asked on

GDI Drawing Lines triggered off a button click.

I have no problem with the following code:

/***************************
      protected override void OnPaint(PaintEventArgs pe)
      {
            Graphics g = pe.Graphics ;
            Pen L1Pen = new Pen(Color.Red);
            Point L1x = new Point(100, 800);
            Point L1y = new Point(275, 800);

            Pen L2Pen = new Pen(Color.Blue);
            Point L2x = new Point(275, 800);
            Point L2y = new Point(625, 800);

            Pen L3Pen = new Pen(Color.Orange);
            Point L3x = new Point(625, 800);
            Point L3y = new Point(775, 800);

            Pen L4Pen = new Pen(Color.Black);
            Point L4x = new Point(775, 800);
            Point L4y = new Point(950, 800);



            g.DrawLine(L1Pen, L1x, L1y);
            g.DrawLine(L2Pen, L2x, L2y);
            g.DrawLine(L3Pen, L3x, L3y);
            g.DrawLine(L4Pen, L4x, L4y);
      }

***************/

However when I attempt to build the following code to trigger it in a off a button click I receive the following build error: The type or namespace name 'pe' could not be found (are you missing a using directive or an assembly reference?)
.

For example:
/*******************************
private void button1_Click(object sender, System.EventArgs e)
      {
            Graphics g = pe.Graphics ;
            Pen L1Pen = new Pen(Color.Red);
            Point L1x = new Point(100, 800);
            Point L1y = new Point(275, 800);

            Pen L2Pen = new Pen(Color.Blue);
            Point L2x = new Point(275, 800);
            Point L2y = new Point(625, 800);

            Pen L3Pen = new Pen(Color.Orange);
            Point L3x = new Point(625, 800);
            Point L3y = new Point(775, 800);

            Pen L4Pen = new Pen(Color.Black);
            Point L4x = new Point(775, 800);
            Point L4y = new Point(950, 800);



            g.DrawLine(L1Pen, L1x, L1y);
            g.DrawLine(L2Pen, L2x, L2y);
            g.DrawLine(L3Pen, L3x, L3y);
            g.DrawLine(L4Pen, L4x, L4y);
}

**************/

ASKER CERTIFIED SOLUTION

millsoft

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int200

ASKER

Thanks for the response, but I just put in your code and can not see any graphics drawn on the window. I created a simple C# Windows App, created a button to the form and added your code.
Here is the entire code:

using System;
using System.Drawing;
using System.Collections;
using System.ComponentModel;
using System.Windows.Forms;
using System.Data;

namespace GDITest2
{
      /// <summary>
      /// Summary description for Form1.
      /// </summary>
      public class Form1 : System.Windows.Forms.Form
      {
            private System.Windows.Forms.Button button1;
            /// <summary>
            /// Required designer variable.
            /// </summary>
            private System.ComponentModel.Container components = null;

            public Form1()
            {
                  //
                  // Required for Windows Form Designer support
                  //
                  InitializeComponent();

                  //
                  // TODO: Add any constructor code after InitializeComponent call
                  //
            }

            /// <summary>
            /// Clean up any resources being used.
            /// </summary>
            protected override void Dispose( bool disposing )
            {
                  if( disposing )
                  {
                        if (components != null)
                        {
                              components.Dispose();
                        }
                  }
                  base.Dispose( disposing );
            }

            #region Windows Form Designer generated code
            /// <summary>
            /// Required method for Designer support - do not modify
            /// the contents of this method with the code editor.
            /// </summary>
            private void InitializeComponent()
            {
                  this.button1 = new System.Windows.Forms.Button();
                  this.SuspendLayout();
                  //
                  // button1
                  //
                  this.button1.Location = new System.Drawing.Point(72, 64);
                  this.button1.Name = "button1";
                  this.button1.Size = new System.Drawing.Size(96, 32);
                  this.button1.TabIndex = 0;
                  this.button1.Text = "button1";
                  //
                  // Form1
                  //
                  this.AutoScaleBaseSize = new System.Drawing.Size(5, 13);
                  this.ClientSize = new System.Drawing.Size(292, 266);
                  this.Controls.Add(this.button1);
                  this.Name = "Form1";
                  this.Text = "Form1";
                  this.ResumeLayout(false);

            }
            #endregion


            private void PaintMe( Graphics g )
            {
                  Pen L1Pen = new Pen(Color.Red);
                  Point L1x = new Point(100, 1000);
                  Point L1y = new Point(100, 825);

                  Pen L2Pen = new Pen(Color.Blue);
                  Point L2x = new Point(100, 825);
                  Point L2y = new Point(100, 475);

                  Pen L3Pen = new Pen(Color.Orange);
                  Point L3x = new Point(100, 475);
                  Point L3y = new Point(100, 325);

                  Pen L4Pen = new Pen(Color.Black);
                  Point L4x = new Point(100, 325);
                  Point L4y = new Point(275, 325);

                  g.DrawLine(L1Pen, L1x, L1y);
                  g.DrawLine(L2Pen, L2x, L2y);
                  g.DrawLine(L3Pen, L3x, L3y);
                  g.DrawLine(L4Pen, L4x, L4y);
            }

            private void button1_Click(object sender, System.EventArgs e)
            {
                  System.Windows.Forms.Button b = (System.Windows.Forms.Button) sender;
                  PaintMe( b.Parent.CreateGraphics() );
            }

            /// <summary>
            /// The main entry point for the application.
            /// </summary>
            [STAThread]
            static void Main()
            {
                  Application.Run(new Form1());
            }
      }
}

Thanks

millsoft

There are two possibilites.

First, it doesn't appear the button has a event handler wired up.

You need something like
this.button1.click += new ....

I'm not at my C# machine so I don't have the exact syntax handy.

Second, the Y coordinate you are using (825) is probably off the bottom of the window. That is why I used 80 instead for testing purposes.

int200

ASKER

Hi Brad,

You were correct, I didn't double click on the button from the form which auto-generates the handler. I just added the button and put the code in.

It works fine now. Thanks! By the way, I'm running 1600x1200 so that's why I'm using such large values.

Now, I need to look into how to pass variables a the points so I can use one function I can pass the x and y coorinates to.

Thanks and Best Regards!