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Replace a Window's Internal Scrollbar with a customdraw scrollbar Control

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17 Jun 2007CPOL3 min read 559.4K   9.7K   130   106
Shows how to replace a window's scrollbar with a skinable scrollbarctrl
Sample Image - skinscrollbar_demo.gif

Introduction

This is my first article. At first, I must express my thanks to CodeProject and all the selfless people.

I have tried to look for a sample to show me how to skin a window's internal scrollbar, but, unfortunately, I failed. Some days ago, I got inspiration: In order to skin a window's internal scrollbar, it may be possible to hide a window's scrollbar below a frame window whose size is smaller than the window, but is the window's parent.

I gave it a try and I succeeded!

Two Main Components

In my code, you will find two main components:

  1. CSkinScrollBar (derived from CScrollBar)
  2. CSkinScrollWnd (derived from CWnd)

CSkinScrollBar offers an owner draw scrollbar. What I have done is handle mouse input and paint message simply, and I do not intend to describe it in detail. If you are interested in it, you can look into my code.

CSkinScrollWnd is the Code's Core

C++
BOOL CSkinScrollWnd::SkinWindow(CWnd *pWnd,HBITMAP hBmpScroll)
{//create a frame windows set
 ASSERT(m_hWnd==NULL);
 m_hBmpScroll=hBmpScroll;

//calc scrollbar wid/hei according to the input bitmap handle
 BITMAP bm;
 GetObject(hBmpScroll,sizeof(bm),&bm);
 m_nScrollWid=bm.bmWidth/9;

 CWnd *pParent=pWnd->GetParent();
 ASSERT(pParent);
 RECT rcFrm,rcWnd;
 pWnd->GetWindowRect(&rcFrm);
 pParent->ScreenToClient(&rcFrm);
 rcWnd=rcFrm;
 OffsetRect(&rcWnd,-rcWnd.left,-rcWnd.top);
 UINT uID=pWnd->GetDlgCtrlID();

//remove original window's border style and add it to frame window
 DWORD dwStyle=pWnd->GetStyle();
 DWORD dwFrmStyle=WS_CHILD|SS_NOTIFY;
 DWORD dwFrmStyleEx=0;
 if(dwStyle&WS_VISIBLE) dwFrmStyle|=WS_VISIBLE;
 if(dwStyle&WS_BORDER)
 {
  dwFrmStyle|=WS_BORDER;
  pWnd->ModifyStyle(WS_BORDER,0);
  int nBorder=::GetSystemMetrics(SM_CXBORDER);
  rcWnd.right-=nBorder*2;
  rcWnd.bottom-=nBorder*2;
 }
 DWORD dwExStyle=pWnd->GetExStyle();
 if(dwExStyle&WS_EX_CLIENTEDGE)
 {
  pWnd->ModifyStyleEx(WS_EX_CLIENTEDGE,0);
  int nBorder=::GetSystemMetrics(SM_CXEDGE);
  rcWnd.right-=nBorder*2;
  rcWnd.bottom-=nBorder*2;
  dwFrmStyleEx|=WS_EX_CLIENTEDGE;
 }

//create frame window at original window's rectangle and 
//set its ID equal to original window's ID.
 this->CreateEx(dwFrmStyleEx,AfxRegisterWndClass(NULL),
	"SkinScrollBarFrame",dwFrmStyle,rcFrm,pParent,uID);

//create a limit window. it will clip target window's scrollbar. 
m_wndLimit.Create(NULL,"LIMIT",WS_CHILD|WS_VISIBLE,CRect(0,0,0,0),this,200);

//create my scrollbar ctrl
 m_sbHorz.Create(WS_CHILD,CRect(0,0,0,0),this,100);
 m_sbVert.Create(WS_CHILD|SBS_VERT,CRect(0,0,0,0),this,101);
 m_sbHorz.SetBitmap(m_hBmpScroll);
 m_sbVert.SetBitmap(m_hBmpScroll);

//change target's parent to limit window
 pWnd->SetParent(&m_wndLimit);

//attach CSkinScrollWnd data to target window's userdata. 

//Remark: use this code, obviously, you will never try to use userdata!!
 SetWindowLong(pWnd->m_hWnd,GWL_USERDATA,(LONG)this);

//subclass target window's wndproc
 m_funOldProc=(WNDPROC)SetWindowLong(pWnd->m_hWnd,GWL_WNDPROC,(LONG)HookWndProc);

 pWnd->MoveWindow(&rcWnd);

//set a timer. it will update scrollbar's information at times.

