The concept of Focus - VISUAL BASIC TUTORIAL

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Friday, December 3, 2010

The concept of Focus

The concept of focus is important in Visual Basic.  The object that is selected (such as a form, control, or menu bar selection) is said to have focus.  In order for Visual Basic to know what file to save, it is necessary to click the object to give it focus, making it the active object.  Likewise, to remove a file, the object must be given focus.  To remove a file, open the Project window, click the file to remove, and choose File, Remove and the name of the file to remove will also appear.  An alternative is to display the Project Explorer, click the file that you want to delete, and right-click to produce the shortcut menu shown in Figure 2.3.  We discuss the concept of focus at length later.  There are even unique events, such as Gotfocus and LostFocus, that deal with this issue.

Figure 2.3 Display the Project Explorer and right-click to reveal several file optiions, including a command for removing a file from a project.

Exercise 2.2  Using the Remove and Add Commands

This exercise assumes that you completed Exercise 2.1 and saved the form as F2-1.frm.

  1. Open a new Standard EXE project, and change the name of the project to Project2_2 (click Project, Project1 Properties).
  2. Choose Project, Remove Form1.Form1 must have the focus because it is the only object assigned to the project.
  3. Choose Project, Add File.  Navigate through Windows to the location where you saved F2-1.frm, and add this form to your Project (see Figure 2.4).

    Figure 2.4

    The Add File dialog box lists saved forms that can be added to a project.

  4. Open the Project Explorer Window, and give form F2-1.frm the focus.
  5. Choose File, Save File As (or click the right mouse button).  When the dialog box opens, navigate to the location where you want to save the file, and name it F2-2.frm.
  6. Open the Project Window again and observe what happens.  The name of the form has been changed and assigned to the new project.
  7. Choose File, Save Project As.  In this instance, you are not asked to name the form because it has already been named and saved.  Instead, you are asked only to name the project, which we named P2-2.vbp.

Other File Menu Commands

Besides the four Project menu commands and the two file commands found on the File menu, the latter also contains the Print and Print Setup commands and the Make Project1.Exe commands, as follows:

  • Print – Choose File, Print to display several options for printing information about a project (see Figure 2.5).  You can print the form image, code, or the form as text, and you can choose to print information for a module or for the entire project.
  • Print Setup – Choose File, Print Setup to launch the standard Windows Print Setup dialog box.
  • Make Project1.Exe – Choose File, Make Project.Exe to create an executable application.  Project modules are compiled into a single .EXE file.  This file is either a P-Code interpreted executable or a native code executable file.  (The two code formats are explained in “Interpreted P-Code,” and “Compiled Native Code,” later.)

Both types of executables require runtime files.  The Visual Basic Setup Wizard can help you determine which runtime file your application requires.

Figure 2.5 The Print-Project dialog box enables you to choose the parts of an application that you want to print.

Exercise 2.3  Using the Print Command

This exercise is designed to show you the type of information printed for a project.

  1. Open a new Standard EXE project.
  2. Choose File, Print.
  3. When the dialog box appears, click Current Project, Form Image, Code and Form as Text.
  4. Click OK.

What is the difference between the Form Image and the Form as Text choice!  Why is there no computer code?

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