以前看到有人開發的帶滾動條的大圖無刷新顯示框，不知道採用什麼技術開發的，基本功能可以，但是滾動條長度有時會超出圖形框，用戶體驗大打折扣。閒來無事時，決定自己動手寫一個。技術很簡單，就是從CWnd繼承一個窗口類，根據圖像大小自動顯示滾動條，由於知道圖形大小和窗口大小，滾動條的最大值就確定了，根據滾動條的位置就可以算出當前窗口影射到圖像上的位置，然後創建內存dc，從圖像上copy相應大小的圖形到內存dc上，然後複製到窗口dc上，這樣就大功告成，簡單吧。代碼如下：
#if !defined(AFX_BAR_H__90C0CEA8_EB58_4CC7_A33A_CEC11E8527AE__INCLUDED_)
#define AFX_BAR_H__90C0CEA8_EB58_4CC7_A33A_CEC11E8527AE__INCLUDED_
#if _MSC_VER > 1000
#pragma once
#endif // _MSC_VER > 1000
// Bar.h : header file
//
/////////////////////////////////////////////////////////////////////////////
// CShowBitmap window
class CShowBitmap : public CWnd
{
// Construction
public:
CShowBitmap();
// Attributes
public:
// Operations
public:
// Overrides
// ClassWizard generated virtual function overrides
//{{AFX_VIRTUAL(CShowBitmap)
//}}AFX_VIRTUAL
// Implementation
public:
virtual ~CShowBitmap();
// Generated message map functions
protected:
//{{AFX_MSG(CShowBitmap)
afx_msg void OnVScroll(UINT nSBCode, UINT nPos, CScrollBar* pScrollBar);
afx_msg void OnPaint();
afx_msg void OnHScroll(UINT nSBCode, UINT nPos, CScrollBar* pScrollBar);
afx_msg BOOL OnMouseWheel(UINT nFlags, short zDelta, CPoint pt);
afx_msg void OnLButtonDown(UINT nFlags, CPoint point);
afx_msg void OnMButtonDown(UINT nFlags, CPoint point);
afx_msg void OnRButtonDown(UINT nFlags, CPoint point);
//}}AFX_MSG
DECLARE_MESSAGE_MAP()
public:
void SetBitmap(HBITMAP hbit);
BOOL Create( LPCTSTR lpszWindowName, DWORD dwStyle, const RECT& rect, CWnd* pParentWnd, UINT nID, CCreateContext* pContext = NULL);
protected:
void DrawBmp(CDC *pDC);
HBITMAP m_hBit;
BOOL m_bHScroll;
BOOL m_bVScroll;
};
/////////////////////////////////////////////////////////////////////////////
//{{AFX_INSERT_LOCATION}}
// Microsoft Visual C++ will insert additional declarations immediately before the previous line.
#endif // !defined(AFX_BAR_H__90C0CEA8_EB58_4CC7_A33A_CEC11E8527AE__INCLUDED_)
///cpp file
// Bar.cpp : implementation file
//
#include "stdafx.h"
#include "ShowBitmap.h"
#ifdef _DEBUG
#define new DEBUG_NEW
#undef THIS_FILE
static char THIS_FILE[] = __FILE__;
#endif
#define INTSCROL 10
/////////////////////////////////////////////////////////////////////////////
// CShowBitmap
CShowBitmap::CShowBitmap()
{
m_hBit = NULL;
m_bHScroll = FALSE;
m_bVScroll = FALSE;
}
CShowBitmap::~CShowBitmap()
{
}
BEGIN_MESSAGE_MAP(CShowBitmap, CWnd)
//{{AFX_MSG_MAP(CShowBitmap)
ON_WM_VSCROLL()
ON_WM_PAINT()
ON_WM_HSCROLL()
ON_WM_MOUSEWHEEL()
ON_WM_LBUTTONDOWN()
ON_WM_MBUTTONDOWN()
ON_WM_RBUTTONDOWN()
//}}AFX_MSG_MAP
END_MESSAGE_MAP()
/////////////////////////////////////////////////////////////////////////////
// CShowBitmap message handlers
void CShowBitmap::OnVScroll(UINT nSBCode, UINT nPos, CScrollBar* pScrollBar)
{
// TODO: Add your message handler code here and/or call default
int minpos;
int maxpos;
GetScrollRange(SB_VERT,&minpos, &maxpos);
maxpos = GetScrollLimit(SB_VERT);
// Get the current position of scroll box.