//I have tried to hook some messages so as to update scrollinfo timely.
//For example, WM_ERESEBKGND and WM_PAINT. 
//But with spy++'s aid, I found if the window's client area need not update,
// my hook proc would hook nothing except some control-depending interfaces. 
 SetTimer(TIMER_UPDATE,500,NULL);
 return TRUE;
}
static LRESULT CALLBACK
HookWndProc(HWND hwnd, UINT msg, WPARAM wp, LPARAM lp)
{//my hook function
 CSkinScrollWnd *pSkin=(CSkinScrollWnd*)GetWindowLong(hwnd,GWL_USERDATA);
 LRESULT lr=::CallWindowProc(pSkin->m_funOldProc,hwnd,msg,wp,lp);
 if(pSkin->m_bOp) return lr;
 if(msg==WM_ERASEBKGND)
 {//update scroll info
   SCROLLINFO si;
   DWORD dwStyle=::GetWindowLong(hwnd,GWL_STYLE);
   if(dwStyle&WS_VSCROLL)
   {
    memset(&si,0,sizeof(si));
    si.cbSize=sizeof(si);
    si.fMask=SIF_ALL;
    ::GetScrollInfo(hwnd,SB_VERT,&si);
    pSkin->m_sbVert.SetScrollInfo(&si);
    pSkin->m_sbVert.EnableWindow(si.nMax>=si.nPage);
   }
   if(dwStyle&WS_HSCROLL)
   {
    memset(&si,0,sizeof(si));
    si.cbSize=sizeof(si);
    si.fMask=SIF_ALL;
    ::GetScrollInfo(hwnd,SB_HORZ,&si);
    pSkin->m_sbHorz.SetScrollInfo(&si);
    pSkin->m_sbHorz.EnableWindow(si.nMax>=si.nPage);
   }
 }else if(msg==WM_NCCALCSIZE && wp)
 {//recalculate scroll bar display area.
   LPNCCALCSIZE_PARAMS pNcCalcSizeParam=(LPNCCALCSIZE_PARAMS)lp;
   DWORD dwStyle=::GetWindowLong(hwnd,GWL_STYLE);
   DWORD dwExStyle=::GetWindowLong(hwnd,GWL_EXSTYLE);
   BOOL  bLeftScroll=dwExStyle&WS_EX_LEFTSCROLLBAR;
   int nWid=::GetSystemMetrics(SM_CXVSCROLL);
   if(dwStyle&WS_VSCROLL) 
   {
    if(bLeftScroll)
     pNcCalcSizeParam->rgrc[0].left-=nWid-pSkin->m_nScrollWid;
    else
     pNcCalcSizeParam->rgrc[0].right+=nWid-pSkin->m_nScrollWid;
   }
   if(dwStyle&WS_HSCROLL) pNcCalcSizeParam->rgrc[0].bottom+=nWid-pSkin->m_nScrollWid;
   
   RECT rc,rcVert,rcHorz;
   ::GetWindowRect(hwnd,&rc);
   ::OffsetRect(&rc,-rc.left,-rc.top);
   
   nWid=pSkin->m_nScrollWid;
   if(bLeftScroll)
   {
    int nLeft=pNcCalcSizeParam->rgrc[0].left;
    int nBottom=pNcCalcSizeParam->rgrc[0].bottom;
    rcVert.right=nLeft;
    rcVert.left=nLeft-nWid;
    rcVert.top=0;
    rcVert.bottom=nBottom;
    rcHorz.left=nLeft;
    rcHorz.right=pNcCalcSizeParam->rgrc[0].right;
    rcHorz.top=nBottom;
    rcHorz.bottom=nBottom+nWid;
   }else
   {
    int nRight=pNcCalcSizeParam->rgrc[0].right;
    int nBottom=pNcCalcSizeParam->rgrc[0].bottom;
    rcVert.left=nRight;
    rcVert.right=nRight+nWid;
    rcVert.top=0;
    rcVert.bottom=nBottom;
    rcHorz.left=0;
    rcHorz.right=nRight;
    rcHorz.top=nBottom;
    rcHorz.bottom=nBottom+nWid;
   }
   if(dwStyle&WS_VSCROLL && dwStyle&WS_HSCROLL)
   {
    pSkin->m_nAngleType=bLeftScroll?1:2;
   }else
   {
    pSkin->m_nAngleType=0;
   }
   if(dwStyle&WS_VSCROLL)
   {
    pSkin->m_sbVert.MoveWindow(&rcVert);
    pSkin->m_sbVert.ShowWindow(SW_SHOW);
   }else
   {
    pSkin->m_sbVert.ShowWindow(SW_HIDE);
   }
   if(dwStyle&WS_HSCROLL)
   {
    pSkin->m_sbHorz.MoveWindow(&rcHorz);
    pSkin->m_sbHorz.ShowWindow(SW_SHOW);
   }else
   {
    pSkin->m_sbHorz.ShowWindow(SW_HIDE);
   }
   pSkin->PostMessage(UM_DESTMOVE,dwStyle&WS_VSCROLL,bLeftScroll);
 }
 return lr;
}

//the only global function
//param[in] CWnd *pWnd: target window
//param[in] HBITMAP hBmpScroll: bitmap handle used by scrollbar control.
//return CSkinScrollWnd*:the frame pointer

CSkinScrollWnd* SkinWndScroll(CWnd *pWnd,HBITMAP hBmpScroll);

With the help of my code, you just need to add a line of code in your code. For example, assume you have a treectrl in a window and you want to replace it's scrollbar. At first, you give it a name m_ctrlTree. The next step is when it gets initialized, add a line like this:

C++
SkinWndScroll(&m_ctrlTree,hBmpScroll)

How To Test My Project?

