• Chapter 3
  • Controls and Properties
    • Creating New Applications
    • Controls Provide the Interface
      • Placing Controls
        • Figure 3.1.
        • Figure 3.2.
      • Sizing and Moving Controls
        • Figure 3.3.
      • Setting Properties
        • Figure 3.4.
    • Giving Your Users Help
      • Figure 3.5.
      • Figure 3.6.
      • Figure 3.7.
    • Named Literals
      • Figure 3.8.
    • Take a Break!
      • Figure 3.9.
      • Figure 3.10.
      • Figure 3.11.
    • Summary
    • Q&A
    • Workshop
      • Quiz
      • Exercises

Chapter 3

Controls and Properties

Nobody can master Visual Basic until he masters controls and properties. The form is the placeholder for the controls, and the controls are the really important parts of any application. Many of the properties require different kinds of values, and you will learn in this hour's lesson how to set those values.

Before you finish this lesson, you also will have created your very first application from scratch without the aid of the VB Application Wizard. You will have created a new project, sized the form, added controls, set control properties, and even written an event procedure using the Visual Basic programming language! As you'll soon see, Visual Basic makes all those tasks simple.

The highlights of this hour include

• What steps are required for application creation

• How to place and size controls

• Why various properties require different setting methods

• Which naming prefixes work best

• Why your application's tooltips give users added help

Creating New Applications

When you create an application from scratch, instead of using the VB Application Wizard to generate the program shell, you control every aspect of the application's design and you place all the program's controls on the form yourself. When you place those controls, you must name the controls, position the controls, set control properties, adjust the control sizes, and hook up all the event procedure code that goes with each control.

All this may sound daunting, but Visual Basic makes things as simple as possible. Although the task is not quite as simple as running the wizard, you have the power to create the exact application you need. Newcomers need to learn how to create applications without the wizard so they can fully master all the ins and outs of Visual Basic.

To create a new application from scratch, start Visual Basic and double-click the icon labeled Standard EXE. The blank Form window appears in the work area's upper-left corner next to the toolbox, ready for you to begin creating the application by placing the controls.

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TIP: The default Form window size is fairly small, especially when you realize that the Form window holds the application's background. Most applications appear either full-screen or in an initial window much larger than the Form window size that appears. Therefore, one of the first tasks you will usually perform is to increase the Form window's size.

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If you double-click the Form window's title, Visual Basic expands the Form window to a full- screen size. However, with your toolbox and other windows on the screen, you'll have to use the scrollbars to access various parts of the form. Of course, if your application is full screen, you'll need to work with the scrollbars to add controls to the full form.

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NOTE: This guide's Form windows typically remain a size at which you can see all the form as well as the surrounding windows. Therefore, most of the applications in this guide contain fairly small Form windows. The guide's Form windows will be larger than the default size that appears when you first start Visual Basic, but the Form windows will be far smaller than full screen.

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Controls Provide the Interface

The controls you select for your application's form are important because the controls (also called tools) provide the application interface for your users. Users interact with your application by clicking the controls and entering text in the controls. Placing and sizing controls are perhaps the two most important tasks you can master at this point.

Placing Controls

Once you increase the Form window to a reasonable size that your application requires, your job is to place controls on the form. Use either of these two methods for placing controls on the form:

1. Double-click any control on the Toolbox window to place that control on the Form window. As Figure 3.1 shows, the control appears in the center of the Form window.

Figure 3.1. The command button appears in the center of the Form window.

If a control appears in the center of the form already, the new control will overwrite the existing control. You can drag the new control to a different location, however. The eight sizing handles (the small boxes that appear around a selected control) indicate that the control is selected. If several controls appear on the Form window, the selected controls will display their sizing handles. (Typically, only one control will be selected at any one time but you can select multiple controls by holding the Ctrl key and clicking several controls.)

2. If you click a toolbox control once, the toolbox highlights the control. If you then move the mouse cursor to the Form window, the mouse cursor turns into a crosshair indicating that you can place the selected control anywhere on the form. Whereas a control appears in the center of the Form window automatically as soon as you double-click the control, a selected control appears only when you click and drag your mouse crosshair on the Form window. The final control appears when you release the mouse.

The advantage of using this approach to placing controls over the first approach is that you don't have to move and resize the control after you've placed it. Figure 3.2 shows Figure 3.1's command button placed in the center of the form with a double-click as well as a new command button placed on the form by dragging the control as described here. You can place the control exactly where you want it and at the size you want it when you drag the control onto the form.

Figure 3.2. The second command button is placed and sized immediately.

Sizing and Moving Controls

You can change the size of only a selected control. The eight sizing handles are the key to resizing the control. You can drag any of the eight sizing handles in any direction to increase or decrease the control's size. Of course, if you placed a control on the form by dragging the control, you won't need to resize the control as often as you will if you double-clicked the toolbox tool to place the control.

You can move a selected control to any area of the Form window by dragging the control with your mouse. Once you click to select a control, click the control and hold down the mouse button to drag the control to another part of the Form window.

