CDialogSK - A Skinnable Dialog Class

• Download demo project - 33 Kb
• Download source - 4 Kb

Introduction

This class is derived from the MFC CDialog. It supports the following features :-

1. If running on Windows 2000 or Windows XP, make any one color transparent so that you can see through regions of the dialog
2. If running on Windows 2000 or Windows XP, make the whole dialog translucent
3. Adding a bitmap to the back ground. The bitmap can be a resource, a BMP file, or a HBITMAP
4. Set style for background : Tile, Center, Stretch, resize dialog to the size of the bitmap
5. Can enable/disable moving the dialog by clicking anywhere in it

Previous to Windows 2000 creating skinned dialogs were a bit difficult. You needed to write functions that could parse through the back ground image and create a CRgn that defined the shape of the skin. This could be done using repetitive calls to CRgn::CombineRgn for part of the image you wanted to see on the dialog. After creating the whole region you need to call CWnd::SetWindowRgn with a handle to the combined CRgn object.

From Windows 2000 a new API SetLayeredWindowAttributes  has been added to User32.dll. This class uses that to create skinned dialogs. However the background bitmap feature is not dependent on OS version and can be used on any version of Windows.

Using The Code

The class can be used using the following steps

1. Add the files CDialogSK.h and CDialogSK.cpp to your project.

2. Include CDialogSK.h in the .h file for your dialog class

3. Replace all occurrences of "CDialog" with "CDialogSK" in the .h and .cpp files for your dialog class

4. If you plan to use a background image (bitmap) go to dialog properties, styles tab and make Style=Popup, Border=None, and uncheck the "Title Bar" check box.

5. At the end of OnInitDialog of your dialog class add calls to the appropriate methods in CDialogSK

   BOOL CSkinDialog_DemoDlg::OnInitDialog()
   {
       ...
       EnableEasyMove();  // enable moving of the dialog 
                          // by clicking anywhere in the dialog
       SetBitmap (IDB_BACKGROUND); // set background bitmap
       SetStyle (LO_RESIZE); // resize dialog to the size of the bitmap
       SetTransparentColor(RGB(0, 255, 0)); // set green as the 
                                            // transparent color
   
       return TRUE;
   }
   

6. If you want to change the window style later you can call any of these method anywhere in your code at run time.
7. If for example you want to make a circular dialog. Create a image which has a blue circle on a green background. Then call SetBitmap with the path to the image and call SetTransparentColor passing the color of background (green). This will remove the background from view and you will get a circular window.

Methods

The following methods are present in CDialogSK class

1. DWORD SetBitmap (HBITMAP hBitmap); Sets a background bitmap based on a HBITMAP.
2. DWORD SetBitmap (int nBitmap); Sets a background bitmap based on a resource ID.
3. DWORD SetBitmap (LPCTSTR lpszFileName); Sets a background bitmap based on a Windows bitmap (.bmp) file.
4. void SetStyle (LayOutStyle style); Sets the bitmap layout style. Can be any of LO_DEFAULT, LO_TILE (tile image), LO_CENTER (center image), LO_STRETCH (stretch image to fit dialog), LO_RESIZE (resize dialog to fit the image).
5. void EnableEasyMove (BOOL pEnable = TRUE); If called with TRUE then you can move the dialog by clicking anywhere in the client area of the dialog.
6. BOOL SetTransparent (BYTE bAlpha); Make the dialog as a whole transparent. Range is 0(transparent) - 255 (opaque). This works only on Windows2000 and above (WinXP).
7. BOOL SetTransparentColor (COLORREF col, BOOL bTrans = TRUE); Make a particular color transparent. This works only on Windows2000 and above (WinXP). This can be used to create dialog in which you can see through parts of the dialog. 

History

• This is the initial version. Date Posted: July 01, 2003