ch08.htm

delphi自学的好教材！特别适合刚刚起步学习delphi的人员！同样对使用者具有参考价值！

</BLOCKQUOTE>

<P>An object can be moved from one page to another by simply dragging the object
from the Objects list box to the Pages list box. Drop the object on the page on which
you want the object to be located, and the object is moved.</P>
<P>
<H4>Managing Pages</H4>
<P>The previous section deals with editing, deleting, and moving individual objects.
You can also add, delete, or remove Object Repository pages through the Object Repository
configuration dialog box. Before you can delete a page, you must first delete all
the objects on the page. After a page is empty, you can remove the page by clicking
on the page name in the Pages list box and then clicking the Delete Page button.
After checking to be sure the page is empty, Delphi deletes the page from the Object
Repository.</P>
<P>A new page can be added by clicking the Add Page button. A dialog box pops up
asking for the name of the new page. Just supply a new page name and when you click
OK, the new page appears in the Pages list box. Renaming a page works essentially
the same way. When you select a page and click the Rename Page button, a dialog box
appears prompting you for the new page name.</P>
<P>The order in which the pages appear in the Object Repository can be changed. To
change a page's position in the page order, click the page to highlight it and then
click the up or down arrow button underneath the Pages list box to move the page
up or down in the list. You can also drag a page to its new location if you want.</P>
<P>
<H4>Setting Default Forms and Projects</H4>
<P>The Object Repository configuration dialog box enables you to set three default
objects:</P>

<UL>
	<LI>The default form that is used when you choose File | New Form from the main menu.
	<P>
	<LI>The default form that is used as the main form when you choose File | New Application
	from the main menu.<BR>
	<BR>
	
	<LI>The default project that is used when you choose File | New Application from
	the main menu.
</UL>

<P>You will notice that, depending on the object you select, one or two check boxes
appear beneath the Objects list box. If you select a form, the New Form and Main
Form check boxes appear. If you select a project, the New Project check box appears.</P>
<P>
<P>Making a form or project the default is easy. Let's say you create a main form
that you want to be the default main form when a new application is created. Select
the form from the Objects list box and click the Main Form check box at the bottom
of the screen. When you click OK, that form will now be the default. Similarly, if
you have a project that you want to be the default project, first locate it in the
Object Repository configuration dialog box, click on it, and then check the New Project
check box. From that point on, when you choose File | New Application from the main
menu, the project you set as the default will appear.</P>
<PRE></PRE>


<BLOCKQUOTE>
	<P>
<HR>
<strong>NOTE:</strong> If you aren't careful, you can accidentally select a form as the
	default form for a new application. If this happens, be sure you check each form
	in the Object Repository configuration dialog box. One form will have the Main Form
	check box checked. Clear the check box and all will be back to normal. This also
	applies to the default project. Check the Projects page for any items that have the
	New Project check box checked. 
<HR>


</BLOCKQUOTE>

<P>
<H2><A NAME="Heading8"></A>Building Forms and Applications with the Wizards</H2>
<P>Delphi has two built-in wizards designed to guide you through the application
creation process. The Dialog Wizard aids you in creating dialog boxes, and the Application
Wizard helps you create the basic layout of an application. These wizards are discussed
in the following sections.</P>
<P>
<H3><A NAME="Heading9"></A>Using the Dialog Wizard</H3>
<P>Truthfully, there isn't very much for a dialog box wizard to do because dialog
boxes of any real value will need to be customized with the Form Designer. The Dialog
Wizard is started from the Object Repository. First, choose File | New from the main
menu to display the Object Repository. Next, switch to the Dialogs page and then
double-click the Dialog Wizard icon. The Dialog Wizard is displayed as shown in Figure
8.5.</P>
<P><A HREF="javascript:popUp('28670805.gif')"><B>FIGURE 8.5.</B></A><B> </B><I>The
Dialog Wizard.</I></P>
<P>You can choose to create a single-page dialog box or a tabbed (multipage) dialog
box. The icon on the left side of the dialog box shows you what the dialog box looks
like at each step. If you choose to create a single-page dialog box, when you click
the Next button, you will see the next page of the Dialog Wizard (see Figure 8.6).</P>
<P><A HREF="javascript:popUp('28670806.gif')"><B>FIGURE 8.6.</B></A><B> </B><I>The
second page of the Dialog Wizard.</I></P>
<P>This page enables you to choose whether you want buttons on the dialog box and,
if so, whether you want them on the right side or the bottom of the dialog box. This
is the last page of the Dialog Wizard when creating a single-page dialog box. After
choosing the button layout you want, click the Finish button to have Delphi create
the dialog box for you.</P>
<P>The new dialog box is displayed on the Form Designer complete with the features
you chose through the wizard. It also has its BorderStyle property set to bsDialog,
which is customary for forms used as dialog boxes. After the Dialog Wizard has created
the basic dialog box, you can go to work with the Form Designer to add functionality
to the dialog box.</P>
<P>If you choose to create a tabbed dialog box, the second page of the dialog box
looks like the one shown in Figure 8.7. (Figure 8.7 shows the dialog box after page
names have been added.)</P>
<P>This page has a multiline edit control in which you can enter the names of the
individual tabs you want to see on the dialog box. Enter the text for each tab on
a separate line, as illustrated in Figure 8.7. When you click the Next button, you
will see the last page of the Dialog Wizard as you saw in Figure 8.6. Choose the
location of the buttons, if any, and click the Finish button to have Delphi create
the tabbed dialog box.</P>
<P><A HREF="javascript:popUp('28670807.gif')"><B>FIGURE 8.7.</B></A><B> </B><I>The
Dialog Wizard creating a tabbed dialog box.</I></P>


