MFC中画线时怎样确定鼠标移动到了两条线交点处？求高手解答

Question

初学MFC，想问一下在网格上画粗直线时，想从一个交叉点画到另一个，应该怎样确定鼠标移动到了网格交点处？求高手解答

Answer 1

初学MFC，现做一个鼠标测试软件，希望实现鼠标移动实时获取坐标，在左下角显示X，Y坐标值，并实现按下左键拖动划红线，按下右键画蓝线，按下中键画绿线，主要代码如下：
void CMSDlg::OnPaint()

{
CClientDC dc(this);
//显示X: Y: W:
COLORREF oldColor = dc.GetTextColor();
dc.SetBkMode(TRANSPARENT);
CFont font,fontChannel;
CFont* pOldFont=(CFont*)dc.SelectObject(&font);
CString strShowText;
fontChannel.CreatePointFont(300, _T("宋体"), &dc);
dc.SelectObject(&fontChannel);
strShowText.Format(_T("X:%4d Y:%4d W:%3d"),p.x,p.y,gl);
dc.SetTextColor(RGB(106,86,148)); //文本颜色

dc.TextOut(20,860,strShowText);

dc.SetTextColor(oldColor);

dc.SelectObject(pOldFont);
// CDialog::OnPaint();

}

void CMSDlg::OnMouseMove(UINT nFlags, CPoint point)

{
// TODO: Add your message handler code here and/or call default
if (LButDon||RButDon||MButDon)
{
CDC* pDC;
CPen newPen;
pDC=GetDC();
if(MButDon)
newPen.CreatePen(PS_DASHDOTDOT,2,RGB(0,255,0));
if (RButDon)
newPen.CreatePen(PS_DASHDOTDOT,2,RGB(0,0,255));
if (LButDon)
newPen.CreatePen(PS_DASHDOTDOT,2,RGB(255,0,0));

pDC-> SelectObject(newPen);

pDC->MoveTo(p);
pDC->LineTo(point);
ReleaseDC(pDC);
}
p=point;
RefreshPromptInfo();
CDialog::OnMouseMove(nFlags, point);
}

void CMSDlg::RefreshPromptInfo()
{
RECT rect; //刷新区域
rect.left=20; //区域最左端
rect.top=860;//区域最顶端
rect.right=rect.left+400;//宽
rect.bottom=rect.top+40;//高
InvalidateRect(&rect);
UpdateWindow();
}