ch15.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！

	<DD><B>5. </B>Double-click the button and you will find that nothing happens. An
	ActiveX control doesn't have the capability to automatically create an event handler
	when you double-click the button like a VCL component does. Instead, switch to the
	Events page and double-click the Value column next to the OnClick event. An event
	handler is generated. Type this line of code:
	<P>
</DL>



<BLOCKQUOTE>
	<PRE>MessageDlg(`Hey, it works!', mtInformation, [mbOK], 0);</PRE>

</BLOCKQUOTE>

<PRE></PRE>

<DL>
	<DT></DT>
	<DD><B>6. </B>Run the program and test the button to ensure that it works. When you
	have verified that the button works, close the program.
	<P>
	<DT></DT>
	<DD><B>7. </B>Bring up the form and right-click on the button. Choose About from
	the context menu. The control's About box is displayed. The About box is not customized
	in any way, but you can go back and do that later if you want (provided you saved
	the file earlier).
	<P>
</DL>



<BLOCKQUOTE>
	<P>
<HR>
<strong>NOTE:</strong> The idea behind one-step ActiveX is to take a working VCL component
	and create an ActiveX control from that component. Most of the time, you won't have
	to modify the ActiveX code in any way. However, you certainly can modify the ActiveX
	code after it has been generated by Delphi if you so desire. Be aware, though, that
	if you regenerate the ActiveX code from your original VCL component, all changes
	made to the ActiveX source will be lost.<BR>
	<strong>NOTE:</strong> You can create ActiveX controls only from windowed VCL controls (controls
	derived from TWinControl or one of its descendents). The list of VCL controls from
	which you can build an ActiveX control contains all installed components that specifically
	meet this criteria. 
<HR>


</BLOCKQUOTE>

<P><B>Unregister the ActiveX Control</B></P>
<P>After experimenting with your new ActiveX control, you should unregister it so
that it doesn't occupy space in the Registry. To unregister the ActiveX control,
do this:</P>

<DL>
	<DT></DT>
	<DD><B>1. </B>Choose Component|Import ActiveX Control from the main menu.
	<P>
	<DT></DT>
	<DD><B>2. </B>Select the ActiveX in the list of installed ActiveX controls and click
	the Remove button.
	<P>
	<DT></DT>
	<DD><B>3. </B>Click Yes on the confirmation dialog box to have Delphi unregister
	the ActiveX.
	<P>
</DL>

<P>Alternatively, you can load the ActiveX project (if you previously saved it) and
choose Run|Unregister ActiveX Server from the main menu.</P>


<BLOCKQUOTE>
	<P>
<HR>
<strong>NOTE:</strong> If all else fails, you can always locate the ActiveX control in the
	Registry and delete the key for that control. Use the Registry Editor's find function
	to find the key (search for the control's name or its GUID). Naturally, you want
	to be careful when editing the Registry manually. 
<HR>


</BLOCKQUOTE>

<H4>Creating ActiveForms</H4>
<P>Creating an ActiveForm is almost as easy as creating an ActiveX from an existing
VCL component. Naturally, you can create a complex ActiveX containing many components
on a single form. Contrary to what its name implies, however, an ActiveForm can be
used to create a simple ActiveX control from scratch (a colored button, for example).
In other words, ActiveForms are not only for creating fancy forms with dozens of
gadgets. They are for creating single-use ActiveX controls as well.</P>
<P>In this section, you will create an ActiveForm. The ActiveForm will have two edit
controls, a label and a button. The button will take the contents of the two edit
controls, multiply them together, and display the result in the label. Yes, I know
it doesn't require a lot of imagination to stick with the &quot;multiply two numbers&quot;
idea, but my goal is to show you how to create an ActiveForm with the minimum amount
of code. Keeping the code to a minimum allows you to focus on the ActiveForm creation
process without getting bogged down in code.</P>
<P><B>Create the ActiveForm</B></P>
<P>Creating an ActiveForm is so easy it's amazing. Follow these steps:</P>

<DL>
	<DT></DT>
	<DD><B>1. </B>Close all projects and then choose File|New from the main menu. The
	Object Repository is displayed.
	<P>
	<DT></DT>
	<DD><B>2. </B>Double-click the ActiveForm icon. The ActiveForm Wizard is displayed.
	This dialog box is identical to the ActiveX Control Wizard except for the fact that
	the VCL Class Name field is grayed (it doesn't apply here).
	<P>
	<DT></DT>
	<DD><B>3. </B>Enter MyFormX in the New ActiveX Name field.
	<P>
	<DT></DT>
	<DD><B>4. </B>Change the Implementation Unit field to read MyFormImpl.pas.
	<P>
	<DT></DT>
	<DD><B>5. </B>Change the Project Name field to MyFormProj.dpr.
	<P>
	<DT></DT>
	<DD><B>6. </B>Leave the Thread Model set to Apartment. Check the Include Version
	Information check box.
	<P>
	<DT></DT>
	<DD><B>7. </B>Click the OK button to continue.
	<P>
</DL>

