Don't know how to get index from button list C# winForms-CodePudding

I am writing a program code for creating graphs from graph theory.

Clicking on a grid generates a graph node with the corresponding index. Buttons are generated on the right. I want the nodes to be connected by an edge when the button is clicked. For example, when you click on the button on line 1 and column 2, an edge will be drawn connecting circles 1 and 2.

enter image description here

Button generation code

List<Button> btnList = new List<Button>();
for (int z = 1; z <= count; z  )
                {
                    for (int x = 1; x <= count; x  )
                    {
                        Button btn = new Button();
                        btn.Text = 0.ToString();
                        btn.Location = new Point(z*30, x*30);
                        btn.Size = new System.Drawing.Size(30, 30);
                        btn.BackColor = System.Drawing.Color.White;
                        btn.MouseClick  = new System.Windows.Forms.MouseEventHandler(btnClick);
                        panel1.Controls.Add(btn);
                        btnList.Add(btn);
                    }
                }

The code of the event describing the click of the button

public void btnClick(object sender, EventArgs e)
        {
            Button button = (Button)sender;
            button.Text = (int.Parse(button.Text) 1).ToString();

            

            Graphics g = Graphics.FromImage(bmp);
            Pen pen = new Pen(Color.Black);
            //g.DrawLine(pen, );
            pictureBox1.Image = bmp;
        }

Maybe the question is very stupid, but I do not understand how to refer to the indexes of the pressed button in the btnClick function.

CodePudding user response：

You have, for every object in C#, a Tag property which is free. You can use it to store the coordinates of your button.

So, insert before you add the btn to the panel1.Controls, something like:

btn.Tag = new Point(z, x);

Then, in the btnClick delegate, to get back your coordinates, you use something like:

Button button = sender as Button;
Point p = button.Tag;
int z = p.X;
int x = p.Y;

You can keep the Button button = (Button)sender; The only difference is that casting can throw an exception but the keyword 'as' can't.

As I am writing this, I see the new comments and your reply. Tag isn't in the delegates like KeyDown but with the properties like Location, Size, Text, etc.

CodePudding user response：

You already store z and x:

btn.Location = new Point(z*30, x*30);

You can do this in the click handler to retrieve them:

int z = button.Location.X / 30;
int x = button.Location.Y / 30;

CodePudding user response：

Thanks for answers.

I add code when generation buttons

btn.Tag = new Point(z, x);

and i use btn.Tag when click on button

Point p = (Point)button.Tag;
            int z = p.X;
            int x = p.Y;