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Keywords: Keywords are words that have a special meaning in VBA. They are often used as parts of VBA statements. For example Else is a keyword that is used in the If...Then...Else statement. You’re already familiar with the Set keyword, which is used in the Set statement.

Operators: VBA includes all the usual arithmetic operations, such as +, –, *, /, and ^. You can also use & to concatenate text strings. There are several logical operators, such as and, not, and or.

Statements: Statements help you create the flow of your code. You’re already familiar with the Set statement. Other statements are For Each...Next and If...Then...Else. These provide looping capabilities in VBA.

Remember that you can also get a list of objects and their properties and methods from the Object Browser, as explained earlier in this chapter.

Getting User Input

The examples used in this chapter weren’t very useful, partly because the routines provided no way to get user input for the properties of the objects they drew. There are two main ways to get user input — on the command line and via a dialog box. In this section, I explain how to get user input on the command line.

In order to use the user-input methods, you need to first use something called the Utility object. The Utility object belongs to the Document object and controls the methods that get user input. You can also use ThisDrawing, as in the following example.

Dim iReturn as Integer

iReturn = ThisDrawing.Utility.GetInteger(“Enter an integer: “)

Here you set a variable called iReturn equal to the integer that the user types on the command line. The prompt is Enter an integer:.

You can use this type of user input to get a pick point, a numeric value (such as the radius of a circle), a text string, or an object. Use this method when the input is short and sweet.

To avoid several prompts appearing on the same line, use vbCrLf, the carriage return/linefeed constant, at the beginning of a prompt, as in the following example:

prompt1 = vbCrLf & “Specify center point: “

Here’s an example that illustrates how to get user input on the command line:

Sub AddCircle()

Dim thePt As Variant

Dim theRadius As Double

Dim myCircle As AcadCircle

thePt = ThisDrawing.Utility.GetPoint(, vbCrLf & “Enter Center Point:”)

theRadius = ThisDrawing.Utility.GetReal(“Enter radius: “)

Set myCircle = ThisDrawing.ModelSpace.AddCircle(thePt, theRadius) End Sub

Table 37-3 lists some commonly used methods for getting user input. If you know the GET functions in AutoLISP, you’ll be familiar with these methods.

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Table 37-3: Common User-Input Methods

STEP-BY-STEP: Creating a VBA Routine That Gets User Input

1.Open a new AutoCAD drawing using the acad.dwt template.

2.To start a new project, choose Tools Macro VBA Manager. Click New and then click Visual Basic Editor.

3.Choose Insert Module and then choose Insert Procedure. Name it HappyFace and click OK.

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4. At the cursor, type the following:

pi = 3.1415

prompt = vbCrLf & “Specify center point: “ prompt2 = vbCrLf & “Specify radius: “

‘get center point from user

cen = ThisDrawing.Utility.GetPoint(, prompt)

rad = ThisDrawing.Utility.GetDistance(cen, prompt2)

‘draw head

Set cir = ThisDrawing.ModelSpace.AddCircle(cen, rad) ‘draw smile

dStart = 225 * pi / 180 ‘pi / 180 converts to radians DEnd = 315 * pi / 180

Set arc = ThisDrawing.ModelSpace.AddArc(cen, rad / 2, dStart, dEnd) ‘draw eyes

cen(0) = cen(0) - rad / 4 cen(1) = cen(1) + rad / 4

Set cir = ThisDrawing.ModelSpace.AddCircle(cen, rad / 8) cen(0) = cen(0) + rad / 2

Set cir = ThisDrawing.ModelSpace.AddCircle(cen, rad / 8)

5.Change the module name to HappyFace.

6.Choose Save from the VBA IDE Standard toolbar and save the VBA project as ab37-02. dvb in your AutoCAD Bible folder.

7.Return to your drawing and choose Tools Macro Macros. In the Macro dialog box, choose HappyFace and click Run.

8.Respond to the prompts. HappyFace draws the circle with the center point and radius you specify.

You don’t need to save your drawing.

The previous example uses GetDistance rather than GetReal to enable the user to select the radius of the circle with the mouse. The center point you previously selected feeds into the GetDistance function. Also, there are calculations to convert degrees to radians. The location and size of the eyes and smile are relative to the center and radius.

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Creating Dialog Boxes

One of the main characteristics of VBA is the ease with which you can create dialog boxes to get user input. Whenever you need input that is more complex than you can get using the Get methods, you should use a dialog box. You can also use a dialog box to create a more professional look or for ease of use.

