无边框对话框拖动改变大小的实现总结

同样是项目遇到的问题，要求是无边框的对话框要实现鼠标的拖动改变大小。无边框对话框跟有边框的实现肯定不一样喽。

我上网搜到一种方法是：

需要处理以下这三个消息:

WM_NCHITTEST  WM_SETCURSOR  WM_NCLBUTTONDOWN

消息处理函数:

UINT CXXXDlg::OnNcHitTest(UINT nHitTest, CPoint point)
{
 CRect rect;
 GetWindowRect(&rect);
 if(point.x <= rect.left+3)
    return HTLEFT;
 else if(point.x >= rect.right-3)
    return HTRIGHT;
 else if(point.y <= rect.top+3)
    return HTTOP;
 else if(point.y >= rect.bottom-3)
    return HTBOTTOM;
 else if(point.x <= rect.left+10 && point.y <= rect.top+10)
    return HTTOPLEFT;
 else if(point.x >= rect.right-10 && point.y <= rect.top+10)
    return HTTOPRIGHT;
 else if(point.x <= rect.left+10 && point.y >= rect.bottom-10)
    return HTBOTTOMLEFT;
 else if(point.x >= rect.right-10 && point.y >= rect.bottom-10)
    return HTBOTTOMRIGHT;
  
    return 0;
}
 
 
BOOL CXXXDlg::OnSetCursor(HWND hWnd, UINT nHitTest, UINT message)
{
    if(nHitTest == HTCAPTION || nHitTest == HTSYSMENU ||
       nHitTest == HTMENU || nHitTest == HTCLIENT)
   {
       SetCursor(LoadCursor(NULL, MAKEINTRESOURCE(IDC_ARROW)));
   }
   else if(nHitTest == HTTOP || nHitTest == HTBOTTOM)
   {
       SetCursor(LoadCursor(NULL, MAKEINTRESOURCE(IDC_SIZENS)));
   }
   else if(nHitTest == HTLEFT || nHitTest == HTRIGHT)
   {
       SetCursor(LoadCursor(NULL, MAKEINTRESOURCE(IDC_SIZEWE)));
   }
   else if(nHitTest == HTTOPLEFT || nHitTest == HTBOTTOMRIGHT)
   {
       SetCursor(LoadCursor(NULL, MAKEINTRESOURCE(IDC_SIZENWSE)));
   }
   else if(nHitTest == HTTOPRIGHT || nHitTest == HTBOTTOMLEFT)
   {
       SetCursor(LoadCursor(NULL, MAKEINTRESOURCE(IDC_SIZENESW)));
   }
   else
   {
       SetCursor(LoadCursor(NULL, MAKEINTRESOURCE(IDC_ARROW)));
    }
}
 
 
void CXXXDlg::OnNcLButtonDown(UINT nHitTest, CPoint point)
{
   if(nHitTest == HTTOP)
       SendMessage( WM_SYSCOMMAND, SC_SIZE | WMSZ_TOP, MAKELPARAM(point.x, point.y));
   else if(nHitTest == HTBOTTOM)
       SendMessage( WM_SYSCOMMAND, SC_SIZE | WMSZ_BOTTOM, MAKELPARAM(point.x, point.y));
   else if(nHitTest == HTLEFT)
       SendMessage( WM_SYSCOMMAND, SC_SIZE | WMSZ_LEFT, MAKELPARAM(point.x, point.y));
   else if(nHitTest == HTRIGHT)
       SendMessage( WM_SYSCOMMAND, SC_SIZE | WMSZ_RIGHT, MAKELPARAM(point.x, point.y));
   else if(nHitTest == HTTOPLEFT)
       SendMessage( WM_SYSCOMMAND, SC_SIZE | WMSZ_TOPLEFT, MAKELPARAM(point.x, point.y));
   else if(nHitTest == HTTOPRIGHT)
       SendMessage( WM_SYSCOMMAND, SC_SIZE | WMSZ_TOPRIGHT, MAKELPARAM(point.x, point.y));
   else if(nHitTest == HTBOTTOMLEFT)
       SendMessage( WM_SYSCOMMAND, SC_SIZE | WMSZ_BOTTOMLEFT, MAKELPARAM(point.x, point.y));
   else if(nHitTest == HTBOTTOMRIGHT)
       SendMessage(WM_SYSCOMMAND, SC_SIZE | WMSZ_BOTTOMRIGHT, MAKELPARAM(point.x, point.y));
}

