拖动用鼠标拖动图片移动（Drag the picture move with mouse）

用鼠标拖动图片移动Drag the picture move with mouseDrag the picture to respond to the 3 mouse message

OnLBut t onD own, OnLBut t onUp, OnMous eMove

When the left button is pressed:

To determine if the image is pressed inside the image, if youcapture the picture

When the left key is released:

Release pictures

Mouse movement: according to the movement of the mouse,real-time redraw pictures

For this purpose, three class variables are set:

CPoint Pt; / / save the starting point

BOOL bcapture; / / image capture

CSize offsetsize; //offset of the mouse and the starting pointof the picture

The first is initialization:

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CMovePictureView: : CMovePictureView ()

{

Add construction code here / / TODO:

Bcapture=FALSE;

Pt.x=0;

Pt.y=0;

Offsetsize.cx=0;

Offsetsize.cy=0;

}

Then respond to the OnLButtonDown message

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Void CMovePictureView: : OnLButtonDown (UINT nFlags, CPointpoint)

{

CRect selrc (PT, size) ;

CClientDC DC (this) ;

OnPrepareDC (&dc) ;

CRgn rgn;

Rgn.CreateRectRgnIndirect (&selrc) ;

If (rgn.PtInRegion (point))

{

SetCapture () ;

B c ap tur e=T RUE;

CPoint RCPT (PT) ;

Offsetsize=point-rcpt;

SetCursor (LoadCursor (NULL, IDC_CROSS) ) ;

}

CScrollView: : OnLButtonDown (nFlags, point) ;

}

Respond to UP messages

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Void CMovePictureView: : OnLButtonUp (UINT nFlags, CPointpoint)

{

ReleaseCapture () ;

Bcapture=FALSE;

CScrollView: : OnLButtonUp (nFlags, point) ;

}

Respond to Move messages

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Void CMovePictureView: : OnMouseMove (UINT nFlags, CPointpoint)

{

If (bcapture)

{

CClientDC DC (this) ;

OnPrepareDC (&dc) ;

CRect oldrc (PT, size) ;

InvalidateRect (oldrc, TRUE) ;

Pt=point-offsetsize;

CRect newrc (PT, size) ;

InvalidateRect (newrc, TRUE) ;

}

CScrollView: : OnMouseMove (nFlags, point) ;

}

If you're drawing in the whole view or drawing in the entiredialog box, you can move the picture. But, if you're drawingin the CStatic picture control in the dialog box, there' s aproblem.

The reason is that: the mouse in response to the news, thecoordinates of CPoint points are the coordinates of the clientarea (dialog box because the response is a mouse message dialogbox so the coordinate system is a coordinate system, and thedialog box) our map is a CSTATIC picture control coordinatesystem and two coordinate systems are different, so there wasconfusion, cause we can not achieve the results you want.Solution: when the mouse message is received, screencoordinates are used as intermediate media. Specifically asfollows: first converts the CPoint from the dialog coordinatesystem to the screen coordinate system, and then converts thescreen coordinate system to the control coordinate system

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Void CShowImageDlg: : OnLButtonDown (UINT nFlags, CPoint point){

TODO: / / add your message handler code here and / or calldefault

CPoint orgPoint=point;

This->ClientToScreen (&point) ; //dialog box coordinates intoscreen coordinates

M_image.ScreenToClient (&point) ; / / screen coordinates intothe control coordinate system

CRect selRc (m_pt, m_size) ; / / coordinate control

CRgn rgn;

Rgn.CreateRectRgnIndirect (&selRc) ;

If (rgn.PtInRegion (point)) / / in the judgment of thecoordinate control, so you should first convert point tocoordinate control

{

SetCapture () ;

M_bc apt ure=TRUE;

CPoint RCPT (m_pt) ;

M_offsetsize=point-rcpt;

SetCursor (LoadCursor (NULL, IDC_CROSS) ) ;

}

CDialog: : OnLButtonDown (nFlags, orgPoint) ;

}

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Void CShowImageDlg: : OnLButtonUp (UINT nFlags, CPoint point){

TODO: / / add your message handler code here and / or calldefault

ReleaseCapture () ;

M_bcapture=FALSE;

CDialog: : OnLButtonUp (nFlags, point) ;

}

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Void CShowImageDlg: : OnMouseMove (UINT nFlags, CPoint point){

TODO: / / add your message handler code here and / or calldefault

CPoint orgPoint=point;

This->ClientToScreen (&point) ;

M_image.ScreenToClient (&point) ;

If (m_bcapture)

{

CRect oldRc (m_pt, m_size) ; / / coordinate control

M_image.ClientToScreen (&oldRc) ; / / into screen coordinatesThis->ScreenToClient (&oldRc) ; / / convert dialog boxcoordinates, then call the right InvalidateRect (oldRc, TRUE) ;because this function is invoked in the dialog box, so thedialog box coordinates coordinates

InvalidateRect (oldRc, TRUE) ;

M_pt=point-m_offsetsize;

CRect newRc (m_pt, m_size) ;

M_image.ClientToScreen (&newRc) ; // the same, will coordinatecontrol of newRc into the dialog box coordinates conversion,can call the InvalidateRect function correctly

This->ScreenToCl ient (&newRc) ;

InvalidateRect (newRc, TRUE) ;

}

CDialog: : OnMouseMove (nFlags, orgPoint) ;

}