Introduction to Office Solutions Using Visual Studio Tools for Office

This chapter is from the book

Visual Studio Tools for Office: Using C# with Excel, Word, Outlook, and InfoPath

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This chapter is from the book

This chapter is from the book 

Visual Studio Tools for Office: Using C# with Excel, Word, Outlook, and InfoPath

Learn More Buy

Office Automation Executables

We now consider each of these three patterns of Office solutions in more detail. Office solutions that use the automation executable pattern start up an Office application in a very straightforward manner—by creating a new instance of the Application object associated with the Office application. Because the automation executable controls the Office application, the automation executable runs code at startup and any time thereafter when executing control returns to the automation executable.

When an automation executable uses new to create an Application object, the automation executable controls the lifetime of the application by holding the created Application object in a variable. Office determines whether it can shut down by determining the reference count or number of clients that are using its Application object.

In Listing 2-1, as soon as new is used to create the myExcelApp variable, Excel starts and adds one to its count of clients that it knows are holding a reference to Excel's Application object. When the myExcelApp variable goes out of scope (when Main exits) .NET garbage collection releases the object and Excel is notified that the console application no longer needs Excel's Application object. This causes Excel's count of clients holding a reference to Excel's Application object to go to zero and Excel exits as no clients are using Excel anymore.

When you create an Office application by creating a new instance of the Application object, the application starts up without showing its window. This is useful because you can automate the application without distracting the user by popping up windows. If you need to show the application window, you can set the Visible property of the Application object to true. If you make the main window visible, the user controls the lifetime of the application. In Excel, the application will not exit until the user quits the application and your variable holding the Excel Application object is garbage collected. Word behaves differently—the application exits when the user quits the application even if a variable is still holding an instance of the Word Application object.

Listing 2-1 sets the status bar of Excel to say "Hello World" and opens a new blank workbook in Excel by calling the Add method of Excel's Workbooks collection. Chapters 3 through 5 cover the Excel object model in more detail.

Listing 2-1: Automation of a Excel via a console application.

using System;
using Excel = Microsoft.Office.Interop.Excel;
using System.Windows.Forms;

namespace ConsoleApplication
{
 class Program
 {
  static bool exit = false;
  
  static void Main(string[] args)
  {
   Excel.Application myExcelApp = new Excel.Application();
   myExcelApp.Visible = true;
   myExcelApp.StatusBar = "Hello World";
   myExcelApp.Workbooks.Add(System.Type.Missing);

   myExcelApp.SheetBeforeDoubleClick += new Excel.AppEvents_SheetBeforeDoubleClickEventHandler(myExcelApp_SheetBeforeDoubleClick);

   while (exit == false)
    System.Windows.Forms.Application.DoEvents();
  }

  static void myExcelApp_SheetBeforeDoubleClick(object Sh, Microsoft.Office.Interop.Excel.Range Target, ref bool Cancel)
  {
   exit = true;
  }
 }
}

Listing 2-1 also illustrates how an automation executable can yield time back to the Office application. A reference to the System.Windows.Forms assembly must be added to the project. After a event handlers are hooked up, System.Windows.Forms.Application.DoEvents() is called in a loop to allow the Excel application to run normally. If the user double clicks on a cell, Office yields time back to the event handler in the automation executable. In the handler for the double click event, we set the static variable exit to true which will cause the loop calling DoEvents to exit and the automation executable to exit.

You can see the lifetime management of Excel in action by running the automation executable in Listing 2-1 and exiting Excel without double clicking on a cell. Excel will continue to run in a hidden state, waiting for the console application to release its reference to Excel's Application object.

Creating a Console Application that Automates Word

In this section, we are going to walk through the creation of a simple console application that automates Word. A wiki is a kind of online encyclopedia that users can contribute to. For an example, see http://www.officewiki.net for a wiki that documents the Office PIAs. Wikis use simple, easy-to-edit text files that any visitor to the wiki can edit without having to know HTML. These text files have simple representations of even complex elements like tables. Our console application will read a simple text file that specifies a table in wiki text format. It will then automate Word to create a Word table that matches the text file specification.

In the wiki text format, a table that looks like Table 2-1 is specified by the text in Listing 2-2.

Table 2-1: A simple table showing the properties and methods of Word's Add-in object.

Listing 2-2: A Wiki text representation of Table 1-4.

||Property or Method||Name||Return Type||
||Property||Application||Application||
||Property||Autoload||Boolean||
||Property||Compiled||Boolean||
||Property||Creator||Int32||
||Method||Delete||Void||
||Property||Index||Int32||
||Property||Installed||Boolean||
||Property||Name||String||
||Property||Parent||Object||
||Property||Path||String||

We will use Visual Studio .NET 2005 to create a console application. After launching Visual Studio, choose New Project... from the File menu. The new project dialog shows a variety of project types. Select the Visual C# node from the list of project types and select the Windows node under the Visual C# node. This is slightly counter intuitive as there is an Office node available as well, but the Office node only shows VSTO code behind document projects and the VSTO Outlook add-in project.

