Draw a line when you click a botton

Question

Draw a line when you click a botton

Calvinche 21

Hi!

I am doing a university project and I have to make and interface that show different routes depending the button you click.

So I have different buttons on interface and his method of clicking which is like this:

private void button_tienda1_Click(object sender, EventArgs e)  
        {  
            label_boton_pulsado.Text = "You choose A";  
        }

As you can see, in this method I am able to change the text of a label that I have called ("label_boton_pulsado")

Then I have a method that ables to draw a line on a picture that I loaded.

private void pictureBox1_Paint(object sender, PaintEventArgs e)  
        {  
            //Event for drawing lines  
            Graphics g = e.Graphics;  
            //Configuration of the pencil  
            Pen greenPen = new Pen(Color.FromArgb(255, 0, 255, 0), 5);  
  
            //Draw  
            g.DrawLine(greenPen, 220, 370, 220, 290);  
        }

What I need is that the line only appears when the button is clicked. If it is not clicked, I do not want the line to appear.
Hope that someone could help me, thank you!

Accepted answer

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Answer 1

Viorel 122.6K

Try something like this:

private void button_tienda1_Click(object sender, EventArgs e)  
{  
    label_boton_pulsado.Text = "You choose A";  
    drawLine = true;  
    Invalidate( );  
}  
  
bool drawLine = false;  
  
private void pictureBox1_Paint(object sender, PaintEventArgs e)  
{  
    if( drawLine)  
    {  
        Graphics g = e.Graphics;  
        //Configuration of the pencil  
        Pen greenPen = new Pen(Color.FromArgb(255, 0, 255, 0), 5);  
        //Draw  
        g.DrawLine(greenPen, 220, 370, 220, 290);  
    }  
}

Calvinche 21 Reputation points

2022-11-23T19:26:01.613+00:00

The code seems to be ok because it doesn't appear any error, but when I execute the program and click on the button, the line doesn't appear. Maybe it draws but behing the image.
Viorel 122.6K Reputation points

2022-11-23T19:30:02.677+00:00

Try replacing Invalidate( ) with pictureBox1.Invalidate( ).
Calvinche 21 Reputation points

2022-11-23T19:36:40.953+00:00

YES!
It works!! Thank you so much.

Answer 2

@Viorel And do you know how can I delete that first route if I click another button in order to have that other route?
private void button_tienda1_Click(object sender, EventArgs e)
{
label_boton_pulsado.Text = "Se ha seleccionado Adidas";
drawLine = true;
pictureBox1.Invalidate();
}
bool drawLine = false;
private void button_tienda2_Click(object sender, EventArgs e)
{
label_boton_pulsado.Text = "Se ha seleccionado Apple";
drawLine_apple = true;
pictureBox1.Invalidate();
}
bool drawLine_apple = false;
private void pictureBox1_Paint(object sender, PaintEventArgs e)
{
if (drawLine)
{
Graphics g = e.Graphics;
//Configuration of the pencil
Pen greenPen = new Pen(Color.FromArgb(255, 0, 255, 0), 5);
//Draw
g.DrawLine(greenPen, 220, 370, 220, 290);
/////
///Ruta Adidas
/////
//Dibujamos la linea de entrada al C.C
g.DrawLine(greenPen, 220, 290, 110, 290);
g.DrawLine(greenPen, 110, 290, 110, 310);
}
if (drawLine_apple)
{
Graphics g = e.Graphics;
//Configuration of the pencil
Pen greenPen = new Pen(Color.FromArgb(255, 0, 255, 0), 5);
//Draw
g.DrawLine(greenPen, 10, 10, 220, 290);
}
}

Viorel 122.6K Reputation points

2022-11-23T20:46:41.867+00:00

To remove the line, execute

drawLine = false; pictureBox1.Invalidate();

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Draw a line when you click a botton

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