Microsoft Excel 2016 BIBLE (2016)
Programming Excel with VBA
Creating Custom Excel Add-Ins
IN THIS CHAPTER
1. Understanding add-ins
2. Converting a workbook to an add-in
For developers, one of the most useful features in Excel is the capability to create add-ins. This chapter discusses this concept and provides a practical example of creating an add-in.
What Is an Add-In?
Generally speaking, an add-in is something that's added to software to give it additional functionality. Excel includes several add-ins, including the Analysis ToolPak and Solver. Ideally, the new features blend in well with the original interface so that they appear to be part of the program.
Excel's approach to add-ins is quite powerful: any knowledgeable Excel user can create add-ins from workbooks. The type of add-in covered in this chapter is basically a different form of a workbook file. Any Excel workbook can be converted into an add-in, but not every workbook is a good candidate for an add-in.
What distinguishes an add-in form a normal workbook? Add-ins, by default, have an .xlam extension. In addition, add-ins are always hidden, so you can't display worksheets or chart sheets that are contained in an add-in. But you can access its VBA procedures and display dialog boxes that are contained on UserForms.
The following are some typical uses for Excel add-ins:
· Store one or more custom worksheet functions. When the add-in is loaded, you can use the functions like any built-in worksheet function.
· Store Excel utilities. VBA is ideal for creating general-purpose utilities that extend the power of Excel. The Power Utility Pak that I created is an example.
· Store proprietary macros. If you don't want end users to see (or modify) your macros, store the macros in an add-in and protect the VBA project with a password. Users can use the macros, but they can't view or change them unless they knows the password. An additional benefit is that the add-in doesn't display a workbook window, which can be distracting.
As previously noted, Excel ships with several useful add-ins, and you can acquire other add-ins from third-party vendors or online. In addition, Excel includes the tools that enable you to create your own add-ins. I explain this process later in this chapter (see “Creating Add-Ins”).
Working with Add-Ins
The best way to work with add-ins is to use the Excel Add-In Manager. To display the Add-In Manager, follow these steps:
1. Choose File Options. The Excel Options dialog box appears.
2. Select the Add-Ins category.
3. At the bottom of the dialog box, select Excel Add-Ins from the Manage list and then click Go.
The Add-Ins dialog box, shown in Figure 45.1, appears. The dialog box contains all the add-ins that Excel knows about. The add-ins that are checked are open. You can open and close add-ins from this dialog box by selecting or deselecting the check boxes.
Figure 45.1 The Add-Ins dialog box.
Pressing Alt+T followed by I is a much faster way to display the Add-Ins dialog box. Or, if the Developer tab is visible, choose Developer Add-Ins Add-Ins.
You can also open most add-in files by choosing File Open. After an add-in is opened, however, you can't choose File Close to close it. The only way to remove the add-in is to exit and restart Excel or to write a macro to close the add-in. Therefore, you're usually better off opening the add-ins by using the Add-Ins dialog box.
The user interface for some add-ins (including those included with Excel) may be integrated into the Ribbon. For example, when you open the Analysis ToolPak add-in, you access these tools by choosing Data Analysis Data Analysis.
If you open an add-in created in a version prior to Excel 2007 (an *.xla file), any user interface modifications made by the add-in will not appear as they were intended to. Instead, you must access the user interface items (menus and toolbars) by choosing Add-Ins Menu Commands or Add-Ins Custom Toolbars.
Why Create Add-Ins?
Most Excel users have no need to create add-ins. However, if you develop spreadsheets for others — or if you simply want to get the most out of Excel — you may be interested in pursuing this topic further.
Here are some reasons you may want to convert your Excel workbook application to an add-in:
· To avoid confusion: If an end user loads your application as an add-in, the file isn't visible in a window — and, therefore, is less likely to confuse novice users or get in the way. Unlike a hidden workbook window, an add-in can't be unhidden.
· To simplify access to worksheet functions: Custom worksheet functions stored in an add-in don't require the workbook name qualifier. For example, if you have a custom function named MOVAVG stored in a workbook named Newfuncs.xlsm, you have to use syntax such as the following to use this function in a different workbook:
· However, if this function is stored in an add-in file that's open, the syntax is much simpler because you don't need to include the file reference:
· To provide easier access: After you identify the location of your add-in, it appears in the Add-Ins dialog box and can display a friendly name and a description of what it does.
· To permit better loading control: You can automatically open add-ins when Excel starts, regardless of the directory in which they're stored.
· To omit prompts when unloading: When an add-in is closed, the user never sees the Save Change In prompt because changes to add-ins aren't saved unless you specifically do so from the VB Editor window.
Technically, you can convert any workbook to an add-in. Not all workbooks benefit from this conversion, though. In fact, workbooks that consist only of worksheets (that is, not macros or custom dialog boxes) become unusable because add-ins are hidden.
Workbooks that benefit from conversion to an add-in are those with macros. For example, you may have a workbook that consists of general-purpose macros and functions. This type of workbook makes an ideal add-in.
The following steps describe how to create an add-in from a workbook:
1. Develop your application and make sure that everything works properly.
2. (Optional) Add a title and description for your add-in. Choose File Info and click Show All Properties at the bottom of the right panel. Enter a brief descriptive title in the Title field, and then enter a longer description in the Comments field. Although this step isn't required, it makes installing and identifying the add-in easier.
3. (Optional) Lock the VBA Project. This step protects the VBA code and UserForms from being viewed. You do this in the VB Editor; choose Tools <Project Name> Properties (where <Project Name> corresponds to your VB Project name). In the dialog box, click the Protection tab and select Lock Project for Viewing. If you like, you can specify a password to prevent others from viewing your code.
