DataGridView / ComboBox need two display states (long and short) for information

Question

I've got a DataGidView that's very tight on horizontal space, and a column that has rather lengthy descriptions.

What I'd like to do is create a ComboBox column that:

1. Displays a shortened version of the description
2. Has the full description in the drop-down
3. Behind the scenes deals with the actual value

So for example, I have this contrived example below. The real list can have 20-30 items with text that's quite lengthy:

Code    Short      DropDown Text
 1      BigBox     Boxes larger than 6' x 6'
 2      SmBox      Boxes smaller than 6' x 6'
 3      BigBrl     Barrel 55 gallons
 4      SmBrl      Barrel less than 55 gallons

So what I want to show is:

When I open the dropdown I want to see:

And of course, when I query the value for the cell, I want "1".

I could split hairs and make the "short" description the first part of the longer description ("BigBx Boxes larger than 6' x 6'") but that doesn't seem right.

I'm looking for suggestions on the best way to accomplish this. No code yet to show, since I'm not quite sure where to start.

Answer 1

You'll want to change the DisplayMember of the combobox on the events DropDown and DropDownClosed.

On the Event DropDown, You'll want to change the DisplayMember to your Long Name. One thing I discovered is that changing the DisplayMember resets the SelectedIndex, so you'll want to save that and then reset it after you've changed the display.

int i = comboBox1.SelectedIndex;
comboBox1.DisplayMember = "LongNm";
comboBox1.SelectedIndex = i;

You'll want to repeat this process with the DropDownClosed event and the Short Name to return to your closed display.

int i = comboBox1.SelectedIndex;
comboBox1.DisplayMember = "ShortNm";
comboBox1.SelectedIndex = i;

The last problem I encountered was changing the width of the combobox dropdown. I found code to do that here. The final code I had looks like this:

public partial class Form1 : Form
{
    List<ComboData> data;
    public Form1()
    {
        InitializeComponent();
    }

    private void Form1_Load(object sender, EventArgs e)
    {
        data = new List<ComboData>();
        data.Add(new ComboData(1, "BigBox", "Boxes larger than 6x6"));
        data.Add(new ComboData(2, "SmBox", "Boxes small than 6x6"));
        data.Add(new ComboData(3, "BirBrl", "Barrel 55 Gallons"));
        data.Add(new ComboData(4, "smBrl", "Barrel less than 55 gallons"));

        comboBox1.DataSource = data;
        comboBox1.DisplayMember = "ShortNm";
    }

    private void comboBox1_DropDown(object sender, EventArgs e)
    {
        int i = comboBox1.SelectedIndex;
        comboBox1.DisplayMember = "LongNm";
        comboBox1.SelectedIndex = i;


        ComboBox senderComboBox = (ComboBox)sender;
        int width = senderComboBox.DropDownWidth;
        Graphics g = senderComboBox.CreateGraphics();
        Font font = senderComboBox.Font;
        int vertScrollBarWidth =
            (senderComboBox.Items.Count > senderComboBox.MaxDropDownItems)
            ? SystemInformation.VerticalScrollBarWidth : 0;

        int newWidth;
        foreach (ComboData s in ((ComboBox)sender).Items)
        {
            newWidth = (int)g.MeasureString(s.LongNm, font).Width
                + vertScrollBarWidth;
            if (width < newWidth)
            {
                width = newWidth;
            }
        }
        senderComboBox.DropDownWidth = width;
    }

    private void comboBox1_DropDownClosed(object sender, EventArgs e)
    {
        int i = comboBox1.SelectedIndex;
        comboBox1.DisplayMember = "ShortNm";
        comboBox1.SelectedIndex = i;
    }
}

public class ComboData
{
    public int Code;
    public string ShortNm
    {
        get;
        set;
    }
    public string LongNm
    {
        get;
        set;
    }

    public ComboData(int c, string s, string l)
    {
        Code = c;
        ShortNm = s;
        LongNm = l;
    }
}

The end result looks like this: