Question

MFC 我想在对话框中实现鼠标实时绘图，麻烦大神看看我哪错了

主要代码如下，可是执行后对话框里一点反应都没有
void CTcpClientDlg::OnMouseMove(UINT nFlags, CPoint point)
{
CDC* pDc = GetDC();
CBrush newBrush;
CPen newPen;
newBrush.CreateSolidBrush(RGB(255,0,0));
newPen.CreatePen(PS_SOLID,5,RGB(255,0,0));
pDc->SelectObject(newBrush);
pDc->SelectObject(newPen);
pDc->LineTo(point.x,point.y);
// TODO: 在此添加消息处理程序代码和/或调用默认值
CDialog::OnMouseMove(nFlags, point);
}

Answer 1

void CTcpClientDlg::OnMouseMove(UINT nFlags, CPoint point) 
{
	static CPoint pt(-1,-1);
	CDC* pDc = GetDC();
	CBrush newBrush;
	CPen newPen;
	newBrush.CreateSolidBrush(RGB(255,0,0));
	newPen.CreatePen(PS_SOLID,5,RGB(255,0,0));
	CBrush *pb = (CBrush*)pDc->SelectObject(&newBrush);
	CPen *pp = (CPen*)pDc->SelectObject(&newPen);
	if(pt.x == -1)
		pDc->MoveTo(point.x,point.y);
	else
	{
		pDc->MoveTo(pt.x,pt.y);
		pDc->LineTo(point.x,point.y);
	}
	pt = point;

	pDc->SelectObject(pb);
	pDc->SelectObject(pp);
	ReleaseDC(pDc);

	// TODO: 在此添加消息处理程序代码和/或调用默认值
	CDialog::OnMouseMove(nFlags, point);
}

你的代码应该是能绘制的，不过有些其他方面的小问题。