int curpos = GetScrollPos(SB_VERT);
// Determine the new position of scroll box.
switch (nSBCode)
{
case SB_TOP: // Scroll to far up.
curpos = minpos;
break;
case SB_BOTTOM: // Scroll to far right.
curpos = maxpos;
break;
case SB_ENDSCROLL: // End scroll.
break;
case SB_LINEUP: // Scroll left.
if (curpos > minpos)
{
if(curpos - minpos >= INTSCROL)
curpos -= INTSCROL;
else
curpos = minpos;
}
break;
case SB_LINEDOWN: // Scroll right.
if (curpos < maxpos)
{
if(maxpos - curpos >= INTSCROL)
curpos += INTSCROL;
else
curpos = maxpos;
}
break;
case SB_PAGEUP: // Scroll one page left.
{
// Get the page size.
SCROLLINFO info;
GetScrollInfo(SB_VERT,&info, SIF_ALL);
if (curpos > minpos)
curpos = max(minpos, curpos - (int) info.nPage);
}
break;
case SB_PAGEDOWN: // Scroll one page right.
{
// Get the page size.
SCROLLINFO info;
GetScrollInfo(SB_VERT,&info, SIF_ALL);
if (curpos < maxpos)
curpos = min(maxpos, curpos + (int) info.nPage);
}
break;
case SB_THUMBPOSITION: // Scroll to absolute position. nPos is the position
curpos = nPos; // of the scroll box at the end of the drag operation.
break;
case SB_THUMBTRACK: // Drag scroll box to specified position. nPos is the
curpos = nPos; // position that the scroll box has been dragged to.
break;
}
// Set the new position of the thumb (scroll box).
SetScrollPos(SB_VERT,curpos);
//CRect rc;
// GetClientRect(rc);
DrawBmp(GetDC());
CWnd::OnVScroll(nSBCode, nPos, pScrollBar);
// InvalidateRect(rc);
}
BOOL CShowBitmap::Create( LPCTSTR lpszWindowName, DWORD dwStyle, const RECT& rect, CWnd* pParentWnd, UINT nID, CCreateContext* pContext)
{
CString strCls;
// ´´½¨±à¼¿ò
strCls = AfxRegisterWndClass(CS_CLASSDC|CS_SAVEBITS, LoadCursor(NULL, IDC_ARROW));
BOOL bRet = CWnd::Create(strCls,lpszWindowName,dwStyle|WS_BORDER|WS_VSCROLL|WS_HSCROLL|WS_CHILD|WS_VISIBLE,rect,pParentWnd,nID,pContext);
if(bRet)
{
ModifyStyleEx(0,WS_EX_TRANSPARENT |WS_EX_CLIENTEDGE );
ShowScrollBar(SB_BOTH,FALSE);
}
return bRet;
}
void CShowBitmap::SetBitmap(HBITMAP hbit)
{
m_hBit = hbit;
ShowScrollBar(SB_BOTH,FALSE);
m_bHScroll = FALSE;
m_bVScroll = FALSE;
CRect rc;
GetClientRect(rc);
// Çå¿Õ½çÃæ
if(m_hBit == NULL)
{
DrawBmp(GetDC());
return;
}
// ÉèÖÃscroll
// µÃµ½Í¼ÐÎÐÅÏ¢
BITMAP bi;
::GetObject(m_hBit,sizeof(BITMAP),&bi);
m_bHScroll = (bi.bmWidth - rc.Width()) > 0;
m_bVScroll = (bi.bmHeight - rc.Height()) > 0;
SCROLLINFO scinfo;
scinfo.cbSize = sizeof(SCROLLINFO);
scinfo.fMask = SIF_ALL;
scinfo.nMin = 0;
scinfo.nTrackPos = 0;
scinfo.nPos = 0;
ShowScrollBar(SB_HORZ,m_bHScroll);
ShowScrollBar(SB_VERT,m_bVScroll);
GetClientRect(rc);
if(m_bHScroll)
{
scinfo.nMax = bi.bmWidth;
