MORE INFORMATION
The LicReqst sample is a dialog-based MFC application that
illustrates how to use the
IClassFactory2 interface to request an object's
License key. LicReqst displays the ProgID of each of the currently registered
ActiveX controls in a list box. When one of the displayed ProgID's is selected,
an instance of the corresponding control is created and then asked for it's
License key. If a valid key is returned, LicReqst displays the key and enables
the
Copy to Clipboard button that allows the License key to be copied to the
Clipboard. The License key can then easily be pasted into code that uses the
CWnd::CreateControl method to dynamically create an instance of the control.
LicReqst creates a textual version of the License key data in the
form of a declaration of an array of WCHAR when copying the key to the
Clipboard. This is done because the License key data could contain
non-printable characters. A human-readable version of the License key data is
also provided for reference and is included inside a Comment block in the final
string that is copied to the Clipboard.
For example, if an object
uses the string
Copyright (c) 1994 for its License key,
LicReqst would generate the following block of text that could be copied to and
pasted from the Clipboard:
/*
Copyright (c) 1994
*/
WCHAR pwchLicenseKey[] =
{
0x0043, 0x006F, 0x0070, 0x0079, 0x0072, 0x0069,
0x0067, 0x0068, 0x0074, 0x0020, 0x0028, 0x0063,
0x0029, 0x0020, 0x0031, 0x0039, 0x0039, 0x0034,
0x0020
};
You can use the previous block of text in code that creates an instance
of the Licensed object, and you can use the
pwchLicenseKey variable to specify
the object's License key.
For example, if MFC code is dynamically
creating an instance of a licensed ActiveX control using the
Create method of a
Visual C++ Component Gallery generated wrapper class, the
pwchLicenseKey
variable can be used in the
Create method call like this:
BSTR bstrLicense = ::SysAllocStringLen(pwchLicenseKey,
sizeof(pwchLicenseKey)/sizeof(WCHAR));
m_MyControl.Create(NULL, WS_VISIBLE, CRect(10,10,10,10), this,
2, NULL, FALSE, bstrLicense);
::SysFreeString(bstrLicense);
Note how a bstrLicense is created from the
pwchLicenseKey variable and how the bstrLicense is then used for the License key parameter in the
Create method call.
Note The code in this sample that generates the text copied to the Clipboard
makes the assumption that it is being executed on a little endian system (Intel
x86-class processors). Because of this, it will not work correctly on big
endian system. For these systems, it is still possible to use the Helper
function used internally by the sample to request the License key from an
object.
The sample uses a Helper function called
RequestLicenseKey
to get the License key from an object based on its ProgID. The source code for
the
RequestLicenseKey function is shown later in the "Sample code" section.
To find other locations of interest in the sample source code, use
the Find in Files feature of the Visual C++ Developer Studio to search for the
string named SAMPLE CODE. This string has been used to tag each of the modified
sections in the source code.
Note Running the LicReqst sample on a
licensed machine to obtain an object's License key, and then distributing that
key to allow applications to be developed on other non-licensed machines, may
be a violation of established copyrights. For more information, and to determine
if an object's License key can be legally redistributed, refer to the License
Agreement provided with the object or contact the creator of the object.
Sample code
// Compile options needed: none
///////////////////////////////////////////////////////////////////////
// SAMPLE CODE - Implementation of the RequestLicenseKey function
//
// The RequestLicenseKey function uses the IClassFactory2 interface
// to request a License key from an object specified by its ProgID.
//
// Parameters:
//
// [out] BSTR& bstrLicenseKey
// Upon return, this BSTR will contain either a valid
// License key or an error message. It is the caller's
// responsibility to call ::SysFreeString on this BSTR.
//
// [in] CString strProgID
// Specifies the ProgID of the object from which to request the
// License key.
//
//
// Return Value:
//
// A BOOL specifying success or failure. If TRUE is returned,
// the License key was retrieved successfully and the
// bstrLicenseKey parameter contains a valid License key. If
// FALSE is returned, the License key was not retrieved
// successfully and the bstrLicenseKey parameter contains a
// descriptive error string.
//
// Regardless of the return value, it is the responsibility of
// the caller to call ::SysFreeString on the returned bstrLicenseKey
// parameter.
//
BOOL RequestLicenseKey(BSTR& bstrLicenseKey, CString strProgID)
{
USES_CONVERSION;
LPCLASSFACTORY2 pClassFactory;
CLSID clsid;
BOOL bValidKeyReturned = FALSE;
// Get the CLSID of the specified ProgID.
if (SUCCEEDED(CLSIDFromProgID(T2OLE(strProgID), &clsid)))
{
// Create an instance of the object and query it for
// the IClassFactory2 interface.
if (SUCCEEDED(CoGetClassObject(clsid, CLSCTX_INPROC_SERVER, NULL,
IID_IClassFactory2, (LPVOID *)(&pClassFactory))))
{
LICINFO licinfo;
// Check to see if this object has a runtime License key.
if (SUCCEEDED(pClassFactory->GetLicInfo(&licinfo)))
{
if (licinfo.fRuntimeKeyAvail)
{
HRESULT hr;
// The object has a runtime License key, so request it.
hr = pClassFactory->RequestLicKey(0, &bstrLicenseKey);
if (SUCCEEDED(hr))
{
if(bstrLicenseKey == NULL)
bstrLicenseKey = ::SysAllocString(
L"<Object returned a NULL license key>");
else
// You have the license key.
bValidKeyReturned = TRUE;
}
else
// Requesting the License key failed.
switch(hr)
{
case E_NOTIMPL:
bstrLicenseKey = ::SysAllocString(
L"<The object's class factory does not support"
L" run-time license keys>");
break;
case E_UNEXPECTED:
bstrLicenseKey = ::SysAllocString(
L"<An unexpected error occurred when requesting the"
L" run-time license key>");
break;
case E_OUTOFMEMORY:
bstrLicenseKey = ::SysAllocString(
L"<The object's class factory was unable to allocate"
L" the license key>");
break;
case CLASS_E_NOTLICENSED:
bstrLicenseKey = ::SysAllocString(
L"<The object's class factory supports run-time"
L" licensing, but the current machine\r\nitself is"
L" not licensed. Thus, a run-time key is not"
L" available on this machine>");
break;
default:
bstrLicenseKey = ::SysAllocString(
L"<An unknown error occurred when requesting the"
L" license key>");
}
}
else
bstrLicenseKey = ::SysAllocString(
L"<The object has no runtime license key>");
}
else
bstrLicenseKey = ::SysAllocString(
L"<Unable to get the licensing capabilities of the object's"
L" class factory>");
// Make sure you release the reference to the class factory.
pClassFactory->Release();
}
else
bstrLicenseKey = ::SysAllocString(
L"<Unable to get the IClassFactory2 interface from the"
L" specified object>");
}
else
bstrLicenseKey = ::SysAllocString(
L"<Unable to get the CLSID of the specified object>");
// Return a BOOL specifying whether or not you were able to get a
// valid license key.
return bValidKeyReturned;
}