Question

How can I set the background color of a specific item in a System.Windows.Forms.ListBox? I would like to be able to set multiple ones if possible.

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Solution

Probably the only way to accomplish that is to draw the items yourself.

Set the DrawMode to OwnerDrawFixed

and code something like this on the DrawItem event:

private void listBox_DrawItem(object sender, DrawItemEventArgs e)
{
    e.DrawBackground();
    Graphics g = e.Graphics;

    g.FillRectangle(new SolidBrush(Color.Silver), e.Bounds);

    // Print text

    e.DrawFocusRectangle();
}

Second option would be using a ListView, although they have an other way of implementations (not really data bound, but more flexible in way of columns)

OTHER TIPS

Thanks for the answer by Grad van Horck, it guided me in the correct direction.

To support text (not just background color) here is my fully working code:

//global brushes with ordinary/selected colors
private SolidBrush reportsForegroundBrushSelected = new SolidBrush(Color.White);
private SolidBrush reportsForegroundBrush = new SolidBrush(Color.Black);
private SolidBrush reportsBackgroundBrushSelected = new SolidBrush(Color.FromKnownColor(KnownColor.Highlight));
private SolidBrush reportsBackgroundBrush1 = new SolidBrush(Color.White);
private SolidBrush reportsBackgroundBrush2 = new SolidBrush(Color.Gray);

//custom method to draw the items, don't forget to set DrawMode of the ListBox to OwnerDrawFixed
private void lbReports_DrawItem(object sender, DrawItemEventArgs e)
{
    e.DrawBackground();
    bool selected = ((e.State & DrawItemState.Selected) == DrawItemState.Selected);

    int index = e.Index;
    if (index >= 0 && index < lbReports.Items.Count)
    {
        string text = lbReports.Items[index].ToString();
        Graphics g = e.Graphics;

        //background:
        SolidBrush backgroundBrush;
        if (selected)
            backgroundBrush = reportsBackgroundBrushSelected;
        else if ((index % 2) == 0)
            backgroundBrush = reportsBackgroundBrush1;
        else
            backgroundBrush = reportsBackgroundBrush2;
        g.FillRectangle(backgroundBrush, e.Bounds);

        //text:
        SolidBrush foregroundBrush = (selected) ? reportsForegroundBrushSelected : reportsForegroundBrush;
        g.DrawString(text, e.Font, foregroundBrush, lbReports.GetItemRectangle(index).Location);
    }

    e.DrawFocusRectangle();
}

The above adds to the given code and will show the proper text plus highlight selected item.

// Set the background to a predefined colour
MyListBox.BackColor = Color.Red;
// OR: Set parts of a color.
MyListBox.BackColor.R = 255;
MyListBox.BackColor.G = 0;
MyListBox.BackColor.B = 0;

If what you mean by setting multiple background colors is setting a different background color for each item, this isn't possible with a ListBox, but IS with a ListView, with something like:

// Set the background of the first item in the list
MyListView.Items[0].BackColor = Color.Red;
public MainForm()
{
    InitializeComponent();
    this.listbox1.DrawItem += new DrawItemEventHandler(this.listbox1_DrawItem);
}

private void listbox1_DrawItem(object sender, System.Windows.Forms.DrawItemEventArgs e)
{
    e.DrawBackground();
    Brush myBrush = Brushes.Black;
    var item = listbox1.Items[e.Index];
    if(e.Index % 2 == 0)
    {
        e.Graphics.FillRectangle(new SolidBrush(Color.Gold), e.Bounds);
    }
        e.Graphics.DrawString(((ListBox)sender).Items[e.Index].ToString(), 
            e.Font, myBrush,e.Bounds, StringFormat.GenericDefault);
        e.DrawFocusRectangle();
    }
}
public Picker()
{
    InitializeComponent();
    this.listBox.DrawMode = DrawMode.OwnerDrawVariable;
    this.listBox.MeasureItem += listBoxMetals_MeasureItem;
    this.listBox.DrawItem += listBoxMetals_DrawItem;
}

void listBoxMetals_DrawItem(object sender, DrawItemEventArgs e)
{
    e.DrawBackground();
    Brush myBrush = Brushes.Black;
    var item = listBox.Items[e.Index] as Mapping;
    if (e.Index % 2 == 0)
    {
        e.Graphics.FillRectangle(new SolidBrush(Color.GhostWhite), e.Bounds);
    }
    e.Graphics.DrawString(item.Name,
        e.Font, myBrush, e.Bounds, StringFormat.GenericDefault);
    e.DrawFocusRectangle();
}

Complete sample

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