scinfo.nPage = rc.Width();
SetScrollInfo(SB_HORZ,&scinfo);
}
if(m_bVScroll)
{
scinfo.nMax = bi.bmHeight;
scinfo.nPage = rc.Height();
SetScrollInfo(SB_VERT,&scinfo);
}
DrawBmp(GetDC());
}
void CShowBitmap::DrawBmp(CDC *pDC)
{
CRect rc;
GetClientRect(rc);
if(m_hBit == NULL)
{
CBitmap bitTmp;
CDC memDc;
memDc.CreateCompatibleDC(NULL);
bitTmp.CreateCompatibleBitmap(pDC,rc.Width(),rc.Height());
CBitmap * pOld = (CBitmap*)memDc.SelectObject(&bitTmp);
CBrush brush;
brush.CreateSolidBrush(RGB(255,255,255));
memDc.FillRect(rc,&brush);
pDC->BitBlt(0,0,rc.Width(),rc.Height(),&memDc,0,0,SRCCOPY);
memDc.SelectObject(pOld);
return;
}
int x =0,y = 0;
BITMAP bi;
::GetObject(m_hBit,sizeof(BITMAP),&bi);
int nH,nW;
int nDx,nDy;
nDx = 0;
nDy = 0;
if(m_bVScroll) // ÊúÖ±¹ö¶¯Ìõ
{
y = GetScrollPos(SB_VERT);
nH = rc.Height();
}
else
{
nH = bi.bmHeight;
nDy = (rc.Height() - nH)/2;
}
if(m_bHScroll) // ˮƽ¹ö¶¯Ìõ
{
x = GetScrollPos(SB_HORZ);
nW = rc.Width();
}
else
{
nW = bi.bmWidth;
nDx = (rc.Width() - nW)/2;
}
CBitmap bitTmp,bit;
CDC memDc,dc;
bit.Attach(m_hBit);
memDc.CreateCompatibleDC(NULL);
CBitmap * pOldbmp = memDc.SelectObject(&bit);
dc.CreateCompatibleDC(NULL);
bitTmp.CreateCompatibleBitmap(pDC,rc.Width(),rc.Height());
CBitmap * pOld = (CBitmap*)dc.SelectObject(&bitTmp);
CBrush brush;
brush.CreateSolidBrush(RGB(255,255,255));
dc.FillRect(rc,&brush);
dc.SetStretchBltMode(COLORONCOLOR);
dc.StretchBlt(nDx,nDy,nW,nH,&memDc,x,y,nW,nH,SRCCOPY);
pDC->BitBlt(0,0,rc.Width(),rc.Height(),&dc,0,0,SRCCOPY);
dc.SelectObject(pOld);
memDc.SelectObject(pOldbmp);
bit.Detach();
/* CBitmap bitTmp;
CDC dc;
dc.CreateCompatibleDC(pDC);
bitTmp.CreateCompatibleBitmap(pDC,100,100);
CBitmap * pOld = (CBitmap*)dc.SelectObject(&bitTmp);
CBrush brush;
brush.CreateSolidBrush(RGB(255,255,255));
dc.FillRect(CRect(0,0,100,100),&brush);
dc.MoveTo(10,10);
dc.LineTo(100,10);
dc.SelectObject(pOld);
pDC->SelectObject(bitTmp);
// bitTmp.Detach();*/
}
void CShowBitmap::OnPaint()
{
CPaintDC dc(this); // device context for painting
DrawBmp(&dc);
/* CDC * pDC;
pDC = CDC::FromHandle(::GetDC(NULL));
CBitmap bitTmp;
CDC dc;
dc.CreateCompatibleDC(pDC);
bitTmp.CreateCompatibleBitmap(pDC,100,100);
CBitmap * pOld = (CBitmap*)dc.SelectObject(&bitTmp);
CBrush brush;
brush.CreateSolidBrush(RGB(255,255,255));
dc.FillRect(CRect(0,0,100,100),&brush);
dc.MoveTo(10,10);
dc.LineTo(100,10);
dc.SelectObject(pOld);
pDC->SelectObject(bitTmp);*/
}
void CShowBitmap::OnHScroll(UINT nSBCode, UINT nPos, CScrollBar* pScrollBar)
{
int minpos;
int maxpos;
GetScrollRange(SB_VERT,&minpos, &maxpos);
maxpos = GetScrollLimit(SB_HORZ);
// Get the current position of scroll box.
