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Adding a Control (ATL Tutorial, Part 2)

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In this step, you add a control to your project, build it, and test it on a Web page.

Procedures

To add an object to an ATL project

  1. In Solution Explorer, right-click the Polygon project.

  2. Point to Add on the shortcut menu, and click New Item in the submenu.

    The Add New Item dialog box appears. The different object categories are listed in the tree structure on the left.

  3. Click the ATL folder.

  4. From the list of templates on the right, select ATL Control. Click Add. The ATL Control wizard will open, and you can configure the control.

  5. Type PolyCtl as the short name and note that the other fields are automatically completed. Don't click Finish yet, because you must make some more changes.

The ATL Control wizard's Names page contains the following fields:

Field Contents
Short name The name you entered for the control.
Class The C++ class name created to implement the control.
.h file The file created to contain the definition of the C++ class.
.cpp file The file created to contain the implementation of the C++ class.
CoClass The name of the component class for this control.
Interface The name of the interface on which the control will implement its custom methods and properties.
Type A description for the control.
ProgID The readable name that can be used to look up the CLSID of the control.

You'll find several additional settings must be changed in the ATL Control wizard.

To enable support for rich error information and connection points

  1. Click Options to open the Options page.

  2. Select the Connection points check box. This option creates support for an outgoing interface in the IDL file.

You can also add interfaces to extend the control's functionality.

To extend the control's functionality

  1. Click Interfaces to open the Interfaces page.

  2. Select IProvideClassInfo2 and click the Up arrow to move it to the Supported list.

  3. Select ISpecifyPropertyPages and click the Up arrow to move it to the Supported list.

You can also make the control insertable, which means it's embeddable into applications that support embedded objects, such as Excel or Word.

To make the control insertable

  1. Click Appearance to open the Appearance page.

  2. Select the Insertable check box.

The polygon displayed by the object will have a solid fill color, so you have to add a Fill Color stock property.

To add a Fill Color stock property and create the control

  1. Click Stock Properties to open the Stock Properties page.

  2. Under Not supported, scroll down the list of possible stock properties. Select Fill Color and click the Up arrow to move it to the Supported list.

  3. Choose Finish.

As the wizard creates the control, several code changes and file additions occur. The following files are created:

File Description
PolyCtl.h Contains most of the implementation of the C++ class CPolyCtl.
PolyCtl.cpp Contains the remaining parts of CPolyCtl.
PolyCtl.rgs A text file that contains the registry script used to register the control.
PolyCtl.htm A Web page containing a reference to the newly created control.

The wizard also makes the following code changes:

  • Adds an #include statement to the precompiled header files to include the ATL files necessary for supporting controls.

  • Changes Polygon.idl to include details of the new control.

  • Adds the new control to the object map in Polygon.cpp.

Now you can build the control to see it in action.

Building and Testing the Control

To build and test the control

  1. On the Build menu, click Build Polygon.

    Once the control finishes building, right-click PolyCtl.htm in Solution Explorer and select View in Browser. The HTML Web page containing the control is displayed. You should see a page with the title "ATL 8.0 test page for object PolyCtl", and your control, the text PolyCtl.

Note

If the control isn't visible, know that some browsers require settings adjustments to run ActiveX controls. Refer to the browser's documentation on how to enable ActiveX controls.

Note

When completing this tutorial, if you receive an error message that the DLL file can't be created, close the PolyCtl.htm file and the ActiveX Control Test container and build the solution again. If you still can't create the DLL, reboot the computer, or log off if you are using Terminal Services.

Next, you'll add a custom property to the control.

Back to Step 1 | On to Step 3

See also

Tutorial