一次又一次单击时，如何仅更改一个动态按钮的背景色？

Question

I have created 9 buttons dynamically and each with its own click event.

When a Button is clicked, it changes to red. If the Button is re-clicked, the button changes back to light gray.

For some reason when I click one button, all the other buttons change to red as well. How do I make it so that only the one that is clicked is red?

    private void frmToppings_Load(object sender, EventArgs e)
    {
        this.ControlBox = false;
        this.FormBorderStyle = FormBorderStyle.None;
        this.WindowState = FormWindowState.Maximized;
        formXsize = this.Size.Width;
        formYsize = this.Size.Height;
        path = dir + "deli1.jpg";
        Image img = Image.FromFile(path, true);
        this.BackgroundImage = img;
        this.BackgroundImageLayout = ImageLayout.Stretch;
        this.btns[0] = new Point(formXsize / 6 - formXsize / 7, formYsize / 3 - formYsize / 8);
        this.btns[1] = new Point(formXsize / 3 - formXsize / 7, formYsize / 3 - formYsize / 8);
        this.btns[2] = new Point(formXsize / 2 - formXsize / 7, formYsize / 3 - formYsize / 8);
        this.btns[3] = new Point(formXsize / 6 - formXsize / 7, formYsize / 2 - formYsize / 8);
        this.btns[4] = new Point(formXsize / 3 - formXsize / 7, formYsize / 2 - formYsize / 8);
        this.btns[5] = new Point(formXsize / 2 - formXsize / 7, formYsize / 2 - formYsize / 8);
        this.btns[6] = new Point(formXsize / 6 - formXsize / 7, formYsize / 1 - formYsize / 5);
        this.btns[7] = new Point(formXsize / 3 - formXsize / 7, formYsize / 1 - formYsize / 5);
        this.btns[8] = new Point(formXsize / 2 - formXsize / 7, formYsize / 1 - formYsize / 5);
        this.btnSize = new Size(formXsize / 7, formYsize / 7);
        this.txt[0] = new Point(formXsize / 2 + 70, formYsize / 10 - formYsize / 12);
        this.txtSize = new Size(formXsize - 950, formYsize - 40);
        this.Controls.Clear();
        DrawHoagieToppingsForm();
    }

    public void DrawHoagieToppingsForm()
    {
        Button btnMayo = new Button();
        btnMayo.Text = "Mayo";
        btnMayo.Location = btns[0];
        btnMayo.Size = btnSize;
        btnMayo.Click += new EventHandler(btnMayo_Click);
        btnMayo.BackColor = SystemColors.Control;
        Controls.Add(btnMayo);

        Button btnOil = new Button();
        btnOil.Text = "Oil";
        btnOil.Location = btns[1];
        btnOil.Size = btnSize;
        btnOil.Click += new EventHandler(btnOil_Click);
        btnOil.BackColor = SystemColors.Control;
        Controls.Add(btnOil);

        Button btnOnion = new Button();
        btnOnion.Text = "Onion";
        btnOnion.Location = btns[2];
        btnOnion.Size = btnSize;
        btnOnion.Click += new EventHandler(btnOnion_Click);
        btnOnion.BackColor = SystemColors.Control;
        Controls.Add(btnOnion);

        Button btnHotPeppers = new Button();
        btnHotPeppers.Text = "Hot Peppers";
        btnHotPeppers.Location = btns[3];
        btnHotPeppers.Size = btnSize;
        btnHotPeppers.Click += new EventHandler(btnHotPeppers_Click);
        btnHotPeppers.BackColor = SystemColors.Control;
        Controls.Add(btnHotPeppers);

        Button btnSweetPeppers = new Button();
        btnSweetPeppers.Text = "Sweet Peppers";
        btnSweetPeppers.Location = btns[4];
        btnSweetPeppers.Size = btnSize;
        btnSweetPeppers.Click += new EventHandler(btnSweetPeppers_Click);
        btnSweetPeppers.BackColor = SystemColors.Control;
        Controls.Add(btnSweetPeppers);

        Button btnOregano = new Button();
        btnOregano.Text = "Oregano";
        btnOregano.Location = btns[5];
        btnOregano.Size = btnSize;
        btnOregano.Click += new EventHandler(btnOregano_Click);
        btnOregano.BackColor = SystemColors.Control;
        Controls.Add(btnOregano);

        TextBox txtReceipt = new TextBox();
        txtReceipt.Multiline = true;
        txtReceipt.ReadOnly = true;
        txtReceipt.Location = txt[0];
        txtReceipt.Size = txtSize;
        Controls.Add(txtReceipt);

        Button btnBack = new Button();
        btnBack.Text = "Back";
        btnBack.Location = btns[6];
        btnBack.Size = btnSize;
        btnBack.Click += new EventHandler(btnBack_Click);
        Controls.Add(btnBack);

        Button btnCancel = new Button();
        btnCancel.Text = "Cancel";
        btnCancel.Location = btns[7];
        btnCancel.Size = btnSize;
        btnCancel.Click += new EventHandler(btnCancel_Click);
        Controls.Add(btnCancel);

        Button btnAddToOrder = new Button();
        btnAddToOrder.Text = "Add to Order";
        btnAddToOrder.Location = btns[8];
        btnAddToOrder.Size = btnSize;
        btnAddToOrder.Click += new EventHandler(btnAddToOrder_Click);
        Controls.Add(btnAddToOrder);
    }

    private void btnMayo_Click(object sender, EventArgs e)
    {
        this.BackColor = Color.Red;
    }

    private void btnOil_Click(object sender, EventArgs e)
    {
        //this.BackColor = Color.Red;
    }

    private void btnOnion_Click(object sender, EventArgs e)
    {
        //this.BackColor = Color.Red;
    }

    private void btnHotPeppers_Click(object sender, EventArgs e)
    {
        //this.BackColor = Color.Red;
    }

    private void btnSweetPeppers_Click(object sender, EventArgs e)
    {
        //this.BackColor = Color.Red;
    }

    private void btnOregano_Click(object sender, EventArgs e)
    {
        //this.BackColor = Color.Red;
    }

Answer 1

This can be compressed to one Click handler that you register with all Buttons. The trick is that the button that raised the event is transmitted in the "sender" argument. You just need to cast it, to have full access to the specific button:

private void btnCycleColors(object sender, EventArgs e)
{
  //This cast will fail if the event is registered with anything that is not a Button
  //But usually we can ignore that, as this will be quickly noticed
  Button caller = (Button)sender;

  if(caller.BackColor == X)
    caller.BackColor = Y;
}

Using switch...case with Pattern matching or maybe an array, you might even be able to have them properly cycle through a list without too much code.

Of course if you then later need to extract wich color the Button is on, that sounds like a faulty UI/UX design. Generally the values you need for calculations/opeartions should be kept in code behind. With the UI elements being meerely representations of the current values. That way you do not have to go and parse properties of Buttons to get the user selected values.

Answer 2

I found an answer that works:

public void single_button_Click(object sender, EventArgs e)
{
  Button btn = (Button)sender;
  if (btn.BackColor == Color.Red)
  {
    btn.BackColor = SystemColors.Control;
  }
  else if (btn.BackColor == SystemColors.Control)
  {
    btn.BackColor = Color.Red;
  }
}