4. Save the workbook as an add-in file by choosing File Save As and selecting Excel Add-In (*.xlam) from the Save As Type drop-down list. By default, Excel saves your add-in in your AddIns directory. You can override this location and choose any directory you like.
After you save the workbook as an add-in, the original (non-add-in) workbook remains active. If you're going to install the add-in and test it, you should close this file to avoid having two macros with the same name.
After you create the add-in, you need to install it:
1. Choose File Options Add-Ins.
2. Select Excel Add-Ins from the Manage drop-down list and then click Go. The Add-Ins dialog box appears.
3. Click the Browse button to locate the XLAM file that you created, which installs the add-in. The Add-Ins dialog box uses the descriptive title that you provided in the Properties panel.
You can continue to modify the macros and UserForms in the XLAM version of your file. Because the add-in doesn't appear in the Excel window, you save your changes in the VB Editor by choosing File Save.
An Add-In Example
This section discusses the steps to create a useful add-in from the change case.xlsm workbook that I cover in Chapter 41, “Creating UserForms.” This workbook contains a UserForm that displays options that change the text case of selected cells (uppercase, lowercase, or proper case). Figure 45.2 shows the add-in in action.
Figure 45.2 This dialog box enables the user to change the case of text in the selected cells.
This book's website at www.wiley.com/go/excel2016bible contains the original version of the workbook (change case.xlsm), plus a version after it was converted to an add-in (change case.xlam). Neither file is locked, so you have full access to the VBA code and UserForm.
This workbook contains one worksheet, which is empty. Although the worksheet is not used, it must be present because every workbook must have at least one sheet.
It also contains one VBA module and one UserForm.
The Module1 code module contains one procedure that displays the UserForm. The ShowChangeCaseUserForm procedure checks the type of selection. If a range is selected, the dialog box in UserForm1 appears. If anything other than a range is selected, a message box is displayed:
Sub ShowChangeCaseUserForm ()
If TypeName(Selection) = "Range" Then
MsgBox "Select some cells."
About the UserForm
Figure 45.3 shows the UserForm1 form, which has five controls: three OptionButton controls and two CommandButton controls. The controls have descriptive names, and the Accelerator property is set so that the controls display an accelerator key (for keyboard users). The option button with the Upper Case caption has its Value property set to TRUE, which makes it the default option.
Figure 45.3 The custom dialog box.
Refer to Chapter 41 for details about how the code works.
Testing the workbook
Before you convert a workbook to an add-in, test it when a different workbook is active to simulate what happens when the workbook is an add-in. Remember that an add-in is never the active workbook, and it never displays any of its worksheets.
To test it, save the XLSM version of the workbook, close it, and then reopen it. With the workbook open, activate a different workbook, select some cells that contain text, and then press Alt+F8 to display the Macros dialog box. Execute the ShowChangeCaseUserFormmacro and try all the options.
Adding descriptive information
Adding descriptive information is recommended but not necessary. Choose File Info and click Show All Properties at the bottom of the right panel (see Figure 45.4). Enter a title for the add-in in the Title field. This text appears in the Add-Ins dialog box. In the Comments field, enter a description. This information appears at the bottom of the Add-Ins dialog box when the add-in is selected.
Figure 45.4 Adding descriptive information about your add-in.
Creating the user interface for your add-in macro
At this point, the future add-in is missing one key component: a way to execute the macro that displays the UserForm. The easiest solution is to provide a shortcut key that executes the macro. Ctrl+Shift+C is a good key combination. Here's how to do it:
1. In Excel, choose Developer Code Macros (or press Alt+F8). The Macro dialog box appears.
2. In the Macro Name list, select the macro named ShowChangeCaseUserForm.
3. Click the Options button. The Macro Options dialog box appears.
4. Specify Ctrl+Shift+C as the shortcut key, and click OK.
5. Click Cancel to close the Macro dialog box.
Make sure you save the workbook after making this change.
Protecting the project
In some situations (such as a commercial product), you may want to protect your project so that others can't see the source code. To protect the project, follow these steps:
1. Activate the VB Editor.
2. In the Project window, click the project.
3. Choose Tools <Project Name> Properties. The VB Editor displays its Project Properties dialog box.
4. Select the Protection tab (as shown in Figure 45.5).
Figure 45.5 The Protection tab of the Project Properties dialog box.
5. Select the Lock Project for Viewing check box.
6. Enter a password (twice) for the project.
7. Click OK.
Creating the add-in
To save the workbook as an add-in, follow these steps:
1. Switch to the Excel window and activate your workbook.
2. Choose File Save As.
3. Select Microsoft Excel Add-In (*.xlam) from the Save as Type drop-down list.
4. Enter a name for the add-in file, and then click OK. By default, Excel saves the add-in in your AddIns directory, but you can choose a different directory if you like.
Installing the add-in
Now it's time to try the add-in. Make sure the XLSM version of the workbook is not open, and then follow these steps:
1. Choose File Excel Options Add-Ins.
2. Select Excel Add-Ins from the Manage drop-down list, and click Go. The Add-Ins dialog box appears.
3. Click the Browse button and locate and select the change case.xlam add-in that you just created. The Add-Ins dialog box displays the add-in in its list. Notice that the information you provided in the Properties panel appears here.
4. Click OK to close the dialog box and open the add-in.
When the add-in is installed, you can access it by pressing Ctrl+Shift+C. Another option is to add a new item to your Quick Access toolbar or to the Ribbon.
See Chapter 24, “Customizing the Excel User Interface,” for information about customizing Excel's user interface.