When working with a dialog box, you generally create the dialog box first and then attach code to the dialog box buttons. You then use a second module to display the dialog box. Running the second module then controls the entire routine.

In VBA, a dialog box is called a user form. To create one, choose Insert UserForm. VBA creates a blank user form that will become your dialog box. Simultaneously, the Toolbox toolbar appears. If this toolbar covers up some other part of your screen, drag it to one side. Your screen looks like Figure 37-6.

Figure 37-6: The VBA IDE with a blank user form and the

Toolbox toolbar.

Understanding the Toolbox toolbar

The Toolbox toolbar contains the tools you need to create a dialog box. These are the familiar controls you see in the dialog boxes you use all the time, such as text boxes, list boxes, check boxes, and so on.

Table 37-4 explains the Toolbox toolbar buttons.

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Changing dialog-box properties

After you insert a user form, you should name it. Find the Name property in the Properties window and change it from UserForm1 (the default name) to any useful name you want. You might find it useful to use the word form in the name. For example, for a routine to draw a circle, you could call the user form formCircle.

Figure 37-7 shows the property box when you insert a user form. You can easily change the dialog box’s properties in the property box.

One property you’ll want to change is the Caption property of the dialog box. The dialog box should have a caption that summarizes its purpose. When you type the new caption in the property box, the caption on the dialog box changes at the same time.

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Figure 37-7: When you insert a user form (dialog box), the Properties window lists all its properties.

Adding dialog-box controls

One of the more commonly used controls is the command button. A command button is a button you click in the dialog box to execute an action. The most familiar command buttons are the OK and Cancel buttons.

Add a command button

To add a command button, click CommandButton on the Toolbox toolbar. Move your cursor over the dialog box and drag to create a button. Figure 37-8 shows a dialog box with a new command button. The selection border and handles indicate that the button is a selected

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object. You can move the button by dragging it. You can resize the button by dragging one of the handles. Add all the command buttons you need. Don’t forget to include at least a Cancel button. Many dialog boxes also have an OK button. If you know in advance all the controls you’ll need, you can add them all at once.

Figure 37-8: A dialog box with one selected command button.

Tip There’s an art to laying out a dialog box so that it’s clear and easy to understand. After a while you’ll get the hang of it. Pay more attention to the dialog boxes you use every day to pick up some design pointers.

Just as the dialog box has properties, each control on the dialog box has properties. When a control such as a command button is selected, you see its properties in the Properties window. You generally would change at least the caption and the name of a command button. It’s a good idea to change the names to something meaningful rather than using the default name. For example, instead of CommandButton1, use something such as cmdDrawBox or cmdOk.

Write the VBA Code for a command button

After you create a command button, you can attach VBA code to it. To attach VBA code to a control, double-click the control. The text editor opens with the Sub and End Sub lines already entered for you. Type the code you want to attach to the button.

VBA dialog boxes are modal by default, which means that they must be closed before AutoCAD can do anything further. To close a dialog box after your VBA code has run, use Unload Me at the end of a routine.

To run VBA code attached to a dialog box, you need to show the dialog box so you can use it — click a command button, type in text, and so on. The VBA IDE creates private subroutines for each dialog box control. To show the dialog box, start a new module and create code that looks like the code in this example.

Sub DrawArc()

FormArc.Show

End Sub

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FormArc is the name of the user form in this example. Don’t forget to name the user form in the Properties window. Also, remember to name the module, because the module name is what appears in the Macro dialog box when you want to run the routine.

Add a label

A command button is quite simple. You just click it, and it performs. You can label its function right on the command button. However, most other controls require some more explanation. For example, if you want the user to type in text, you need a text box. However, a text box has no caption. Therefore, you need to add instructions to the user. A dialog box may also need other instructions to clarify the purpose of the controls, which responses are required, and so on.

You add instructions with the Label tool on the Toolbox toolbar. Click Label and drag a rectangle on your dialog box. Then type the label. You can resize or move the label as needed.

Add other dialog-box controls

The code for some of the dialog-box controls can be quite complex. For example, to create a list box that enables the user to choose from an existing list of options, you’d probably create the list of options in advance. For help on creating dialog boxes, choose Help Microsoft Visual Basic Help. On the Contents tab, double-click Microsoft Forms Reference, then Microsoft Forms Object Model Reference. From there, you may want to double-click Objects, Collections, and Controls. You can double-click a control, such as the ListBox control, and read more about it. The specific controls also offer hyperlinks to examples you can look at.