There are 4 types of controls in the interface, including listbox, treectrl, editctrl, richeditctrl respectively. Clicking list_addstring button will fill listctrl and you will see a left scrollbar. Clicking tree_addnode button will fill treectrl and you may see two ownerdraw scrollbars replace its internal scrollbar. Input text in two editboxes to see whether it works.

How To Prepare Your Scrollbar Bitmap?

Both vertical and horizontal scrollbars require 4 image segments. They are arrow-up/arrow-left, slide, thumb and arrow-down/arrow-right. Each of them includes 3 states: normal, hover, press. (It is possible to extend support for state easily. Because I'm not good at image processing, the sample bitmap came from a software's resource.) Beside those segments, the bitmap includes two angle segments located at bitmap's right.

Sample image

Now I Want to Show You the Problems I Have Encountered

  1. When I began this code, I tried to use a scrollbarctrl to cover the window's internal scrollbar. In my mind, only if my scrollbar window's Z order is higher, it will work well. But in fact, it does not work. Although my scrollbar window's z-order is higher, when mouse moves to scrollbar area, the internal scrollbar will render immediately. I have to add a new window as a frame to the target window.
  2. At first, I did not intend to support leftscrollbar style, and my code worked well. Finally, I decided to support it. But what makes me depressed is that it does not work any more. After spending a lot of time on debugging, I found it's wrong to move the window in the subclass callback function. So I defined a user message, and posted the message to the message queue.

How To Apply It to a ListCtrl?

Thanks to kangcorn for finding the problem.

When applying it to ListCtrl, dragging the thumb box will have no effect. I tried my best to deal with it. Now I show you an alternate method.

I derive a new class from CListCtrl and handle WM_VSCROLL/WM_HSCROLL with a sbcode equal to SB_THUMBTRACK.

For example:

C++
LRESULT CListCtrlEx::WindowProc(UINT message, WPARAM wParam, LPARAM lParam) 
{
 if(message==WM_VSCROLL||message==WM_HSCROLL)
 {
  WORD sbCode=LOWORD(wParam);
  if(sbCode==SB_THUMBTRACK
   ||sbCode==SB_THUMBPOSITION)
  {
   SCROLLINFO siv={0};
   siv.cbSize=sizeof(SCROLLINFO);
   siv.fMask=SIF_ALL;
   SCROLLINFO sih=siv;
   int nPos=HIWORD(wParam);
   CRect rcClient;
   GetClientRect(&rcClient);
   GetScrollInfo(SB_VERT,&siv);
   GetScrollInfo(SB_HORZ,&sih);
   SIZE sizeAll;
   if(sih.nPage==0) 
    sizeAll.cx=rcClient.right;
   else
    sizeAll.cx=rcClient.right*(sih.nMax+1)/sih.nPage ;
   if(siv.nPage==0)
    sizeAll.cy=rcClient.bottom;
   else
    sizeAll.cy=rcClient.bottom*(siv.nMax+1)/siv.nPage ;
   
   SIZE size={0,0};
   if(WM_VSCROLL==message)
   {
    size.cx=sizeAll.cx*sih.nPos/(sih.nMax+1);
    size.cy=sizeAll.cy*(nPos-siv.nPos)/(siv.nMax+1);
   }else
   {
    size.cx=sizeAll.cx*(nPos-sih.nPos)/(sih.nMax+1);
    size.cy=sizeAll.cy*siv.nPos/(siv.nMax+1);
   }
   Scroll(size);
   return 1;
  }
 }
 return CListCtrl::WindowProc(message, wParam, lParam);
}

Ok, that's all. Hope it will be helpful to you. Any suggestions will be welcome.

History

  • 2007-03-07
    • Fixed a bug of skinscrollwnd.cpp in which a wrong compare was done. Thanks to tHeWiZaRdOfDoS for reporting it to me.
  • 2007.1.23
    • Tested the project carefully and made some optimizations
  • 2007.1.22
    • Fixed a scrollbar's zero div bug, modified scrollbar's auto scroll codes
  • 2006.12.22
    • Modified code to apply it to combo ctrl
  • 2006.7.26
    • Showed a method for applying it to ListCtrl, etc.
  • 2006.7.12
    • Fixed a scrollbar's bug
  • 2006.7.9
    • Finished a primary frame

License

This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)


Written By
Software Developer (Junior)
China China
This member has not yet provided a Biography. Assume it's interesting and varied, and probably something to do with programming.