Sometimes you may want to drag several controls to a new location as a group. For example, perhaps you've placed a set of command buttons at the bottom of a form and after adjusting the Form window's size, you determine that you need to move the buttons down some. Although you can move the command buttons one at a time, you can more quickly select all the command buttons and move them as a group.

As stated earlier, you can select more than one control by holding the Ctrl key as you click a control. (Much of the Windows interface, such as Explorer and the Windows Desktop, lets you select multiple files and icons the same way as Visual Basic lets you select multiple controls.)

In addition, you can lasso the controls by dragging a selection rectangle around the controls you want to select as a group. When you release your mouse, the controls within the selected region will be selected, like those shown in Figure 3.3.

Figure 3.3. Selecting multiple controls when you want to move the entire group at once.

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TIP: Remember how to select multiple controls if you find yourself needing to change other properties beside the location of controls. If you select multiple controls before changing a control property, all controls in the selected range will take on that new property value. You can only change the common properties that appear in all of the selected controls.

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Setting Properties

As you add controls to the Form window, the Properties window updates to show the properties for the currently selected control. The selected control is usually the control you last placed on the form. Visual Basic lets you see a control's properties in the Properties window by clicking to select the control or by selecting the control from the Properties window's drop-down list box, as shown in Figure 3.4.

Figure 3.4. Selecting the control to work with.

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NOTE: Visual Basic programmers often use the generic term object to refer to controls, forms, menus, and various other items on the screen and in the code.

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Scroll the Properties window to see the various properties for the selected controls. Each kind of control supports the same set of properties. Therefore, every command button you place on the form supports the same properties (and events as well) as every other command button, but option buttons and text boxes support different sets of properties than command buttons.

The Left, Top, Height, and Width properties are about the only properties you can set without accessing the Properties window. As you size and move a control into place, Visual Basic updates the Left, Top, Height, and Width properties according to the control's placement on the Form window and the control's size. As with the form location and size measurements, these properties appear in twips (unless you specify a different value in the ScaleMode property). Left indicates how far from the form's left edge the control appears, Top indicates how far from the top of the form the control appears, and the Height and Width properties indicate the control's size.

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NOTE: Even the form has properties. Click your Form window and look at the Properties window. The form will be the selected object at the top of the Properties window (Form1 is the default name for an application's initial form).

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After you place and size a control, the first property you should modify is the Name property. Although Visual Basic assigns default names to controls when you place the controls on the Form window, the default names don't indicate the control's true purpose in your application. In addition, the default names don't contain the three-letter prefix that describes the control you learned about in Hour 2, "Analyzing Visual Basic Programs."

For your reference, Table 3.1 lists common prefixes used for control names. When you name your Form window's controls, you'll appreciate later that you took the time to type the three-letter abbreviations at the beginning of the names because you will be less likely to assign a text box a property that belongs to a command button control inside an event procedure. (Such an assignment will cause a runtime error.)

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NOTE: The Name property is so important that Visual Basic lists the Name property first (as (Name) inside parentheses) in the Properties window instead of alphabetically in the Properties window, where the other properties reside.

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New Term: A tooltip is a pop-up description box that appears when the user rests the mouse pointer over a control.

Some property values you set by typing the values directly in the Properties window. For example, to enter a value for a control's ToolTipText property, click once on the Properties window's ToolTipText property and type the tooltip text.

The tooltip is a great feature that helps your users and is as easy to implement as typing text into the control's ToolTipText property. Most applications since the introduction of Windows 95 include tooltips, and there's no reason why your applications should not include them as well.

Figure 3.5 shows a tooltip that appears in Visual Basic when you rest the mouse pointer over the Form Layout window toolbar button. The best time to add tooltip text is when you adjust a new control's properties because you are more likely to remember the primary purpose for the control. Often, when programmers plan to add such items later once they "complete" the application, the items to be added, especially helpful items such as tooltips, are not added.

Figure 3.5. The tooltip pops up to describe an object.

If you want to change a property value, such as the Name property, you can click the Name property and enter a new name. As you type, the new name replaces the original name. If instead of clicking you double-click the property, Visual Basic highlights the property value and lets you edit the existing value by pressing your cursor keys and using Insert and Delete to edit the current property value.

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TIP: As you select a property, read the text that appears at the bottom of the Properties window. The text describes the property and serves as a reminder about what some of the more obscure properties do.

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Some properties require a selection from a drop-down list box. For example, Figure 3.6 shows a command button's Visible property's drop-down list box. The Visible property can either be True or False. No other values work for the property, so Visual Basic lets you select from one of those two values when you click the property value to display the down arrow and open the drop-down list box.

Figure 3.6. Some properties require a selection from a list box.

If an ellipsis (...) is displayed when you click the property value, such as the Font property when you click the current Font property's value, a dialog box opens when you click the ellipsis. A Font property is more than just a style name or size. The control's Font property can take on all kinds of values and the Font dialog box that appears from the click of the ellipsis lets you specify all available Font property parts. When you close the dialog box, the compound property is set to the dialog box's specific values.

