A Comprehensive Guide to Developing ActiveX Controls Using Visual C++334

ActiveX controls are reusable software components that can be embedded into web pages or other applications. They provide a convenient way to add functionality to your projects without having to write all the code yourself. In this tutorial, we will walk you through the steps of creating an ActiveX control using Visual C++. We will cover everything from creating the project to registering and using the control.## Creating the Project
1. Open Visual C++ and create a new project.
2. Select the "ATL Project Wizard" from the list of project templates.
3. Enter a name for your project and click "Finish".
## Adding the Control Class
1. In the Solution Explorer, right-click on the project name and select "Add" > "New Item".
2. Select the "Class" template and click "Add".
3. Enter a name for your control class and click "Add".
## Implementing the Control Interface
1. In the header file for your control class, add the following code:
```cpp
#include
#include
class ATL_NO_VTABLE COleSampleControl :
public CComControl,
public IDispImpl
{
public:
COleSampleControl()
{
// Initialize your control here
}
BEGIN_COM_MAP(COleSampleControl)
COM_INTERFACE_ENTRY(IOleSampleControl)
END_COM_MAP()
// Implement your control's methods here
};
```
This code creates a COM object that implements the IOleSampleControl interface. The IDispImpl macro generates the necessary code to support the IDispatch interface, which is used for scripting and automation.
## Adding Properties and Methods
You can add properties and methods to your control by adding members to the COleSampleControl class. For example, to add a property called "Text", you would add the following code:
```cpp
public:
CString m_text;
STDMETHOD(get_Text)(BSTR* pVal)
{
*pVal = ();
return S_OK;
}
STDMETHOD(put_Text)(BSTR newVal)
{
m_text = newVal;
return S_OK;
}
```
## Registering the Control
Once you have implemented your control, you need to register it so that it can be used by other applications. To do this, open the registry editor () and navigate to the following key:
```
HKEY_CLASSES_ROOT\CLSID\{YOUR_CONTROL_CLSID}
```
Replace {YOUR_CONTROL_CLSID} with the CLSID of your control. If you do not know the CLSID, you can use the OleView tool to find it.
Under the CLSID key, create a new key called "InprocServer32". Set the default value of this key to the path of the DLL that contains your control.
## Using the Control
To use your control in another application, you need to add a reference to the control's type library. You can do this by opening the "Project" menu and selecting "References". In the "Add References" dialog box, select the "COM" tab and browse to the type library for your control.
Once you have added a reference to the type library, you can create an instance of your control using the following code:
```cpp
IOleSampleControlPtr control;
(CLSID_YourControl);
```
You can then set the properties and call the methods of your control as needed.
## Conclusion
In this tutorial, we have shown you how to create an ActiveX control using Visual C++. We covered everything from creating the project to registering and using the control. We encourage you to experiment with the code and create your own custom controls.