按下按钮时如何创建所需数量的对象实例？c＃winforms

Question

In my code, every time button1 is pressed an instance of a picturebox called NOT is spawned in a panel. When the image is clicked and held on it can be dragged around. My question is every time button1 is pressed I want another pictureBox of the same properties to be created so that theoretically I could press button1 all day and drag around as many NOT picturebox objects around as I want. So far once the button is pressed only one instance of NOT is created and another cannot be spawned. So essentially how do make new unique instances of NOT every time button1 is pressed.

public Form1()
    {
        InitializeComponent();
        Drag();
    }

    private void button1_Click(object sender, EventArgs e)
    {
        spawnGate("not");
    }

    PictureBox NOT = new PictureBox();

    private Point startPoint = new Point();
    public void Drag()
    {
        NOT.MouseDown += (ss, ee) =>
        {
            if (ee.Button == System.Windows.Forms.MouseButtons.Left)
            {
                startPoint = Control.MousePosition;
            }
        };

        NOT.MouseMove += (ss, ee) =>
        {
            if (ee.Button == System.Windows.Forms.MouseButtons.Left)
            {
                Point temp = Control.MousePosition;
                Point res = new Point(startPoint.X - temp.X, startPoint.Y - temp.Y);

                NOT.Location = new Point(NOT.Location.X - res.X, NOT.Location.Y - res.Y);

                startPoint = temp;
            }
        };
    }

    public void spawnGate(string type)
    {
        switch (type)
        {
            case "not":
                NOT.Width = 100;
                NOT.Height = 50;
                NOT.Image = Properties.Resources.Not_gate;
                NOT.SizeMode = PictureBoxSizeMode.Zoom;
                workspace.Controls.Add(NOT);
            break;
        }
    }
}

Answer 1

Change NOT to a List<PictureBox> .

Then, add a new PictureBox instance to NOT in the spawnGate() method. Note that Drag() will need to be changed to take a PictureBox argument.

Edit : As requested in the comments, for the benefit of others visiting this question, here is exactly how the code would need to be changed to get the behavior requested by OP. Note that this design could and should be refactored in a few areas.

List<PictureBox> NOT = new List<PictureBox>();
Point startPoint = new Point();

public Form1()
{
    InitializeComponent();
    Drag();
}

private void button1_Click(object sender, EventArgs e)
{
    spawnGate();
}

public void spawnGate()
{
    var pictureBox = new PictureBox()
    {
        Width = 100,
        Height = 50,
        Image = Properties.Resources.Not_gate,
        SizeMode = PictureBoxSizeMode.Zoom       
    }

    Drag(pictureBox);

    NOT.Add(pictureBox);

    workspace.Controls.Add(pictureBox);
}

public void Drag(PictureBox pictureBox)
{
    pictureBox.MouseDown += (ss, ee) => 
    {
        if (ee.Button == System.Windows.Forms.MouseButtons.Left)
            startPoint = Control.MousePosition;
    };

    pictureBox.MouseMove += (ss, ee) =>
    {
        if (ee.Button == System.Windows.Forms.MouseButtons.Left)
        {
            Point temp = Control.MousePosition;
            Point res = new Point(startPoint.X - temp.X, startPoint.Y - temp.Y);

            pictureBox.Location = new Point(pictureBox.Location.X - pictureBox.X, pictureBox.Location.Y - res.Y);

            startPoint = temp;
        }
    };
}

Answer 2

You don't have to save the pointer to NOT on the form directly (or you could save them to a list if you need to call them at a later point).

public Form1()
{
    InitializeComponent();
}

private void button1_Click(object sender, EventArgs e)
{
    spawnGate("not");
}

// This list is optional, if you easily want to find them later
List<PictureBox> allNOTs = new List<PictureBox>();

public void spawnGate(string type)
{
    switch (type)
    {
        case "not":
            PictureBox NOT = new PictureBox();
            NOT.Width = 100;
            NOT.Height = 50;
            NOT.Image = Properties.Resources.Not_gate;
            NOT.SizeMode = PictureBoxSizeMode.Zoom;
            NOT.MouseDown += (ss, ee) =>
            {
                // Mouse down event code here
            };
            NOT.MouseMove += (ss, ee) =>
            {
                // Mouse move event code here
            };
            allNOTS.Add(NOT); // Optional if you easily want to find it later
            workspace.Controls.Add(NOT);
        break;
    }
}

}