Internet Explorer Skin Manager

• Download demo project (with bmp) - 267 Kb
• Download source - 7 Kb

Introduction

As you can see in the snapshot above, Internet Explorer (IE version 5 and above) lets you use a bitmap as a skin/wallpaper for the IE toolbar, just to make it a bit more interesting. This tiny utility allows you set/remove IE skin with a convenient dialog based application. In the process, we delve into Windows Registry programming using CRegKey class.

The utility is a simple dialog based application, with plain vanilla GUI as you can see above. The code can be easily divided into the handlers of the buttons shown above. Rest of the article will discuss the important steps with the relevant code snippets.

Choosing a bitmap

The OnChoose() handler for button "Choose..." opens a file open dialog with filter set as - Bitmap Files, as .bmp files are the only files allowed for IE skins. Other image formats such as JPEG and GIF are not supported for IE skin/wallpaper. This function gets the path of the file selected by the user and sets m_szFilePath to this value. It also displays the file path in the read only edit box. The code for OnChoose() is -

void CIESkinDlg :: OnChoose()
{
    //open a file dialog with only BMP files filter, 
    //other formats not allowed
    LPCTSTR lpszFilter = "Bitmap Files (*.bmp)|*.bmp||";

    CFileDialog dlgFile(TRUE,NULL,NULL,OFN_FILEMUSTEXIST|OFN_EXPLORER,
        lpszFilter,this);

    if(IDOK == dlgFile.DoModal())
    {
        m_szFilePath = dlgFile.GetPathName();
        
        //display file path in the edit box
        SetDlgItemText(IDC_EDIT,m_szFilePath);
    }
}

Set bitmap as a skin

To set selected bitmap file as a skin for Internet Explorer, you must specify path of the selected file as a value data for the registry value BackBitmap under the registry key -

HKEY_CURRENT_USER
   \Software
       \Microsoft
           \Internet Explorer
               \Toolbar

The registry modifications are done using the class CRegKey, which provides methods for manipulating values in the system registry. Note that, you need to include atlbase.h header file in your code to use CRegKey class.

The function SetIESkin() sets the bitmap as skin. This function in turn is invoked by the OnSet() handler of the "Set Skin" button. The function opens the required registry key, sets value of BackBitmap to m_szFilePath, which is the file selected by the user, and in the end closes the key. The code -

BOOL CIESkinDlg :: SetIESkin()
{
    LONG lResult = 0;
    CRegKey reg;
    //open the required registry key
    LPCTSTR lpszKey = "Software\\Microsoft\\Internet Explorer\\Toolbar";
    lResult = reg.Open(HKEY_CURRENT_USER,lpszKey);

    //check if opened successfully
    if(ERROR_SUCCESS != lResult)
    {
        return FALSE;
    }   
    //set the value
    lResult = reg.SetValue(m_szFilePath,"BackBitmap");
    if(ERROR_SUCCESS != lResult)
    {
        return FALSE;
    }
    //done, close and return success
    reg.Close();
    return TRUE;
} 

Let's look into some CRegKey functions now, the function CRegKey::Open opens the specified key and sets m_hKey to the handle of this key. The prototype is -

LONG Open( HKEY hKeyParent, LPCTSTR lpszKeyName, 
    REGSAM samDesired = KEY_ALL_ACCESS )

• hKeyParent - It is a handle to a currently open key or one of the predefined reserved handle values such as - HKEY_CURRENT_USER, HKEY_LOCAL_MACHINE etc.
• lpszKeyName - It specifies the name of a key to be opened. This name must be a sub-key of hKeyParent.
• samDesired - The security access for the key. Depending on this, reading or writing of the registry key is permitted. The default value is KEY_ALL_ACCESS. The other values include - KEY_WRITE, KEY_READ and KEY_QUERY_VALUE. If your application only requires to read the registry values, you would probably want KEY_QUERY_VALUE or KEY_READ access.

Another function used here is LONG SetValue( DWORD dwValue, LPCTSTR lpszValueName ), which stores data in the specified value field of an open registry key. If the value name does not exist under that particular sub-key, it is created for storing the data. This version of SetValue uses m_hKey as the open key.

The function LONG Close( ) closes the key, releasing the m_hKey member handle and sets it to NULL. When the key is closed, its registry data is written (flushed) to the hard disk. If your application must explicitly write registry data to the hard disk, you can call the RegFlushKey Win32 function.

All these functions return ERROR_SUCCESS if successful, or they return an error value otherwise. You can use the Win 32 FormatMessage function with the FORMAT_MESSAGE_FROM_SYSTEM flag to get a generic description of the error.

Removing the skin

To remove the skin from IE you need to delete the registry value BackBitmap, which was set earlier using the function SetIESkin(). This is done by the function RemoveIESkin(), which in turn is invoked by the OnRemove() handler of the "Remove Skin" button.

The RemoveIESkin() function opens the required key, deletes the BackBitmap value of the key from the system registry, and in the end closes the key. Successful deletion of this value will clear the IE toolbar. If the value to be deleted is not found, the function returns FALSE, indicating error. The code -

BOOL CIESkinDlg :: RemoveIESkin()
{
    LONG lResult = 0;
    CRegKey reg;
    //open the required registry key
    LPCTSTR lpszKey = "Software\\Microsoft\\Internet Explorer\\Toolbar";
    lResult = reg.Open(HKEY_CURRENT_USER,lpszKey);

    //check if opened successfully
    if(ERROR_SUCCESS != lResult)
    {
        return FALSE;
    }
    //delete the value "BackBitmap" from toolbar
    lResult = reg.DeleteValue("BackBitmap");

    //check if deleted successfully
    if(ERROR_SUCCESS != lResult)
    {
        return FALSE;   //perhaps value not found, if skin is not set
    }
    //done, return success
    reg.Close();
    return TRUE;
}

The function CRegKey::DeleteValue actually deletes value field of the key identified by m_hKey, which in turn is set by CRegKey::Open. The prototype of CRegKey::DeleteValue is -

LONG DeleteValue( LPCTSTR lpszValue )

The function accepts parameter lpszValue, which specifies the value field to be removed. If the value is deleted successfully, the function returns ERROR_SUCCESS, or returns an error value otherwise. If the value denoted by parameter lpszValue is not found, the function returns an error value. On receiving this error value, the RemoveIESkin() function returns FALSE indicating that the deletion of registry value did not take place.

That's it!

Really! That ends all the important code of this utility. Rest of the bits and pieces can be found in the source code. Once you start experimenting with various bmp files using this utility, you can make your IE look really cool. Also, as a side effect, your outlook express will also start flaunting this new skin.

You can use this code to develop a full-fledged IE customization utility, which could have a custom title, custom revolving logo, brand logo etc. by setting the appropriate registry values. The details about these registry settings can be obtained form the MSDN site. Happy coding and debugging ;)