFormat.Jpeg);
                    }
                    pdfDoc.Close();

                    ///<summary>http://msdn.microsoft.com/en-us/library/system.runtime.interopservices.marshal.releasecomobject.aspx
                    ///This method is used to explicitly control the lifetime of a COM object used from managed code. You should use this method to free the underlying COM object that holds references to resources in a timely manner or when objects must be freed in a specific order.
                    ///</summary>
                    Marshal.ReleaseComObject(pdfPage);
                    Marshal.ReleaseComObject(pdfRect);
                    Marshal.ReleaseComObject(pdfDoc);
                    MessageBox.Show("轉換成功");
                }
                else
                {
                    MessageBox.Show("檔案可能損毀了");
                }
            }
        }

        //取得桌面路徑
        private static string getDeskPath()
        {
            return System.Environment.GetFolderPath(Environment.SpecialFolder.DesktopDirectory) + @"\";
        }

        private void PDFtoImage_Load(object sender, EventArgs e)
        {
            this.MaximizeBox = false;
            this.MinimizeBox = false;
        }
    }
}

參考資料：
http://blog.3snews.net/space.php?uid=10159&do=blog&id=61043
http://forums.codeguru.com/showthread.php?31751-What-do-I-need-for-CreateObject(-AcroExch.PDDoc-)
http://bbs.csdn.net/topics/360038342
http://forums.adobe.com/thread/305835
http://mypaper.pchome.com.tw/middlehuang/post/1321751402
http://msdn.microsoft.com/en-us/library/system.windows.forms.idataobject.aspx
http://www.cnblogs.com/kongxianghai/archive/2012/04/09/2438321.html