? 結構體 Point 中方法Subtract()和Add()可用于在同一個坐標系中2點之間相對位置的計算:

public static Point Subtract(
?Point pt,
?Size sz
)

public static Point Add(
?Point pt,
?Size sz
)

而 Size 可以通過 Point 轉換, 如下Size的一個構造函數:
public Size(
?Point pt
)

下面以處于同一容器下(Form1)的2個組件 label1, label2 , 當拖曳第一個組件label1時, label2也同時跟著移動.

1. 定義全局字段:

private Point label1StartPos, offsetPoint;
private bool canMove = false;

2. 相關事件方法:

??????? private void label1_MouseDown(object sender, MouseEventArgs e)
??????? {
??????????? canMove = true;
??????????? label1StartPos = e.Location;
??????????? offsetPoint = Point.Subtract(label2.Location, new Size(label1.Location));
??????? }

??????? private void label1_MouseUp(object sender, MouseEventArgs e)
??????? {
??????????? canMove = false;
??????? }

??????? private void label1_MouseMove(object sender, MouseEventArgs e)
??????? {
??????????? if (canMove)
??????????? {
??????????????? label1.Location = this.PointToClient(Point.Subtract(label1.PointToScreen(e.Location), new Size(label1StartPos)));
??????????????? label2.Location = Point.Add(label1.Location, new Size(offsetPoint));
??????????? }
??????? }

?即可.

Point結構體中Subtract和Add方法在拖曳控件時的應用