using Microsoft.Office.Core;
using System;
using System.IO;
using System.Windows.Forms;
using Excel = Microsoft.Office.Interop.Excel;
using PowerPoint = Microsoft.Office.Interop.PowerPoint;
using Word = Microsoft.Office.Interop.Word;

namespace WindowsFormsApp4
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            bool isSuccess = DOCConvertToPDF(Directory.GetCurrentDirectory() + "\\aa.docx", Directory.GetCurrentDirectory() + "\\aa.pdf");
            if (isSuccess)
            {
                pdfViewer1.LoadFromFile(Directory.GetCurrentDirectory() + "\\aa.pdf");
            }
        }

        /// <summary>
        /// Word轉換成pdf
        /// </summary>
        /// <param name="sourcePath">源文件路徑</param>
        /// <param name="targetPath">目標文件路徑</param>
        /// <returns>true=轉換成功</returns>
        public static bool DOCConvertToPDF(string sourcePath, string targetPath)
        {
            bool result = false;
            Word.Application app = new Word.Application();
            Word.Document doc = null;
            object missing = System.Reflection.Missing.Value;
            object saveChanges = Word.WdSaveOptions.wdDoNotSaveChanges;
            try
            {
                app.Visible = false;
                doc = app.Documents.Open(sourcePath);
                doc.ExportAsFixedFormat(targetPath, Word.WdExportFormat.wdExportFormatPDF);
                result = true;
            }
            catch (Exception ex)
            {
                result = false;
                throw new ApplicationException(ex.Message);
            }
            finally
            {
                if (doc != null)
                {
                    doc.Close(ref saveChanges, ref missing, ref missing);
                    doc = null;
                }
                if (app != null)
                {
                    app.Quit(ref missing, ref missing, ref missing);
                    app = null;
                }
                GC.Collect();
                GC.WaitForPendingFinalizers();
            }
            return result;
        }

    }
}

/// <summary>
/// 把Excel文件轉換成PDF格式文件
/// </summary>
/// <param name="sourcePath">源文件路徑</param>
/// <param name="targetPath">目標文件路徑</param>
/// <returns>true=轉換成功</returns>
public static bool XLSConvertToPDF(string sourcePath, string targetPath)
{
    bool result = false;
    Excel.XlFixedFormatType targetType = Excel.XlFixedFormatType.xlTypePDF;
    object missing = Type.Missing;
    Excel.Application app = null;
    Excel.Workbook book = null;
    try
    {
        app = new Excel.Application();
        object target = targetPath;
        object type = targetType;
        book = app.Workbooks.Open(sourcePath, missing, missing, missing, missing, missing,
        missing, missing, missing, missing, missing, missing, missing, missing, missing);
        book.ExportAsFixedFormat(targetType, target, Excel.XlFixedFormatQuality.xlQualityStandard, true, false, missing, missing, missing, missing);
        result = true;
    }
    catch (Exception ex)
    {
        result = false;
        throw new ApplicationException(ex.Message);
    }
    finally
    {
        if (book != null)
        {
            book.Close(true, missing, missing);
            book = null;
        }
        if (app != null)
        {
            app.Quit();
            app = null;
        }
        GC.Collect();
        GC.WaitForPendingFinalizers();
    }
    return result;
}

///<summary>
/// 把PowerPoint文件轉換成PDF格式文件
///</summary>
///<param name="sourcePath">源文件路徑</param>
///<param name="targetPath">目標文件路徑</param>
///<returns>true=轉換成功</returns>
public static bool PPTConvertToPDF(string sourcePath, string targetPath)
{
    bool result = false;

    PowerPoint.PpSaveAsFileType targetFileType = PowerPoint.PpSaveAsFileType.ppSaveAsPDF;
    object missing = Type.Missing;
    PowerPoint.Application app = null;
    PowerPoint.Presentation pres = null;
    try
    {
        app = new PowerPoint.Application();
        pres = app.Presentations.Open(sourcePath, MsoTriState.msoTrue, MsoTriState.msoFalse, MsoTriState.msoFalse);
        pres.SaveAs(targetPath, targetFileType, Microsoft.Office.Core.MsoTriState.msoTrue);
        result = true;
    }
    catch (Exception ex)
    {
        result = false;
        throw new ApplicationException(ex.Message);
    }
    finally
    {
        if (pres != null)
        {
            pres.Close();
            pres = null;
        }
        if (app != null)
        {
            app.Quit();
            app = null;
        }
        GC.Collect();
        GC.WaitForPendingFinalizers();
    }
    return result;
}