STEP-BY-STEP: Creating a Dialog Box with a Command Button

1.Open a new drawing in AutoCAD using the acad.dwt template. Choose Tools Macro Visual Basic Editor.

2.Choose Insert UserForm. If the Toolbox toolbar covers the user form or project window, drag it to the right.

3.With the user form active (click its title bar to make it active), change the Name property of the user form to frmArc in the Properties window.

4.Change the Caption property of the user form to Draw an arc. Watch the caption of the user form change as you type.

5.Choose CommandButton on the Toolbox toolbar. (It’s the last button in the second row. If you don’t see the Toolbox toolbar, click in the user form on the right side of your screen.) Move the cursor over the user form and drag to create a wide button across the upper center of the user form.

6.Change the Caption property of the button to Draw the Arc! Change the name property to cmdDrawArc.

7.Again, choose CommandButton on the Toolbox toolbar. Create a smaller button below the first one near the right side of the user form.

8.Change the Caption property of the smaller button to Cancel. Change its name property to cmdCancel. Your dialog box should look like the one in Figure 37-9.

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Figure 37-9: A simple dialog box created in VBA.

9.Double-click the larger button. In the text editor, type the following code at the cursor’s current location between the Private Sub and End Sub statements:

‘declare variables Dim startang As Double Dim endang As Double

Dim ctr(0 To 2) As Double Dim rad As Double

Dim newarc As Object ‘specify arc parameters startang = 0

‘angles are in radians. endang = 100

ctr(0) = 5 ctr(1) = 2 ctr(2) = 0 rad = 2 ‘draw arc

Set newarc = ThisDrawing.ModelSpace.AddArc(ctr, rad, startang, endang) ‘close dialog box

Unload Me

10.From the left (Object) drop-down list at the top of the text editor, choose cmdCancel to add the code for the second button. In the space below the start of the subroutine

(Private Sub cmdCancel_Click()), type Unload Me.

11.Choose Insert Module. In the new text editor, type the following to display the dialog box.

Sub DrawArc() frmArc.Show

Visual Basic places the End Sub statement for you after the code.

12.In the Properties window, change the module’s name to DrawArc.

13.Click Save on the toolbar and save the file in your AutoCAD Bible folder as ab37-03.dvb.

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14.Return to your drawing. Choose Tools Macro Macros. In the Macro dialog box, choose DrawArc and click Run.

15.Click the large button. AutoCAD draws the arc.

Getting user input for a circle radius

Here’s another example of a routine that draws a circle, but here you get user input for the radius using the VAL function. The VAL function returns a numerical value from a text string. Here you create a text box that enables users to type in a radius. The VAL function converts the string in the text box to a number and uses it as the circle’s radius. Follow these steps:

1.Open AutoCAD with a new drawing using the acad.dwt template. Open the VBA IDE.

2.Choose Insert UserForm.

3.In the Properties window, change the name of the form to frmDrawCircle and the caption to Draw a Circle Demo.

4.From the Toolbox toolbar, choose Label and drag a small rectangle on the left side of the form, around the middle.

5.Change the caption to Radius.

6.Choose Textbox on the Toolbox toolbar and drag a box on the form to the right of the label.

7.Change the name to txtRadius.

8.Choose CommandButton on the Toolbox toolbar and drag a larger box at the top-center of the form.

9.Change the name to cmdDrawCircle and the caption to Draw Circle.

10.Double-click this command button to bring up the code editor in the cmdDrawCircle_Click () subroutine.

11.Add the following lines:

Dim dCenter(0 To 2) As Double Dim dRadius As Double

Dim myCircle as AcadCircle

dCenter(0) = 0# dCenter(1) = 0# dCenter(2) = 0#

dRadius = Val(txtRadius)

Set myCircle = ThisDrawing.ModelSpace.AddCircle(dCenter, dRadius) myCircle.Update

12.Close the code window. Save the routine if you want. On the VBA IDE menu, choose Run Run Sub/UserForm. Visual Basic returns you to your drawing and displays the dialog box. Enter a number for the radius and click the Draw Circle command button.

13.Add as many circles as you like. Click the Close box of the dialog box when you’re done.