After you select the Windows node, you will see in the window to the right the available templates. Select the Console Application template. Name your console application project then press the OK button to create your project. In Figure 2-1 we've created a console application called WordWiki. Note that the new project dialog can have a different appearance than the one shown in Figure 2-1 depending on the profile you are using. In this book, we assume you are using the Visual C# Development Settings profile. You can change your profile by choosing Import and Export Settings... from the Tools menu.

Figure 2-1: Creating a console application from the New Project dialog.

Once you press the OK button, Visual Studio creates a console application project for you. Visual Studio displays the contents of the project in the Solution Explorer window as shown in Figure 2-2.

Figure 2-2: The Console application project "WordWiki" shown in Solution Explorer.

By default, a newly created console application references the assemblies System, System.Data, and System.Xml. We also need to add a reference to the Word 2003 PIA. We do this by right clicking on the References folder and choosing Add Reference... from the popup menu that appears. This shows the Add Reference dialog in Figure 2-3. Click on the COM tab and select the Microsoft Word 11.0 Object Library to add a reference to the Word 2003 PIA. Then click the OK button.

Figure 2-3: Adding a reference to the Microsoft Word 2003 PIA.

Visual Studio adds the reference to the Word 2003 PIA and adds additional references to the stdole, VBIDE, and Microsoft.Office.Core PIAs as shown in Figure 2-4. These additional PIAs are ones that the Word PIA depends on. Stdole is a PIA that contains the definition of some of the types that COM object models need. VBIDE is the PIA for the object model associated with the VBA editor integrated into Office. Microsoft.Office.Core (office.dll) is the PIA for common functionality shared by all the Office applications such as the object model for the toolbars and menus.

Figure 2-4: When you add the Word 2003 PIA, dependent PIA references are automatically added to the project.

Now that the proper references have been added to our console application, let's start writing code. Double click on Program.cs in the Solution Explorer window to edit the main source code file for the console application. If you have outlining turned on, you will see the text "using ..." at the top of the Program.cs file with a + sign next to it. Click on the + sign to expand out the code where the using directives are placed. Add the following three using directives so we can use objects from the Word PIA and the Microsoft.Office.Core PIA as well as classes in the System.IO namespace.

using Office = Microsoft.Office.Core;
using Word = Microsoft.Office.Interop.Word;
using System.IO;

We are now ready to write some real code that automates Word to create a table after reading a text input file in the wiki table format. The entire listing of our program is shown in Listing 2-3. Rather than explain every line of code in that listing, we will focus on the lines of code that automate Word. We assume the reader has some knowledge of how to read a text file in .NET and parse a string via the Split method. We will briefly touch on some objects in the Word object model here, but Chapters 6 through 8 cover the Word object model in much more detail.

The first thing we do in Listing 2-3 is declare a new instance of the Word application object by adding this line of code to Main method of our program class.

Word.Application theApplication = new Word.Application();

Although Word.Application is an interface, we are allowed to create a new instance of this interface because the compiler knows that the Word.Application interface is associated with a COM object that it knows how to start. When Word starts in response to an automation executable creating a new instance of its application object, it starts up without showing any windows. You can automate Word in this invisible state when you want to automate Word without confusing the user by bringing up the Word window. For this example, we want to make Word show its main window, and we do so by adding this line of code:

theApplication.Visible = true;

Next, we want to create a new empty Word document into which we will generate our table. We do this by calling the Add method on the Documents collection returned by Word's application object. The Add method takes four optional parameters that we want to omit. Optional parameters in Word methods are specified as omitted by passing by reference a variable containing the special value Type.Missing. We declare a variable called missing that we set to Type.Missing and pass it by reference to each parameter we wish to omit as shown here:

object missing = Type.Missing;
Word.Document theDocument = theApplication.Documents.Add(
ref missing,
ref missing, 
ref missing, 
ref missing);

With a document created, we want to read the input text file specified by the command line argument passed to our console application. We want to parse that text file to calculate the number of columns and rows. Once we know the number of columns and rows, we use the line of code below to get a Range object from the Document object. By passing our missing variable to the optional parameters, the Range method will return a range that includes the entire text of the document.

Word.Range range = theDocument.Range(ref missing, ref missing);

We then use our Range object to add a table by calling the Add method of the Tables collection returned by the Range object. We pass the Range object again as the first parameter to the Add method to specify that we want to replace the entire contents of the document with the table. We also specify the number of rows and columns we want.

