Question

我正在使用MousePosition尝试确定用户在触发MouseDown事件后移动鼠标的方式。问题是我试图使用Point数据类型创建一个起始变量，我只希望这个Point用数据填充一次，但我在MouseDown中有它，所以我可以使用鼠标参数eX和eY来确定MouseDown事件的位置调用。这是我想到的

的一个例子

public void panel1_MouseDown(object sender, MouseEventArgs e)
{
    Point start = new Point(e.X, e.Y);
}
public void panel1_MouseMove(object sender, MouseEventArgs e)
{
    if(MousePosition.X > start.X)
    {
        Console.WriteLine("you have moved right");
    }
}

那么我怎样才能创建该起始变量一次，同时仍然可以访问e鼠标参数。以及如何访问panel1_MouseDown和panel1_MouseMove之间的变量？如果你看到一个更好的替代方案，那就太棒了！谢谢大家的帮助！

Answer 1

如果您厌恶定义新的类成员（由于某种原因），这是您可能拥有的最少的：

Point? start = null;
public void panel1_MouseDown(object sender, MouseEventArgs e)
{
    start = new Point(e.X, e.Y);
}
public void panel1_MouseUp(object sender, MouseEventArgs e)
{
    start = null;
}
public void panel1_MouseMove(object sender, MouseEventArgs e)
{
    if(start.HasValue)
      if(MousePosition.X > start.Value.X)
        Console.WriteLine("you have moved right");
}

但为了清晰（和功能），我还有一个额外的布尔变量：

bool mouseIsDown = false;
Point start;

public void panel1_MouseDown(object sender, MouseEventArgs e)
{
    start = new Point(e.X, e.Y);
    mouseIsDown = true;
}
public void panel1_MouseUp(object sender, MouseEventArgs e)
{
    mouseIsDown = false;
}
public void panel1_MouseMove(object sender, MouseEventArgs e)
{
    if(mouseIsDown)
      if(MousePosition.X > start.X)
        Console.WriteLine("you have moved right");
}

Answer 2

将您的起点声明为私有类变量

Private Point start;

public void panel1_MouseDown(object sender, MouseEventArgs e)
{
    this.start = new Point(e.X, e.Y);
}
public void panel1_MouseMove(object sender, MouseEventArgs e)
{
        if(MousePosition.X > this.start.X)
        {
            Console.WriteLine("you have moved right");
        }
}

重复点创建

2 个答案: