I was told to make my forum post an article to know if you (the community) have
any better ideas in implementing the following:
To use the focus event of Textbox controls to set the Textbox Backgroundcolor
using the Enter() and the Leave() events. I even implemented an Error color
advise.
The normal backgroud color of the TextBox control is System.Drawing.Color.White,
the focused color is System.Drawing.Color.Yellow and the error sign color is
System.Drawing.Color.Red.
The implemented function is called by every Textbox control when occuring Enter
and Leave events and setting the appropriate color. Then a Button1 event
simulates an error (e.s.: invalid value, unknown username, text not found, etc.)
and focuses on textBox1.
The Button2 Click-Event simulates to pass a non textbox object to the
TextBox_Enter (Enter event in tetxBox1). This 2nd button (Button2) is to
demonstrate how to avoid passing wrong objects to a function (in this case an
error will be thrown if you try to pass any other objects than a textbox
object).
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
tboxfocus
{
public partial class Form1 :
Form
{
private System.Drawing.Color
m_tbcolorenter = System.Drawing.Color.Yellow;
private System.Drawing.Color
m_tbcolorleave = System.Drawing.Color.White;
private System.Drawing.Color
m_tbcolorerror = System.Drawing.Color.Red;
private
Boolean m_tbcolorerrorflag = false;
private void
ThrowErrormessage(object sender)
{
if (sender !=
null)
MessageBox.Show(String.Concat("Invalid
object: ", sender.ToString(),
", Only Textbox objects are
allowed!"), "Error - invalid object!");
else
MessageBox.Show("Unknown
error", "Sorry :=(");
}
public Form1()
{
InitializeComponent();
}
private void
textBox1_TextChanged(object sender,
EventArgs e)
{
}
private void
textBox2_TextChanged(object sender,
EventArgs e)
{
}
private void
Form1_Load(object sender,
EventArgs e)
{
}
private void
TextBox_Enter(object sender,
EventArgs e)
{
TextBox tb =
null;
if (sender
is TextBox)
{
tb = (TextBox)sender;
if (m_tbcolorerrorflag)
tb.BackColor = m_tbcolorerror;
else
tb.BackColor = m_tbcolorenter;
}
else ThrowErrormessage(sender);
return;
}
private void
TextBox_Leave(object sender,
EventArgs e)
{
TextBox tb =
null;
if (sender
is TextBox)
{
tb = (TextBox)sender;
tb.BackColor = m_tbcolorleave;
}
else ThrowErrormessage(sender);
return;
}
private void
TextBox_Error(object sender,
EventArgs e)
{
TextBox tb =
null;
if (sender
is TextBox)
{
tb = (TextBox)sender;
tb.BackColor = m_tbcolorerror;
tb.Focus();
m_tbcolorerrorflag = false;
}
else ThrowErrormessage(sender);
return;
}
private void
button1_Click(object sender,
EventArgs e)
{
m_tbcolorerrorflag = true;
TextBox_Error(textBox1, e);
}
private void
button2_Click(object sender,
EventArgs e)
{
TextBox_Enter(button2, e);
}
}
}
If you have any better or additional suggestions I'm glad to it… :=) Good work
and code it right!