CURLLinkButton - Customizable Hyperlink Control

Introduction

The CURLLinkButton class extends the functionality of CButton by providing support for URL links. It displays the URL link and invokes the shell when clicked. It can be used in your project to link to any URL such as your website, an application, a folder or your email. You also can use it like other buttons to show a messagebox, dialogbox or anything you like.

This is a hyperlink control which really act like the ones used in Internet Explorer^® with following features:

1. Can be plugged into any dialog, form or view
2. Link to the any URL and email
3. Contains a built-in ToolTip
4. Customize the displayed text, URL-Prefix, URL, Tooltip text.
5. Customize the colors of Hyperlink (regular, hover, visited) and Tooltip (text color, background color)
6. Use a custom cursor or use the standard Hand cursor
7. Resize a URL link button to the size of the button's caption
8. Can be focused, navigated and activated using the keyboard
9. Send a message to parent when clicked
10. Easy to understand, easy to use

Thanks to Niek Albers for _TrackMouseEvent(). Thanks to Paul DiLascia for default hand cursor from WinHlp32.

Using the code

The code is quite short, reuseable and easy to understand. For using this control in your project, you need to do :

1. Add URLLinkButton.h and URLLinkButton.cpp to your project.
2. Include URLLinkButton.h in the header file where the controls are defined
3. Add some buttons to the dialog or form. Add a member variable for each button you want to customize as a hyperlink control. Replace the type of those variables from CButton to CURLLinkButton.
4. Use following operators to customize the control:

//Resize a URL link button to the size of the button's caption
void SizeToContent();
//Customize the colors of Hyperlink
void SetLinkColor(COLORREF clrRegular, COLORREF clrHover, COLORREF clrVisited);
//Customize the colors of the Tooltip
void SetToolTipColor(COLORREF clrTextColor, COLORREF clrBkColor);
//Customize the tooltip text. Use default tooltip if sTip is empty
void SetToolTipText(CString sTip=_T(""));
// Set URL. By default, window text will be used
void SetURL (LPCTSTR lpszURL);
//Set URL prefix. For example "mailto:"
void SetURLPrefix (LPCTSTR lpszPrefix); 

If you have a cursor resource in you project, you can customize the cursor or you can use default hand cursor

#if(WINVER >= 0x0500)
//Load system hand cursor
    m_hCursorHand = AfxGetApp()->LoadCursor (IDC_HAND);
#else
// Use a custom Hand cursor
    // Must add a cursor resourse in the project with ID: IDC_CURSOR_HAND
    //m_hCursorHand = AfxGetApp()->LoadCursor (IDC_CURSOR_HAND);

// If you haven't the cursor resourse in your project
    // load default hand cursor from WinHlp32 module with ID=106
    TCHAR szWindowsDir[MAX_PATH];
GetWindowsDirectory(szWindowsDir ,MAX_PATH);
strcat(szWindowsDir,"\\Winhlp32.exe");
HMODULE hModule = LoadLibrary(szWindowsDir);
if (hModule)
m_hCursorHand = ::LoadCursor(hModule, MAKEINTRESOURCE(106));
#endif 

When the link button is clicked, ShellExecute is called to open the URL. If this fails, it sends a registered message to the parent window.

const UINT WM_LINK_CLICKED = ::RegisterWindowMessage (_T ("WM_LINK_CLICKED"));

You can create a message handler of the parent window to do anything you want when the hyperlink is clicked. For example:

afx_msg LRESULT OnLinkCliked(WPARAM wParam, LPARAM lParam);
ON_REGISTERED_MESSAGE(WM_LINK_CLICKED, OnLinkCliked)
LRESULT CURLLinkDlg::OnLinkCliked(WPARAM wParam, LPARAM lParam)
{
UINT nLinkID = (UINT)wParam;
switch(nLinkID)
{
case IDOK:
OnOK();
break;
case IDC_SHOW_MESSAGE:
MessageBox(_T("Hope you find this code useful!"));
break;
}
return 0;
}

History

• July 18, 2004:
  Initial public release to The Code Project.
  
• March 02, 2005:
  Fix memory leak.
  Fix infinite loop problem when invoke the return key on the link to show a dialogbox
  You now don't have to check the option “Owner draw” of the link button