How do I disable a custom combo box without being grayed?

Question

0.00/5 (No votes)

See more:

Hello, I have a custom combo box class.
In some cases I need it to be disabled without being grayed and in some others I need it to be enabled with loaded data of a data source of sql server database through a sql query.
So I thought about this, to go inside my custom class
and create a custom MouseMove event in order to make it loose focus when I want to disable it. But I don't know how to override it, because I have an additional argument of bool type the Disable.

C#

private void CustomCbo_MouseMove(object sender, MouseEventArgs e, bool Disable)
{
     if (Disable)
     {
         this.Parent.Focus();
         this.SelectionLength = 0;
     }
}

However I found on another site the following, it's ok, but I don't understand it very well and I need the oppossite too, in order to enable the
CustomCombo so that to have the appropriate values of datasource of my database.

C#

public void DisableComboWithoutGrayedOut()
    {
          //Appearence Enable, behavior Disabled
          this.DropDownHeight = 1;
          this.KeyDown += (s, e) => e.Handled = true;
          this.KeyPress += (s, e) => e.Handled = true;
          this.KeyUp += (s, e) => e.Handled = true;

     }

In case I use the Enabled property it's ok, but I don't like to be grayed out. And ComboBox doesn't have a ReadOnly property like textboxes.
Any suggestion and explanation for both ways please, will be much appreciated. Thank you so much in advanced.

What I have tried:

private void CustomCbo_MouseMove(object sender, MouseEventArgs e, bool Disable)
 {
      if (Disable)
      {
          this.Parent.Focus();
          this.SelectionLength = 0;
      }
 }

  public void DisableComboWithoutGrayedOut()
      {
            //Appearence Enable, behavior Disabled
            this.DropDownHeight = 1;
            this.KeyDown += (s, e) => e.Handled = true;
            this.KeyPress += (s, e) => e.Handled = true;
            this.KeyUp += (s, e) => e.Handled = true;
           
       }

Posted 11-Mar-24 5:19am

Aggeliki Asimakopoulou

Add a Solution

3 solutions

Solution 2

Here is my customCombo class

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.ComponentModel;
using System.Drawing;
namespace AngelTechShop
{
    public class CustomCombo : ComboBox
    {
        public CustomCombo()
        {
            BorderColor = Color.DimGray;
        }

        [Browsable(true)]
        [Category("Appearance")]
        [DefaultValue(typeof(Color), "DimGray")]
        public Color BorderColor { get; set; }

        private const int WM_PAINT = 0xF;
        private int buttonWidth = SystemInformation.HorizontalScrollBarArrowWidth;

        private bool mDisable;

        public bool Disable
        {
            get { return mDisable; }
            set { mDisable = value; }
        }
        protected override void WndProc(ref Message m)
        {
            base.WndProc(ref m);
            if (m.Msg == WM_PAINT)
            {
                using (var g = Graphics.FromHwnd(Handle))
                {
                    // Uncomment this if you don't want the "highlight border".

                    using (var p = new Pen(this.BorderColor, 1))
                    {
                        g.DrawRectangle(p, 0, 0, Width - 1, Height - 1);
                    }
                    using (var p = new Pen(this.BorderColor, 2))
                    {
                        g.DrawRectangle(p, 0, 0, Width, Height);
                    }
                }
            }
        }
        
    }
}

Posted 11-Mar-24 5:39am

Aggeliki Asimakopoulou

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

Mike Hankey · Accepted Answer · 2024-03-11T05:27:00

Solution 1

The object is that the ComboBox is not actually disable but the dropdown is set to 1 so that it drops down but since only 1 pixel you wont see it.

The other KeyDown, KeyPress and KeyUp handlers e.Handled properties are set to true meaning that the event has been handled and nothing more is done.

Posted 11-Mar-24 5:27am

Mike Hankey

Comments

Aggeliki Asimakopoulou 12-Mar-24 10:08am

The default DropDownHeight value is actually 106, but if we set it to 1, we can only retrieve it with a const variable. Thank you!!!

Mike Hankey · Accepted Answer · 2024-03-11T07:46:00

Create an enable method. By commenting out the KeyDown, KeyPress and KeyUp handlers they will function normally!

C#

public void EnableComboWithoutGrayedOut()
      {
            //Appearence Enable, behavior Enabled
            this.DropDownHeight = ??;  // Whatever it was before or what you want it to be
            //this.KeyDown += (s, e) => e.Handled = true;
            //this.KeyPress += (s, e) => e.Handled = true;
            //this.KeyUp += (s, e) => e.Handled = true;
           
       }