In MFC dialog application dialog window to draw an area, the onpaint () by BitBIt function will display the bitmap resources in this area, the image is larger, can only display a part of me wants to through the mouse to drag the image, in turn, can see every part, double buffer how to implement, can't see a lot of, I am novice, looks at each prawn teach, not very grateful!

CodePudding user response:

 
BOOL CDragBmpDlg: : OnEraseBkgnd (pDC) CDC * 
{
//TODO: Add your message handler code here and/or call the default 
Return TRUE; 
//return CDialog: : OnEraseBkgnd (pDC); 
} 
Void CDragBmpDlg: : OnPaint () 
{
If (IsIconic ()) 
{
CPaintDC dc (this);//device context for painting 

SendMessage (WM_ICONERASEBKGND, (WPARAM) dc. GetSafeHdc (), 0). 

//Center icon in the client rectangle 
Int cxIcon=GetSystemMetrics (SM_CXICON); 
Int cyIcon=GetSystemMetrics (SM_CYICON); 
CRect the rect. 
GetClientRect (& amp; The rect); 
Int x=(the rect. Width () - cxIcon + 1)/2; 
Int y=(the rect. Height () - cyIcon + 1)/2; 

//Draw the icon 
Dc. DrawIcon (x, y, m_hIcon); 
} 
The else 
{
If (m_hBitmap) 
{
CPaintDC dc (this);//device context for painting 
CRect rc; 
GetClientRect (rc); 
The CDC memDC; 
MemDC. CreateCompatibleDC (& amp; Dc); 
HBITMAP old=(HBITMAP) memDC. SelectObject (m_hBitmap); 
Dc. BitBlt (0, 0, rc Width (), rc, Height (), & amp; MemDC m_MouseX, m_MouseY SRCCOPY); 
MemDC. SelectObject (old); 
} 
//CDialog: : OnPaint (); 
} 
} 

CDragBmpDlg: : CDragBmpDlg (pParent/*=NULL CWnd * */) 
: CDialog (CDragBmpDlg: : IDD, pParent) 
{
//{{AFX_DATA_INIT (CDragBmpDlg) 
//NOTE: the ClassWizard will add member initialization here 
//}} AFX_DATA_INIT 
//Note that LoadIcon does not require a subsequent DestroyIcon in Win32 
M_hIcon=AfxGetApp () - & gt; LoadIcon (IDR_MAINFRAME); 
M_hBitmap=(HBITMAP) LoadImage (AfxGetInstanceHandle (), 
"1. BMP," IMAGE_BITMAP, 0, 0, LR_LOADFROMFILE | LR_CREATEDIBSECTION); 
M_MouseX=0; 
M_MouseY=0; 
} 
Void CDragBmpDlg: : onm ouseMove (UINT nFlags, CPoint point) 
{
//TODO: Add your message handler code here and/or call the default 
The static CPoint ptLast; 
If (MK_LBUTTON==nFlags) 
{
SetCapture (); 
The ScreenToClient (& amp; Point); 
M_MouseX=point. X-ray ptLast. X; 
M_MouseY=point. Y - ptLast. Y; 
If (m_MouseX & lt; M_MouseX=0, 0); 
If (m_MouseY & lt; M_MouseY=0, 0); 
Invalidate (). 
} 
The else 
{
ReleaseCapture (); 
The ScreenToClient (& amp; Point); 
PtLast=point; 
} 
//CDialog: : onm ouseMove (nFlags, point); 
} 

CodePudding user response:

Void CDragBmpDlg: : onm ouseMove (UINT nFlags, CPoint point)
{
//TODO: Add your message handler code here and/or call the default
The static CPoint ptLast;
CRect rc;
GetClientRect (rc);
If (MK_LBUTTON==nFlags)
{
//SetCapture ();
The ScreenToClient (& amp; Point);
M_MouseX=point. X-ray ptLast. X;
M_MouseY=point. Y - ptLast. Y;
//
If (m_MouseX & lt; M_MouseX=0, 0);
If (m_MouseY & lt; M_MouseY=0, 0);
//
If ((m_MouseX + rc. Width ()) & gt;=m_bmpWidth) m_MouseX=m_bmpWidth - rc. Width ();
If ((m_MouseY + rc. Height ()) & gt;=m_bmpHeight) m_MouseY=m_bmpHeight - rc. Height ();
//afxDump & lt; Invalidate ().
}
The else
{
//ReleaseCapture ();
The ScreenToClient (& amp; Point);
PtLast=point;
//the accumulate for next dragging. - for (point. X-ray ptLast. X);
PtLast. X=m_MouseX;
PtLast. - y=m_MouseY;
}
//CDialog: : onm ouseMove (nFlags, point);
}


Init m_hBitmap=(HBITMAP) LoadImage (AfxGetInstanceHandle (),
"1. BMP," IMAGE_BITMAP, 0, 0, LR_LOADFROMFILE | LR_CREATEDIBSECTION);
BITMAP bm.
GetObject (m_hBitmap, sizeof (BITMAP), & amp; Bm);

M_bmpWidth=bm. BmWidth;
M_bmpHeight=bm. BmHeight;

CodePudding user response:

CPaintDC dc (this);//device context for painting
CRect rc;
GetClientRect (rc);
The CDC memDC;
MemDC. CreateCompatibleDC (& amp; Dc);
HBITMAP old=(HBITMAP) memDC. SelectObject (m_hBitmap);
Dc. BitBlt (0, 0, rc Width (), rc, Height (), & amp; MemDC m_MouseX, m_MouseY SRCCOPY);
MemDC. SelectObject (old);

The point is this

CodePudding user response:

The

reference 3 floor SWWLLX response:

CPaintDC dc (this);//device context for painting
CRect rc;
GetClientRect (rc);
The CDC memDC;
MemDC. CreateCompatibleDC (& amp; Dc);
HBITMAP old=(HBITMAP) memDC. SelectObject (m_hBitmap);
Dc. BitBlt (0, 0, rc Width (), rc, Height (), & amp; MemDC m_MouseX, m_MouseY SRCCOPY);
MemDC. SelectObject (old);

The focus is on the

This just shows the picture the designated area, can't drag

CodePudding user response:

refer to the second floor schlafenhamster response:

void CDragBmpDlg: : onm ouseMove (UINT nFlags, CPoint point)
{
//TODO: Add your message handler code here and/or call the default
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