Library of Custom Controls in Winforms - winforms

Question

I wanted a TextBox with just digits as entry. So i wrote following code in the KeyPress events of the textbox
if(!char.IsDigit(e.KeyChar))
{
e.handled = true;
}
and it worked great. But I generally need them in many places of my application so then i wrote a partial class with following codes:
public partial class digitTextBox : TextBox
{
public digitTextBox()
{
this.KeyPress += new KeyPressEventHandler(digitTextBox_KeyPress);
}
void digitTextBox_KeyPress(object sender, KeyPressEventArgs e)
{
if (char.IsDigit(e.KeyChar))
{
e.Handled = true;
}
}
}
build my solution and I got a control in my toolbox and even this was working perfectly fine.
But i had many TextBoxes with some or the other specification like, some should not accept special characters, some should accept decimals, some with decimals up to 2 digits after point....and so on and i do need these kind of controls in many applications.
So I thought of writing a Library(.dll) of my custom controls and if possible even for there validations. Honestly speaking I don't have much idea about using libraries. So I made a library with 2 different kind of textboxes and created a .dll file out of them. Now I created a different winform application and I added reference of my custom control .dll file. But nothing happened.
So i just wanted to know what should be my approach in achieving it. Is there a better way to achieve these kind of tasks. and any new suggestions are also welcome. Thanks in advance.

Answer 1

Try right-mouse clicking the ToolBox and select "Choose Items..." and then select your controls from the available list. If you don't see them, then click on the Browse button and select your DLL.
On a side note, you might be able to combine your two textboxes by adding properties:
public class MyTextBox : TextBox
{
public bool AllowDigitsOnly { get; set; }
protected override void OnKeyPress(KeyPressEventArgs e)
{
if (this.AllowDigitsOnly)
{
if (!char.IsDigit(e.KeyChar))
e.Handled = true;
}
base.OnKeyPress(e);
}
}

Answer 2

I would suggest implementing a single custom control, which controls input based on a regular expression. Instead of limiting keypresses, I would prevent the control loosing focus if its text does not match the regular expression. Some change in background color or a popup ballon can be used to display errors and/or a description of what the input is supposed to be.

Answer 3

I did something similar and what helped me was to add properties to my textbox instead of creating 2 different types for integers and doubles (basically allowing a decimal for my requirements).
By creating a property, you can actually choose whether you want the textbox as integer or double in the Properties view at design-time. Just like how you have Font, ReadOnly etc that you set during design time.
Here is my code to make the properties,
/// <summary>
/// Identify textbox type as integer or double
/// </summary>
public enum numericID
{
Integer,
Double
};
/// <summary>
/// Textbox type property, default is integer
/// </summary>
private numericID numericType = numericID.Integer;
/// <summary>
/// Getter and setter for property
/// </summary>
[Browsable(true),
DisplayName("TextBoxType"),
DefaultValue(numericID.Integer),
Description("Indicates whether the textbox must only accept integers or doubles."),
Category("Behavior")]
public numericID NumericType
{
get { return numericType; }
set { numericType = value; }
}
and the onKeyPress event is actually quite handy from the msdn website. It handles all different types of characters for numerics and you can choose whichever one works best for you.