Comments and Discussions

 
AnswerRe: If I set the Tree control to no border I need to insert at least 9 items then the item will display. Pin
flyhigh4-Aug-08 15:36
professionalflyhigh4-Aug-08 15:36 
GeneralRe: If I set the Tree control to no border I need to insert at least 9 items then the item will display. Pin
AshesOfTime5-Aug-08 2:22
AshesOfTime5-Aug-08 2:22 
GeneralRe: If I set the Tree control to no border I need to insert at least 9 items then the item will display. Pin
flyhigh5-Aug-08 14:35
professionalflyhigh5-Aug-08 14:35 
AnswerRe: If I set the Tree control to no border I need to insert at least 9 items then the item will display. Pin
hcfalan1-Mar-09 22:07
hcfalan1-Mar-09 22:07 
Generalwm_lbuttondbclk Pin
dejfson25-Apr-08 11:25
dejfson25-Apr-08 11:25 
GeneralRe: wm_lbuttondbclk Pin
flyhigh25-Apr-08 21:54
professionalflyhigh25-Apr-08 21:54 
GeneralRe: wm_lbuttondbclk Pin
wonsea22-Jul-08 0:14
wonsea22-Jul-08 0:14 
Questionhow to increase the width of vertical and horizontal scrollbar Pin
rajneshmalik14-Nov-07 17:51
rajneshmalik14-Nov-07 17:51 
hi
can anybody solve my problem

thank u in advance

malik
AnswerRe: how to increase the width of vertical and horizontal scrollbar Pin
flyhigh17-Nov-07 14:34
professionalflyhigh17-Nov-07 14:34 
GeneralAdvice:remove OnTimer() and Add VScroll() & HScroll() message reflecting[modified] Pin
cbntrt6-Oct-07 0:13
cbntrt6-Oct-07 0:13 
GeneralRe: Advice:remove OnTimer() and Add VScroll() & HScroll() message reflecting[modified] Pin
flyhigh7-Oct-07 14:39
professionalflyhigh7-Oct-07 14:39 
GeneralRe: Advice:remove OnTimer() and Add VScroll() & HScroll() message reflecting[modified] Pin
cbntrt8-Oct-07 19:05
cbntrt8-Oct-07 19:05 
GeneralRe: Advice:remove OnTimer() and Add VScroll() & HScroll() message reflecting[modified] Pin
flyhigh8-Oct-07 20:37
professionalflyhigh8-Oct-07 20:37 
GeneralRe: Advice:remove OnTimer() and Add VScroll() & HScroll() message reflecting[modified] Pin
cbntrt8-Oct-07 22:12
cbntrt8-Oct-07 22:12 
GeneralRe: Advice:remove OnTimer() and Add VScroll() & HScroll() message reflecting[modified] Pin
flyhigh9-Oct-07 23:25
professionalflyhigh9-Oct-07 23:25 
NewsAdvice:remove OnTimer() and Add VScroll() & HScroll() message reflecting[modified] Pin
cbntrt5-Oct-07 23:14
cbntrt5-Oct-07 23:14 
QuestionHow to use this class without border? Pin
HoiN\ kyung-joon16-Apr-07 18:25
HoiN\ kyung-joon16-Apr-07 18:25 
AnswerRe: How to use this class without border? Pin
flyhigh19-Apr-07 1:31
professionalflyhigh19-Apr-07 1:31 
GeneralI wand to give your advice. Pin
HoiN\ kyung-joon16-Apr-07 16:40
HoiN\ kyung-joon16-Apr-07 16:40 
GeneralRe: I wand to give your advice. Pin
flyhigh16-Apr-07 17:29
professionalflyhigh16-Apr-07 17:29 
GeneralRe: I wand to give your advice. Pin
Jonghwa, Cho19-Aug-07 14:49
Jonghwa, Cho19-Aug-07 14:49 
QuestionProblems and a possible bug Pin
tHeWiZaRdOfDoS2-Mar-07 4:35
tHeWiZaRdOfDoS2-Mar-07 4:35 
AnswerRe: Problems and a possible bug Pin
flyhigh5-Mar-07 21:36
professionalflyhigh5-Mar-07 21:36 
Generalvery perfect! ye~~~ye~~~~~ Pin
Young E30-Jan-07 15:38
Young E30-Jan-07 15:38 
GeneralThank you! Pin
flute99924-Jan-07 19:27
flute99924-Jan-07 19:27 

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