Word.Table table = range.Tables.Add(
range, 
rowCount, 
columnCount, 
ref missing, 
ref missing);

The Table object has a Cell method that takes a row and column and returns a Cell object. The Cell object has a Range property that returns a Range object for the cell in question that we can use to set the text and formatting of the cell. The code that sets the cells of the table is shown below. Note that as in most of the Office object models, the indices are 1-based meaning they start with one as the minimum value rather than being 0-based and starting with zero as the minimum value.

for (columnIndex = 1; columnIndex <= columnCount; columnIndex++)
{
 Word.Cell cell = table.Cell(rowIndex, columnIndex);
 cell.Range.Text = splitRow[columnIndex];
}

Code to set the formatting of the table by setting the table to size to fit contents and bolding the header row is shown below. We use the Row object returned by table.Rows[1] which also has a Range property that returns a Range object for the row in question. Also, we encounter code that sets the first row of the table to be bolded. One would expect to be able to write the code table.Rows[1].Range.Bold = true, but Word's object model expects an int value (0 or 1) rather than a bool. This is one of many examples you will come across where the Office object models don't match .NET guidelines because of their origins in COM.

// Format table
table.Rows[1].Range.Bold = 1;
table.AutoFitBehavior(Word.WdAutoFitBehavior.wdAutoFitContent);

Finally, there is some code at the end of the program that forces Word to quit without saving changes:

// Quit without saving changes
object saveChanges = false;
theApplication.Quit(ref saveChanges, ref missing, ref missing);

If we don't write this code, Word will stay running even after the console application exits. Once you show the Word window by setting the Application object's Visible property to true, Word puts the lifetime of the application in the hands of the end user rather than the automating program. So even when the automation executable exits, Word will continue running. To force Word to exit we must call the Quit method on Word's Application object. If this program didn't make the Word window visible—say for example it created the document with the table then saved it to a file all without showing the Word window—it would not have to call Quit because Word would exit when the program exited and released all its references to the Word objects.

To run the console application in listing 2-3, you must create a text file that contains the text in Listing 2-2. Then pass the file name of the text file as a command line argument to the console application. You can set up the debugger to do this by right clicking on the WordWiki project in Solution Explorer and choosing Properties. Then click on the Debug tab and set the Command line arguments field to the name of your text file.

Listing 2-3: The complete WordWiki implementation.

using System;
using System.Collections.Generic;
using System.Text;
using System.IO;
using Office = Microsoft.Office.Core;
using Word = Microsoft.Office.Interop.Word;
 
namespace WordWiki
{
 class Program
 {
  static void Main(string[] args)
  {
   Word.Application theApplication = new Word.Application();
   theApplication.Visible = true;

   object missing = System.Type.Missing;
   Word.Document theDocument = theApplication.Documents.Add(ref missing, ref missing, ref missing, ref missing);

   TextReader reader = new System.IO.StreamReader(args[0]);

   string[] separators = new string[1];
   separators[0] = "||";
   int rowCount = 0;
   int columnCount = 0;

   // Read rows and calculate number of rows and columns
   System.Collections.Generic.List<string> rowList = new System.Collections.Generic.List<string>();
   string row = reader.ReadLine();

   while (row != null)
   {
    rowCount++;
    rowList.Add(row);

    // If this is the first row, calculate the number of columns
    if (rowCount == 1)
    {
     string[] splitHeaderRow = row.Split(separators, StringSplitOptions.None);
     columnCount = splitHeaderRow.Length - 2; // Ignore the first & last separator
    }

    row = reader.ReadLine();
   }

   // Create a table
   Word.Range range = theDocument.Range(ref missing, ref missing);
   Word.Table table = range.Tables.Add(range, rowCount, columnCount, ref missing, ref missing);
 
   // Populate table
   int columnIndex = 1;
   int rowIndex = 1;

   foreach (string r in rowList)
   {
    string[] splitRow = r.Split(separators, StringSplitOptions.None);

    for (columnIndex = 1; columnIndex <= columnCount; columnIndex++)
    {
     Word.Cell cell = table.Cell(rowIndex, columnIndex);
     cell.Range.Text = splitRow[columnIndex];
    }

    rowIndex++;
   }

   // Format table
   table.Rows[1].Range.Bold = 1;
   table.AutoFitBehavior(Word.WdAutoFitBehavior.wdAutoFitContent);

   // Wait for input from the command line before exiting
   System.Console.WriteLine("The table has been generated.");
   System.Console.ReadLine();

   // Quit without saving changes
   object saveChanges = false;
   theApplication.Quit(ref saveChanges, ref missing, ref missing);
  }
 }
}