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POC# / Windows Forms: form's paint code not being executed
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  1. POC# / Windows Forms: form's paint code not being executed
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    copied!<p>I posted a similar but less specific question a couple hours ago, but the circumstances have changed. I'm working on a program that transforms graphics, presenting them in a panel in the upper left of the form. It was painting fine earlier, but now isn't and I can't undo, load old version, etc. Previously, the app was unresponsive even to events in the menus, as well as painting. I started a new project and got it up and running, the menus work and I brought over the buttons and stuff. But it still won't paint the axes and gridlines in the panel. I put breakpoints in both the main forms's paint handler and the splitContainer2_Panel1_Paint handler that should be doing the work, but the code here isn't even being executed. I have a timer that's active and invalidating the whole form every 100 ms, so why would the paint event handler not be called? Help?</p> <pre><code>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; using System.IO; namespace TransformerA { public partial class Transformer : Form { /* Initialize parameters */ private bool drawAxes = true; private bool drawGrid = true; private List&lt;ObjectSettings&gt; dispObjects = new List&lt;ObjectSettings&gt;(); /* Initialize form */ public Transformer() { InitializeComponent(); } private void Transformer_Load(object sender, EventArgs e) { // Populate available objects listbox string currentDir = Directory.GetCurrentDirectory(); string[] fileEntries = Directory.GetFiles(currentDir + @"\Objects"); foreach (string s in fileEntries) { int start = s.LastIndexOf(@"\"); int end = s.LastIndexOf(@"."); availObjectsListBox.Items.Add(s.Substring(start + 1, end - start - 1)); } // end foreach } /* Paint graphics */ // Paint main form private void Transformer_Paint(object sender, PaintEventArgs e) { splitContainer2_Panel1_Paint(sender, e); } // Paint graphics panel private void splitContainer2_Panel1_Paint(object sender, PaintEventArgs e) { Rectangle r = splitContainer2.Panel1.ClientRectangle; //Graphics g = splitContainer2.Panel1.CreateGraphics(); Graphics g = e.Graphics; Pen axisPen = new Pen(Color.Gray, 2.0f); Pen gridPen = new Pen(Color.Gray, 1.0f); g.Clear(Color.Blue); if (drawAxes) { g.DrawLine(axisPen, r.Left + 0.5f * r.Width, r.Top, r.Left + 0.5f * r.Width, r.Bottom); g.DrawLine(axisPen, r.Left, r.Top + 0.5f * r.Height, r.Right, r.Top + 0.5f * r.Height); } if (drawGrid) { // Vertical lines int xVal = 0; int xCenter = r.Width / 2; g.DrawLine(gridPen, xCenter, r.Top, xCenter, r.Bottom); for (int i = 0; i &lt; 10; i++) { xVal += r.Width / 20; g.DrawLine(gridPen, xCenter + xVal, r.Top, xCenter + xVal, r.Bottom); g.DrawLine(gridPen, xCenter - xVal, r.Top, xCenter - xVal, r.Bottom); } // Horizontal lines int yVal = 0; int yCenter = r.Height / 2; g.DrawLine(gridPen, r.Left, yCenter, r.Right, yCenter); for (int i = 0; i &lt; 10; i++) { yVal += r.Height / 20; g.DrawLine(gridPen, r.Left, yCenter + yVal, r.Right, yCenter + yVal); g.DrawLine(gridPen, r.Left, yCenter - yVal, r.Right, yCenter - yVal); } } // foreach object in displayed objects // keep list of displayed objects and their settings (make struct) g.Dispose(); axisPen.Dispose(); gridPen.Dispose(); } /* File menu */ private void saveImageToolStripMenuItem_Click(object sender, EventArgs e) { } private void exitToolStripMenuItem_Click(object sender, EventArgs e) { Close(); } /* Options menu */ private void axesOnoffToolStripMenuItem_Click(object sender, EventArgs e) { if (drawAxes == true) drawAxes = false; else drawAxes = true; } private void gridOnoffToolStripMenuItem_Click(object sender, EventArgs e) { if (drawGrid == true) drawGrid = false; else drawGrid = true; } /* Help menu */ private void helpToolStripMenuItem_Click(object sender, EventArgs e) { AboutBox dlg = new AboutBox(); dlg.ShowDialog(); } /* Other */ private void timer1_Tick(object sender, EventArgs e) { Invalidate(); } } } </code></pre>
 

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