Some programmers prefer the Categorized view of the Properties window. By default, the Properties window displays its properties alphabetically (with a possible exception at the top of the Properties window, such as the Name property). When you click the Categorized tab above the property values, the Properties window changes to show the properties in an Explorer tree view such as the one in Figure 3.7.

Figure 3.7. These property values appear by category type.

If you needed to change all of a control's appearance values, such as Color and Caption, you could expand the Categorized view's Appearance entry to display all the appearance values together. You then can more quickly change the appearance than if you had to search through the alphabetical listing of properties.

As you can see, placing a control requires much more involvement with property values than simply moving and sizing the control. You rarely if ever have to change all of a control's properties because many of the default values work fine for most applications. Nevertheless, many property values work to make the control unique to your specific application.

A named literal, also called a named constant, is a special named value that represents a fixed value. Visual Basic comes with several named literals and you'll use many of them in your programs to assign values to controls at runtime.

Consider the drop-down list box that appears when you click on a command button's MousePointer property (see Figure 3.8). The MousePointer property requires a value from 0 to 15 (or 99 for a custom value). When you set property values at design time, you simply select from the list, and the descriptions to the right of the numeric values explain what each value is for. When programming, you will be able to assign property values to properties when the user runs the program. Although you can assign 2 to the property value to change the mouse cursor to a crosshair during one part of the running application, your code will be better if you assign the named literal vbCrosshair. Although vbCrosshair is longer to type, you will know what you assigned when you later look at the project.

We're getting slightly ahead of ourselves discussing runtime property values that change inside the code such as event procedures. Nevertheless, keep named literals in mind as you assign values to the Properties window at design time. The named literals often closely match their Properties window counterparts. When you're ready to use named literals in subsequent lessons, this guide describes the ones available for the controls being discussed.

Figure 3.8. You can assign a named literal to this property.

In this section, you are going to create a project from scratch without the help of the VB Application Wizard. You'll create a new project, assign controls, and write event procedure code to hook everything together. The final application will be simple, but you'll have little trouble understanding the application now that you've become more familiar with properties and event procedures.

To create your first application, follow these steps:

1. Create a new project by selecting File | New Project and double-clicking the Standard EXE icon. Don't save any changes from earlier in this lesson if you were following along during the discussion of command buttons and control placement.

2. Change the form's Name property to frmFirst and change its Caption property to My First Application. The form's Caption property text appears in the title bar when you run the application.

3. Expand the Form window to these property values: Height 7380 and Width 7095. You can either drag the Form window's sizing handles until the Form window's size coordinates to the right of the toolbar read 7095x7380 or you can set these two property values yourself by changing the values in the Properties window. If you drag the Form window to obtain this size, you can approximate the coordinates described here; you don't have to size your Form window exactly to 7,095 by 7,380 twips.

4. Click the Label control once. As you learned in Hour 1, "Visual Basic at Work," the Label control is the tool with the capital letter A on the toolbox. When you click the Label control, Visual Basic shows the control depressed as if it were a command button.
5. Move the mouse pointer onto the Form window and drag a Label control toward the top of the Form window in the approximate location you see in Figure 3.9.

6. Change the label's Name property to lblFirst. Change the label's Caption property to VB is fun.

7. Click the label's Font property value to display the ellipsis. Click the ellipsis to display the Font dialog box for the label. Set the font size to 24 points (a point is ¹/72 inch and 24 points is about twice the height of a word processor's character on the screen) and set the Bold property.
As Figure 3.10 shows, the label's text is now large enough to read, but the text is not well centered within the label. Change the label's Alignment property to 2-Center, and the text centers just fine.

8. Change the label's BorderStyle property to 1-FixedSingle. This property adds a single-line 3D border around the label. You'll see that the label's Height property is too large, so click the label to display its sizing handles and drag the top edge downward to center the text within the label.

Figure 3.9. A label is this form's first control.

Figure 3.10. The label needs to be centered.

9. Add a command button, but to do so, double-click the command button tool on the Toolbox window. The command button appears in the middle of the form and you can leave it where it is.

10. Change the command button's Name property to cmdExit. Change the command button's Caption property to E&xit. Watch the command button as you type the Caption property text. The command button's caption becomes the text you type with one exception: The x is underlined. When you precede a Caption property's letter with an ampersand (&), Visual Basic uses that letter for the control's hotkey. Users of your application will be able to select the command button not only by clicking with the mouse, but also by pressing Alt+X on the keyboard.

11. The command button will be used to exit the program. When the user clicks the command button, your application should end. What happens anytime a user clicks a command button? A Click event occurs. Therefore, to respond to this event, you must write an event procedure for the command button. Visual Basic helps. Double-click the form's command button and Visual Basic instantly opens the Code window and displays the following wrapper lines for the command button's Click event procedure:

Private Sub cmdExit_Click()



End Sub