引用多個實例化的圖片框

Question

我是C＃的新手，但想學習一下，如果我的語法不正確，請多多包涵。 我可以創建一個帶有按鈕的圖片框，它會顯示在屏幕上。 然后，我可以使用鼠標向下/鼠標移動功能在屏幕上移動它。 然后，我按下按鈕以實例化要創建的另一個圖片框，並且也可以移動該圖片框，但是當我嘗試移動第一個圖片框時，第二個圖片框將移動並瘋狂。 有沒有一種方法可以引用或標記實例化的框，以便當我單擊它們時可以在屏幕上移動它們？

public partial class Form1 : Form
{
    Point MP;
    private static Control PB;        

    public Form1()
    {
        InitializeComponent();
    }

    private void button1_Click(object sender, EventArgs e)
    {
        int picSizeX = Properties.Resources.police.Width / 3;
        int picSizeY = Properties.Resources.police.Height / 3;

        PictureBox pb = new PictureBox();
        pb.Location = new Point(100, 100);
        pb.Size = new Size(picSizeX, picSizeY);
        pb.Image = new Bitmap(Properties.Resources.police);
        pb.SizeMode = PictureBoxSizeMode.StretchImage;
        Controls.Add(pb);
        pb.Tag = "veh";
        PB = pb;

        pb.MouseDown += Pb_MouseDown;
        pb.MouseMove += Pb_MouseMove;
        pb.MouseHover += Pb_MouseHover;
    }

    private void Pb_MouseHover(object sender, EventArgs e)
    {
        PB.MouseHover += PB_MouseHover;
    }

    private void PB_MouseHover(object sender, EventArgs e)
    {

    }

    private void Pb_MouseDown(object sender, MouseEventArgs e)
    {
        MP = e.Location;
    }

    private void Pb_MouseMove(object sender, MouseEventArgs e)
    {
        if (e.Button == MouseButtons.Left)
        {
           PB.Left = e.X + PB.Left - MP.X;
           PB.Top = e.Y + PB.Top - MP.Y;
        }
    }
}

Answer 1

實際上，不需要在類級別具有控件。

在事件方法中，有一個稱為object sender的參數，其中包含對引發事件的控件/對象的引用。

Point MP;
//private Control PB; //commented out as it is not required

public Form1()
{
    InitializeComponent();
}

private void button1_Click(object sender, EventArgs e)
{
     int picSizeX = Properties.Resources.police.Width / 3;
     int picSizeY = Properties.Resources.police.Height / 3;

     PictureBox pb = new PictureBox();
     pb.Location = new Point(100, 100);
     pb.Size = new Size(picSizeX, picSizeY);
     pb.Image = new Bitmap(Properties.Resources.police);
     pb.SizeMode = PictureBoxSizeMode.StretchImage;
     Controls.Add(pb);
     pb.Tag = "veh";
     //PB = pb;

     pb.MouseDown += Pb_MouseDown;
     pb.MouseMove += Pb_MouseMove;
     pb.MouseHover += Pb_MouseHover;
}

private void Pb_MouseHover(object sender, EventArgs e)
{
     Control pbObj = sender as PictureBox; //sender refers to control that raised the event
     pbObj.MouseHover += PB_MouseHover;
}

private void PB_MouseHover(object sender, EventArgs e)
{

}

private void Pb_MouseDown(object sender, MouseEventArgs e)
{
    MP = e.Location;
}

private void Pb_MouseMove(object sender, MouseEventArgs e)
{
     Control pbObj = sender as PictureBox; //sender refers to control that raised the event

     if (e.Button == MouseButtons.Left)
     {
         pbObj.Left = e.X + pbObj.Left - MP.X;
         pbObj.Top = e.Y + pbObj.Top - MP.Y;
     }
}