<BLOCKQUOTE>
	<P>
<HR>
<BR>
	<strong>NOTE:</strong> The Dialog Wizard is most useful when creating tabbed dialog boxes.
	When creating single-page dialog boxes, it is easier to choose one of the pre-defined
	dialog boxes from the Object Repository rather than going through the Dialog Wizard.
	
<HR>


</BLOCKQUOTE>

<H3></H3>
<H3><A NAME="Heading10"></A>Creating Applications with the Application Wizard</H3>
<P>The Application Wizard is a useful tool that can help you quickly set up the shell
of an application. To create a new application using the Application Wizard, choose
File | New from the main menu. When the Object Repository appears, click the Projects
tab and then double-click the Application Wizard icon.</P>


<BLOCKQUOTE>
	<P>
<HR>
<strong>NOTE:</strong> The New Application item on the main menu creates a new application
	based on the current default project setting. It doesn't start the Application Wizard
	as you might expect. 
<HR>


</BLOCKQUOTE>

<P>Let's walk through the Application Wizard one page at a time.</P>
<P>
<H4>Page One: Selecting the Menus</H4>
<P>When you start the Application Wizard, the first page is displayed as shown in
Figure 8.8.</P>
<P>This page enables you to select the items you want on your application's main
menu. You can choose to add a File menu, an Edit menu, a Window menu, and a Help
menu. Place a check in the box for each menu item you want to appear on your menu
bar.</P>


<BLOCKQUOTE>
	<P>
<HR>
<strong>NOTE:</strong> The Window menu is usually reserved for MDI applications. You probably
	won't put a Window menu on your SDI application's menu bar unless you have a specialty
	application that requires it. 
<HR>


</BLOCKQUOTE>

<P><A HREF="javascript:popUp('28670808.gif')"><B>FIGURE 8.8.</B></A><B> </B><I>Page
one of the Application Wizard.</I></P>


<BLOCKQUOTE>
	<P>
<HR>
<BR>
	<strong>NOTE:</strong> The menus added by the Application Wizard are a reasonable representation
	of the menu items that are most commonly used in Windows applications. Remember that
	the Application Wizard is intended to give you a head start in creating your application.
	It is up to you to take the basic structure and modify it to make a working application.
	
<HR>


</BLOCKQUOTE>

<P>After you have chosen the menus you want for your application, click the Next
button to move to the next page.</P>
<P>
<H4>Page Two: Setting the File Dialog Filters</H4>
<P>If you chose to add a File menu to your application, the next page displayed will
look like the one shown in Figure 8.9.</P>
<P><A HREF="javascript:popUp('28670809.gif')"><B>FIGURE 8.9.</B></A> <I>Setting filters
for the file dialog boxes.</I></P>
<P>This page enables you to set the filters that your application's File Open and
File Save dialog boxes will use. (Figure 8.9 shows the dialog box after the filters
have been added.) Click the Add button to add a new filter. A dialog box is displayed
asking for the description and the filter. Enter the filters exactly as you do when
setting the Filter property for the common file dialog box components. Enter the
textual description and then the actual file mask (*.bmp, for example). The Edit,
Delete, Up, and Down buttons can be used as necessary to change, delete, or move
the filter in the list.</P>


<BLOCKQUOTE>
	<P>
<HR>
<strong>NOTE:</strong> Pages two and three will be displayed only if you previously selected
	menus on page one of the Application Wizard. More specifically, page two will be
	displayed only if you selected a File menu on page one. 
<HR>


</BLOCKQUOTE>

<P>
<H4>Page Three: Setting Up the Speedbar</H4>
<P>Page three of the Application Wizard aids you in setting up a speedbar (also called
a toolbar) for your application. This is possibly the most useful feature of the
Application Wizard (not that the other features aren't useful). You can quickly lay
out your speedbar through this page. Figure 8.10 shows the third page of the Application
Wizard after a speedbar has been created.</P>
<P><A HREF="javascript:popUp('28670810.gif')"><B>FIGURE 8.10.</B></A><B> </B><I>Setting
up the speedbar.</I></P>
<P>The list box on the left side of the page, labeled Menus, shows the four menus
for which you can add buttons. When you choose one of the menus, the available buttons
for that menu are displayed in the list box to the right of the Menus list box (labeled
Available Commands). To add a speedbar button, click the button in the Available
Commands list box and then click the Insert button. The button will be added to the
sample speedbar at the top of the page.</P>
<P>The Space button can be used to add a separator to the speedbar. Adding separators
visually distinguishes groups of buttons. Continue to add buttons and spaces as needed
until the speedbar is complete. If you decide to remove a button, just click it in
the sample speedbar and then click the Remove button.</P>


<BLOCKQUOTE>
	<P>
<HR>
<strong>NOTE:</strong> If you elected not to add a particular menu to your application,
	no buttons will be shown for that menu group. For example, if you did not add a Window
	menu, the Available Commands list box will be empty when you click on the Window
	item in the Menus list box. 
<HR>
</P>
	<P>
<HR>
<BR>
	<strong>TIP:</strong> Some specialty applications have a speedbar but don't have a menu.
	To create a speedbar with the Application Wizard, you must first have created a menu.
	To work around this, tell the Application Wizard that you want a menu and then build
	the speedbar. After the application has been generated, you can delete the MainMenu
	component from the application to remove the menu. 
<HR>


</BLOCKQUOTE>

<H4><BR>
Page Four: Setting the Final Options</H4>
<P>The fourth and last page of the Application Wizard enables you to set the program
name, the path where the project should be stored on disk, and a few final options.
Figure 8.11 shows the last page of the Application Wizard.</P>
<P><A HREF="javascript:popUp('28670811.gif')"><B>FIGURE 8.11.</B></A><B> </B><I>The
final Application Wizard settings.</I></P>
<P>The first field on this page is where you specify the name of the application.
This is not the name as it appears on the Project Options dialog box, but the filename
that Delphi will use to save the project. You still need to set the application name
in the Project Options dialog box. The second field is used to specify the directory
in which the project should be saved. If you don't know the exact path, click the
Browse button to the right of this field and choose the path from the Select Directory
dialog box.</P>


<BLOCKQUOTE>
	<P>
<HR>
<STRONG>NOTE:</STRONG> You can use the Select Directory dialog box to create a directory
	as well as to select a directory. Click the Browse button to display the Select Directory
	dialog box. Enter the path for the directory you want to create and then click OK
	or press Enter. Delphi will prompt you to create the new directory if the directory
	you entered doesn't exist. 
<HR>


</BLOCKQUOTE>

<P>The bottom half of the final page gives you three additional options. If you are
creating an MDI application, click the check box marked Create MDI Application. (MDI
applications were discussed on Day 4, &quot;The Delphi IDE Explored.&quot;) The remaining
two check boxes enable you to implement a status bar and hint text for your components.</P>
<P>When you are sure you have made all the choices for your new application, click
the Next button. Delphi creates the application based on the options you specified.
Delphi writes as much code as possible for the application. This doesn't amount to
a lot of code, but some of the basic code is already written for you. For example,
if you chose a File menu, the FileOpenClick handler has been written and looks like
this:</P>
<P>
<PRE>procedure TMainForm.FileOpen(Sender: TObject);
begin
  if OpenDialog.Execute then
  begin
    { Add code to open OpenDialog.FileName }
  end;
end;
</PRE>
<P>The code to execute the File Open dialog box is in place; you only have to write
the code that actually deals with the returned filename.</P>