Question

MFC如何实现鼠标拖拽？

比如我按住左键不放，可以画图画线，直到松开后停止。
不要只说个用OnLButtonDown，我要详细点的过程，
或者是是按住左键，图片可以虽鼠标一起移动

Answer 1

bool g_bDrawFlag = false;
CPoint oldPoint;
void CTestDlg::OnLButtonDown(UINT nFlags, CPoint point)
{
CDialog::OnLButtonDown(nFlags, point);
g_bDrawFlag = true;
oldPoint = point;

}
void CTestDlg::OnMouseMove(UINT nFlags, CPoint point)
{
CDialog::OnMouseMove(nFlags, point);

if(g_bDrawFlag)
{
CClientDC dc(this);
MoveToEx(dc,oldPoint.x, oldPoint.y, NULL);
LineTo(dc, point.x, point.y);
oldPoint = point;
}
}
void CTestDlg::OnLButtonUp(UINT nFlags, CPoint point)
{
CDialog::OnLButtonUp(nFlags, point);
g_bDrawFlag = false;
}