<P>Delphi creates the required units and displays a form.</P>
<P><B>Create the Form</B></P>
<P>An ActiveForm form is just a regular form at this stage. You can add controls
to the form, add code, and respond to events just like you do for a form that belongs
to an application. The one difference is that the title bar on an ActiveForm does
not appear on the control itself. It's just there at design time.</P>
<P>In this step, you will add components and code to make the ActiveForm functional.
As you work through the steps, it might help to refer to Figure 15.8 later in the
chapter, which shows the completed form. I'm going to give you the primary components
in the following steps and let you finish the rest on your own. Perform these steps:</P>

<DL>
	<DT></DT>
	<DD><B>1. </B>Size the form to approximately 175 (width) by 275 (height).
	<P>
	<DT></DT>
	<DD><B>2. </B>Add an Edit component near the top-center of the form (see Figure 15.8).
	Change its Name property to Num1Edit, its Text property to 0, and its Width to 50
	or so (the exact width is not important). Change the AxBorderStyle property to afbRaised.
	<P>
	<DT></DT>
	<DD><B>3. </B>Click on the Edit component and copy it to the Clipboard; paste a new
	component from the Clipboard. Place the new component below the first. Change its
	Name property to Num2Edit.
	<P>
	<DT></DT>
	<DD><B>4. </B>Place a Label component below the two edit controls. This label will
	display the results. Change the label's Name property to ResultLbl and its Caption
	property to 0.
	<P>
	<DT></DT>
	<DD><B>5. </B>Place a Button component on the form to the right of the Edit components.
	Change its Name to GoButton and its Caption to Go!.
	<P>
	<DT></DT>
	<DD><B>6. </B>Double-click the button and make the OnClick event handler look like
	this:
	<P>
</DL>



<BLOCKQUOTE>
	<PRE>procedure TMyFormX.GoButtonClick(Sender: TObject);
begin
  try
    ResultLbl.Caption := IntToStr(
      StrToInt(Num1Edit.Text) * StrToInt(Num2Edit.Text));
  except
    on EConvertError do
      MessageDlg(`Oops! You entered an invalid value.',
        mtError, [mbOK], 0);
  end;
end;</PRE>

</BLOCKQUOTE>

<PRE></PRE>

<DL>
	<DT></DT>
	<DD>This code simply extracts the values of the two edit controls, multiplies them
	together, and displays the result in the ResultLbl label. The exception handling
	code displays a message box if the user enters invalid values. An EConverError exception
	will be raised if the conversion from text to integer fails (if one of the edit controls
	contains text, for example).
	<P>
	<DT></DT>
	<DD><B>7. </B>Add additional labels to match Figure 15.8.
	<P>
	<DT></DT>
	<DD><B>8. </B>Choose View|Type Library from the main menu. In the Information page,
	change the Help String field to My Test ActiveForm Library. This is the text that
	will be displayed in the Import ActiveX dialog box when you install the ActiveForm.
	<P>
	<DT></DT>
	<DD><B>9. </B>Save the project. Accept the default filenames. (You specified them
	in the ActiveForm Wizard.) Figure 15.8 shows the completed form.
	<P>
</DL>

<P><A HREF="javascript:popUp('28671508.gif')"><B>FIGURE 15.8.</B></A><B> </B><I>The
finished ActiveForm.</I></P>

<P><B>Build, Register, and Import the ActiveForm</B></P>
<P>Now you can build, register, and import the ActiveForm. When built, the ActiveForm
is like any other ActiveX control. Because you've done this several times now, I'm
not going to go over every step. Follow these steps:</P>

<DL>
	<DT></DT>
	<DD><B>1. </B>Choose Project|Build MyFormProj from the main menu.
	<P>
	<DT></DT>
	<DD><B>2. </B>When the project is built, choose Run|Register ActiveX Server from
	the main menu.
	<P>
	<DT></DT>
	<DD><B>3. </B>Choose Component|Import ActiveX Control from the main menu. Install
	My Test ActiveForm Library (Version 1) into the DCLUSR40 package. Install to the
	ActiveX page or any other page you choose.
	<P>
</DL>

