click button event problem

Mike,

I went on to create a bit more complicated example. It works, but for some reason in the middle of debuggin it throws out this Parameter is not valid exception and I just have no idea why. could you take a look at it? The problem is in Program.cs for some reason with the problematic line being   Application.Run(new Form1());
   
Below is Form1.cs

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;

namespace Example1_2
{
    public partial class Form1 : Form
    {
        //Define the drawing area
        private Rectangle PlotArea;
        //Unit defined in world coordinate system:
        private float xMin = 0f;
        private float xMax = 10f;
        private float yMin = 0f;
        private float yMax = 10f;

        //Define the offset in pixel:
        private int offset = 30;

        private bool m_bPressed;
        public Form1()
        {
            InitializeComponent();
            this.SetStyle(ControlStyles.ResizeRedraw, true);
            this.BackColor = Color.White;
        }

        protected override void OnPaint(PaintEventArgs e)
        {
            Graphics g = e.Graphics;

            //Calculate the location and size of the drawing area
            //within which we want to draw the graphics:
            Rectangle rect = ClientRectangle;
            PlotArea = new Rectangle(rect.Location, rect.Size);
            PlotArea.Inflate(-offset, -offset);
            //Draw ClientRectangle and PlotArea using Pen:
            g.DrawRectangle(Pens.Red, rect);
            g.DrawRectangle(Pens.Black, PlotArea);

            if (m_bPressed)
            {
                //draw a line from point (3,2) to point (6,7)
                //using a pen with a width of 3 pixels:
                Pen aPen = new Pen(Color.Green, 3);
                g.DrawLine(aPen, Point2D(new PointF(3, 2)), Point2D(new PointF(6, 7)));
                aPen.Dispose();
                g.Dispose();
            }

        }

        private PointF Point2D(PointF ptf)
        {
        PointF aPoint = new PointF();
        aPoint.X=PlotArea.X +(ptf.X-xMin)*
        PlotArea.Width/(xMax - xMin);
        aPoint.Y=PlotArea.Bottom-(ptf.Y-yMin)*
        PlotArea.Height/(yMax-yMin);
        return aPoint;
        }

        private void Form1_Load(object sender, EventArgs e)
        {

        }

        private void toolStripButton1_Click(object sender, EventArgs e)
        {
            m_bPressed = true;
            Invalidate();
        }
    }
}

 
Hi Jonas,
glad it worked for you finally.  Your solution is correct.
-Mike

so I bastardized your code a bit and got mine working

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;

namespace Example1_1
{
    public partial class Form1 : Form
    {
        private bool m_bPressed;
        public Form1()
        {
            InitializeComponent();
            this.SetStyle(ControlStyles.ResizeRedraw, true);
            this.BackColor = Color.White;
        }

        private void Form1_Load(object sender, EventArgs e)
        {

        }

        protected override void OnPaint(PaintEventArgs e)
        {
            if (m_bPressed)
            {
                Graphics g = e.Graphics;
                g.PageUnit = GraphicsUnit.Inch;
                Pen blackPen = new Pen(Color.Black, 4 / g.DpiX);
                g.DrawLine(blackPen, 0, 0, 1, 1);
            }
        }

        private void button1_Click(object sender, EventArgs e)
        {
            m_bPressed = true;
            Invalidate();
        }
    }
}

I am afraid not working for me. First and foremost, there is no button generated, should I create button myself?

Then I deleted everything from public partial class Form1 : Form

down and paste your code, I am getting compilation error
Error    1    'Example1_13.Form1' does not contain a definition for 'Form1_Load' and no extension method 'Form1_Load' accepting a first argument of type 'Example1_13.Form1' could be found (are you missing a using directive or an assembly reference?)    c:\documents and settings\jonas\my documents\visual studio 2010\Projects\Example1_13\Example1_13\Form1.Designer.cs    40    55    Example1_13

this paqrticularly I don;t understand as my Form1 : Form didn;t change names, why wouldn;t it find it all of a sudden?..



Hi Jonas,
I omitted nothing obvious, this code was pasted from an app I made specifically to illustrate how to do this.  I ran the code before I sent it to you, so I know it works.  It draws a red line from the upper left hand corner of the screen to the bottom after you press the button.  I did not, however, paste the whole project, but I'll list the steps to recreate it.
1.  Go to New Projects and choose window forms application
2.  REplace the Form class generated with the class I sent you above.
3. compile and run
4.  press the button
5.  see the diagnol red line appear from upper left to bottom right corner of the form

thanks. you clearly omitted something probably very obvious because the code above in VS2010 gives a window but no line pops up when I click the buttin

You do not ever want to call the OnPaint event directly  like you did.  What you need to do is handle all your drawing in the paint event handler, but set a flag to indicate that you want the drawing to take place.  When do you set the flag?  set the flag in the button event handler, then invalidate the form to force the paint event handler to fire

namespace LineOnButtonPress { public partial class Form1 : Form { private bool m_bPressed; public Form1() { InitializeComponent(); } private void Form1_Paint(object sender, PaintEventArgs e) { if (m_bPressed) { e.Graphics.DrawLine(Pens.Red, 0,0, ClientRectangle.Width, ClientRectangle.Height); } } private void button1_Click(object sender, EventArgs e) { m_bPressed = true; Invalidate(); } } }