Chapter 24: Printing

Visual Basic .NET provides several good tools for printing. String formatting objects enable you to determine how text is wrapped and truncated if it won’t fit in a printing area. Methods provided by Graphics objects enable you to easily scale, rotate, and translate drawing commands.

The basic process, however, seems somewhat backward to many programmers. Rather than issuing commands to a printer object, a program responds to requests to draw pages generated by a PrintDocument object. Instead of telling the printer what to do, the program responds to the PrintDocument object’s requests for data.

In some cases, generating a printout using only Visual Basic commands can be difficult. The following section explains alternative methods for generating a printout and tells when you might want to use those methods. If you just want to print several pages of text, it’s often easier to pull the text into Microsoft Word or some other application that specializes in formatting text rather than writing your own.

In other cases, however, you cannot take an easy way out. If the program generates very complex images and graphs, or produces text that is positioned and formatted in a complex manner, you probably need to work through the Visual Basic printing system. The rest of this chapter explains the techniques that you use to generate printouts in Visual Basic. It shows how to draw graphics and text on the printer and how to scale and center the results.

How Not to Print

Although Visual Basic provides many tools for arranging graphics on a printout, it does not always provide the best approach to printing. The general method for printing in Visual Basic requires you to generate each page of output in turn. For simple documents (such as a line drawing containing a few lines and circles on a single page), this is easy.

On the other hand, suppose that you want to print several dozen pages of text interspersed with tables and pictures. Figuring out where each page break should be placed and how the text should flow around the tables and pictures could be a huge undertaking. To really do the job right, you might need to consider orphan lines (when the first line of a paragraph sits at the bottom of a page), widow lines (the last line of a paragraph sits at the top of a page), orphan and widow words (when the first or last word sits on a separate line), inserting extra space between words to make a line look nicer, page numbers, headers and footers, hyphenation, different left and right margins, mirrored margins, page gutters, bulleted lists, indentation and justification, different font sizes and styles, and a host of other issues.

Word processing and text-formatting applications such as Microsoft Word spend a great deal of effort on these issues - effort that you probably don’t want to duplicate. In fact, Word is so good at handling these issues that you should consider using it to print your output instead of writing an elaborate Visual Basic program to do it.

If your output is simple text, you can drop it into a text file and then use Word to open, format, and print it. For printouts that you don’t need to generate too frequently, and for printouts where the user may want to edit the results before printing anyway, this is a simple, flexible solution that doesn’t require you to write, debug, and maintain a lot of complicated formatting code.

For more elaborate printouts, programs such as Word may still be useful. Using Visual Studio Tools for Office (VSTO), you can open a Microsoft Word application and control it from your Visual Basic program. Your program can use the Word object model to add text, insert pictures, build tables, set page printing options, and even print the result. You can then save the document for later use or discard it.

Using VSTO, not only can you control Microsoft Word, but you can also use the other Microsoft Office applications. For example, you can load information into Excel so that you can use its tools to analyze and graph the data, copy information into Access for analysis by other database applications, or compose email messages in Outlook.

VSTO is relatively complicated and outside of the scope of this book, so it isn’t described here. For more information, see the VTSO web site at msdn2.microsoft.com/office/aa905533.aspx. You can download Visual Studio 2005 Tools for Office Second Edition at www.microsoft.com/downloads/details.aspx?familyid=. You can also learn more in a book about VSTO such as Professional VSTO 2005: Visual Studio 2005 Tools for Office by Alvin Bruney (Wiley, 2006).