<P>The ActiveForm is now installed as an ActiveX control.</P>
<P><B>Try the ActiveForm</B></P>
<P>Now it's time to take the ActiveForm for a test drive. This will be fairly simple:</P>

<DL>
	<DT></DT>
	<DD><B>1. </B>Create a new application.
	<P>
	<DT></DT>
	<DD><B>2. </B>Click the ActiveX tab on the Component palette and choose MyFormX button
	(the one with the default Delphi icon).
	<P>
	<DT></DT>
	<DD><B>3. </B>Place a MyFormX control on your form.
	<P>
	<DT></DT>
	<DD><B>4. </B>Run the program and test out the ActiveX.
	<P>
</DL>

<P>That's all there is to it. With Delphi, great-looking ActiveX controls are a breeze
to create! There simply is no better development environment for creating ActiveX
controls than Delphi, bar none.</P>
<P>
<H3><A NAME="Heading10"></A>Changing the ActiveX Palette Bitmap</H3>
<P>Ultimately you will want to change the bitmap of the ActiveX from the default
that Delphi provides to one of your own design. Changing the bitmap requires following
these steps:</P>

<DL>
	<DT></DT>
	<DD><B>1. </B>Create a binary resource file (.RES) with Image Editor.
	<P>
	<DT></DT>
	<DD><B>2. </B>Create a 24&#165;24 bitmap. Give the bitmap a numeric name (2 for example).
	<P>
	<DT></DT>
	<DD><B>3. </B>Link the resource file to the ActiveX project with the $R compiler
	directive. (Linking resources was discussed on Day 8, &quot;Creating Applications
	in Delphi&quot; and is discussed further on Day 20, &quot;Creating Components.&quot;)
	<P>
	<DT></DT>
	<DD><B>4. </B>Modify the ActiveX class factory creation routine in the implementation
	unit (the ActiveForm's .PAS file). A typical class factory creation routine looks
	like this (it's in the initialization section at the bottom of the unit):
	<P>
</DL>



<BLOCKQUOTE>
	<PRE>TActiveFormFactory.Create(
    ComServer,
    TActiveFormControl,
    TMyFormX,
    Class_MyFormX,
    1,                    { Change this number. }
    `',
    OLEMISC_SIMPLEFRAME or OLEMISC_ACTSLIKELABEL,
    tmApartment);</PRE>

</BLOCKQUOTE>

<PRE></PRE>

<DL>
	<DT></DT>
	<DD>Notice the line I have marked with a comment. This parameter of TActiveFormFactory.Create
	is the resource number of the bitmap you want displayed on the Component palette.
	If you saved the new bitmap with a name of 2, you would replace the 1 in this code
	snippet with a 2.
	<P>
	<DT></DT>
	<DD><B>5. </B>Rebuild, reregister, import, and install the ActiveForm again. The
	new bitmap should now show up in the Component palette.
	<P>
</DL>

<P>Alternatively, you can modify the ActiveForm project's .RES file and change the
bitmap named 1 to look like you want.</P>
<P>
<H2><A NAME="Heading11"></A>Web Deploying ActiveX Controls and ActiveForms</H2>
<P>One of the great features of ActiveForms is that you can use them on a Web page.
In order to use an ActiveForm on a Web page, you must use the Web Deploy option.
Using Web Deploy requires a Web server, so I can't effectively walk you through the
Web deployment process. I can, however, give you a little insight into the process.
When you choose Web Deploy, Delphi performs two tasks:</P>

<UL>
	<LI>Builds the ActiveX control and copies the file to the Web Deploy target directory
	<P>
	<LI>Creates an HTML file that contains the code needed to load the ActiveX control
</UL>

<P>The locations of these files is determined by the Web deployment options. Let's
look at that next.</P>
<P>
<H3><A NAME="Heading12"></A>Web Deployment Options</H3>
<P>Before you can use Web Deploy, you must set the Web deployment options. To set
the Web deployment options, choose Project|Web Deployment Options from the main menu.
The Web Deployment Options dialog box is displayed, as shown in Figure 15.9.</P>
<P><A HREF="javascript:popUp('28671509.gif')"><B>Figure 15.9.</B></A><B> </B><I>The
Web Deployment Options dialog box.</I></P>

<P>At the bottom of the Web Deployment Options dialog box is a check box labeled
Default. Check this box if you want the settings you have specified to be the new
defaults fo