上面的做法有点问题，像在判断时， 左右，上下先判断了，那左上，左下，右上，右下就没法做了。
所有就有了改进的方法：

UINT CTestDlg::OnNcHitTest( CPoint point )
{
CPoint ptCur;
CRect rect;
GetCursorPos( &ptCur );
GetWindowRect( &rect );

if( CRect(rect.left, rect.top, rect.left+3, rect.top+3).PtInRect( ptCur ) )  
return HTTOPLEFT;
else if( CRect(rect.right-3, rect.top, rect.right, rect.top+3).PtInRect( ptCur ) )
return HTTOPRIGHT;
else if( CRect(rect.left, rect.bottom-3, rect.left+3, rect.bottom).PtInRect( ptCur ) )
return HTBOTTOMLEFT;
else if( CRect(rect.right-3, rect.bottom-3, rect.right, rect.bottom).PtInRect( ptCur ) )
return HTBOTTOMRIGHT;
else if ( CRect(rect.left, rect.top, rect.left+3, rect.bottom).PtInRect( ptCur ) )
return HTLEFT;
else if( CRect(rect.right-3, rect.top, rect.right, rect.bottom).PtInRect( ptCur ) )
return HTRIGHT;
else if( CRect(rect.left, rect.top, rect.right-128, rect.top+3).PtInRect( ptCur ) ) // 128 Min,Max,Close
return HTTOP;
else if( CRect(rect.left, rect.bottom-3, rect.right, rect.bottom).PtInRect( ptCur ) )
return HTBOTTOM;

    return CDialog::OnNcHitTest(point);
}

BOOL CTestDlg::OnSetCursor(CWnd* pWnd, UINT nHitTest, UINT message) 
{
CPoint ptCur;
CRect rect;
GetCursorPos( &ptCur );
GetWindowRect( &rect );

if ( rect.Width() >= m_nCxFullScreen-3 && rect.Height() >= m_nCyFullScreen-3 )
return CDialog::OnSetCursor(pWnd, nHitTest, message);

if( CRect(rect.left, rect.top, rect.left+3, rect.top+3).PtInRect( ptCur ) || CRect(rect.right-3, rect.bottom-3, rect.right, rect.bottom).PtInRect( ptCur ) )
{
SetCursor(LoadCursor(NULL, MAKEINTRESOURCE(IDC_SIZENWSE)));
return 0;
}
else if( CRect(rect.left, rect.bottom-3, rect.left+3, rect.bottom).PtInRect( ptCur ) || CRect(rect.left, rect.bottom-3, rect.left+3, rect.bottom).PtInRect( ptCur ) )
{
SetCursor(LoadCursor(NULL, MAKEINTRESOURCE(IDC_SIZENESW)));
return 0;
}
else if( CRect(rect.left, rect.top, rect.right-128, rect.top+3).PtInRect( ptCur ) || CRect(rect.left, rect.bottom-3, rect.right, rect.bottom).PtInRect( ptCur ) )
{
SetCursor(LoadCursor(NULL, MAKEINTRESOURCE(IDC_SIZENS)));
return 0;
}
else if( CRect(rect.left, rect.top, rect.left+3, rect.bottom).PtInRect( ptCur ) || CRect(rect.right-3, rect.top, rect.right, rect.bottom).PtInRect( ptCur ) )
{
SetCursor(LoadCursor(NULL, MAKEINTRESOURCE(IDC_SIZEWE)));
return 0;
}

return CDialog::OnSetCursor(pWnd, nHitTest, message);
}

void CTestDlg::OnNcLButtonDown(UINT nHitTest, CPoint point)
{
switch( nHitTest )
{
case HTTOP:
SendMessage( WM_SYSCOMMAND, SC_SIZE | WMSZ_TOP, MAKELPARAM(point.x, point.y));
return;
case HTBOTTOM:
SendMessage( WM_SYSCOMMAND, SC_SIZE | WMSZ_BOTTOM, MAKELPARAM(point.x, point.y));
return;
case HTLEFT:
SendMessage( WM_SYSCOMMAND, SC_SIZE | WMSZ_LEFT, MAKELPARAM(point.x, point.y));
return;
case HTRIGHT:
SendMessage( WM_SYSCOMMAND, SC_SIZE | WMSZ_RIGHT, MAKELPARAM(point.x, point.y));
return;
case HTTOPLEFT:
SendMessage( WM_SYSCOMMAND, SC_SIZE | WMSZ_TOPLEFT, MAKELPARAM(point.x, point.y));
return;
case HTTOPRIGHT:
SendMessage( WM_SYSCOMMAND, SC_SIZE | WMSZ_TOPRIGHT, MAKELPARAM(point.x, point.y));
return;
case HTBOTTOMLEFT:
SendMessage( WM_SYSCOMMAND, SC_SIZE | WMSZ_BOTTOMLEFT, MAKELPARAM(point.x, point.y));
return;
case HTBOTTOMRIGHT:
SendMessage( WM_SYSCOMMAND, SC_SIZE | WMSZ_BOTTOMRIGHT, MAKELPARAM(point.x, point.y));
return;
default:
CDialog::OnNcLButtonDown( nHitTest, point );
}