int curpos = GetScrollPos(SB_HORZ);
// Determine the new position of scroll box.
switch (nSBCode)
{
case SB_LEFT: // Scroll to far left.
curpos = minpos;
break;
case SB_RIGHT: // Scroll to far right.
curpos = maxpos;
break;
case SB_ENDSCROLL: // End scroll.
break;
case SB_LINELEFT: // Scroll left.
if (curpos > minpos)
{
if(curpos - minpos >= INTSCROL)
curpos -= INTSCROL;
else
curpos = minpos;
}
break;
case SB_LINERIGHT: // Scroll right.
if (curpos < maxpos)
{
if(maxpos - curpos >= INTSCROL)
curpos += INTSCROL;
else
curpos = maxpos;
}
break;
case SB_PAGELEFT: // Scroll one page left.
{
// Get the page size.
SCROLLINFO info;
GetScrollInfo(SB_HORZ,&info, SIF_ALL);
if (curpos > minpos)
curpos = max(minpos, curpos - (int) info.nPage);
}
break;
case SB_PAGERIGHT: // Scroll one page right.
{
// Get the page size.
SCROLLINFO info;
GetScrollInfo(SB_HORZ,&info, SIF_ALL);
if (curpos < maxpos)
curpos = min(maxpos, curpos + (int) info.nPage);
}
break;
case SB_THUMBPOSITION: // Scroll to absolute position. nPos is the position
curpos = nPos; // of the scroll box at the end of the drag operation.
break;
case SB_THUMBTRACK: // Drag scroll box to specified position. nPos is the
curpos = nPos; // position that the scroll box has been dragged to.
break;
}
// Set the new position of the thumb (scroll box).
SetScrollPos(SB_HORZ,curpos);
DrawBmp(GetDC());
CWnd::OnHScroll(nSBCode, nPos, pScrollBar);
}
BOOL CShowBitmap::OnMouseWheel(UINT nFlags, short zDelta, CPoint pt)
{
// TODO: Add your message handler code here and/or call default
if(m_bVScroll)
{
if(zDelta > 0) // ÏòÉÏ
OnVScroll(SB_LINEUP,0,NULL);
else // ÏòÏÂ
OnVScroll(SB_LINEDOWN,0,NULL);
}
return CWnd::OnMouseWheel(nFlags, zDelta, pt);
}
void CShowBitmap::OnLButtonDown(UINT nFlags, CPoint point)
{
// TODO: Add your message handler code here and/or call default
this->SetFocus();
CWnd::OnLButtonDown(nFlags, point);
}
void CShowBitmap::OnMButtonDown(UINT nFlags, CPoint point)
{
// TODO: Add your message handler code here and/or call default
this->SetFocus();
CWnd::OnMButtonDown(nFlags, point);
}
void CShowBitmap::OnRButtonDown(UINT nFlags, CPoint point)
{
// TODO: Add your message handler code here and/or call default
this->SetFocus();
CWnd::OnRButtonDown(nFlags, point);
}
