Step 4. Create the Property Page

At this point the filter supports everything that it needs for a property page. The next step is implementing the property page itself. Start by deriving a new class from CBasePropertyPage. The following example shows part of the declaration, including some private member variables that will be used later in the example:

class CGrayProp : public CBasePropertyPage
{
private:
    ISaturation *m_pGray;    // Pointer to the filter's custom interface.
    long        m_lVal       // Store the old value, so we can revert.
    long        m_lNewVal;   // New value.
public:
    /* ... */
};

Next, create a dialog resource in the resource editor, along with a string resource for the dialog title. The string will appear in the tab for the property page. The two resource IDs are arguments to the CBasePropertyPage constructor:

CGrayProp::CGrayProp(IUnknown *pUnk) : 
  CBasePropertyPage(NAME("GrayProp"), pUnk, IDD_PROPPAGE, IDS_PROPPAGE_TITLE),
  m_pGray(0)
{ }

The following illustration shows the dialog resource for the example property page.

Now you are ready to implement the property page. Here are the methods in CBasePropertyPage to override:

• OnConnect is called when the client creates the property page. It sets the IUnknown pointer to the filter.
• OnActivate is called when the dialog is created.
• OnReceiveMessage is called when the dialog receives a window message.
• OnApplyChanges is called when the user commits the property changes by clicking the OK or Apply button.
• OnDisconnect is called when the user dismisses the property sheet.

The remainder of this tutorial describes each of these methods.