Question

我创建了一个自定义组合框，其中我可以在ComboBox下拉时显示多列项目和图像。现在我遇到的问题是当选择一个项目时，我需要完全按照下拉列表中显示的项目显示项目，即。那么我应该参加哪个活动？或者我怎样才能做到这一点？

到目前为止，我有这个

public partial class XComboBox : ComboBox
{
    private Int32 ColumnGap = 10;
    private Int32 firstColumnWidth;
    private Int32 secondColumnWidth;

    public XComboBox()
    {
        DrawMode = DrawMode.OwnerDrawFixed;
        firstColumnWidth = DropDownWidth / 2;
        secondColumnWidth = DropDownWidth / 2;
        AutoCompleteSource = System.Windows.Forms.AutoCompleteSource.ListItems;

    }

    public Boolean MultiColumn
    {
        get;
        set;
    }

    public String ColumnWidths
    {
        get
        {
            return String.Concat(firstColumnWidth.ToString(), ";", secondColumnWidth.ToString());
        }
        set
        {
            if (Regex.Match(value, "^[0-9]+;[0-9]+$").Success)
            {
                String[] widths = value.Split(';');
                firstColumnWidth = Int32.Parse(widths[0]);
                secondColumnWidth = Int32.Parse(widths[1]);
                DropDownWidth = (firstColumnWidth + secondColumnWidth + ColumnGap) > Width ? (firstColumnWidth + secondColumnWidth + ColumnGap) : Width;
            }
            else
            {
                throw new ArgumentException("Invalid argument specified. Value of ColumnWidths property should be in \"[0-9];[0-9]\" format");
            }
        }
    }

    protected override void OnDrawItem(DrawItemEventArgs e)
    {
        XComboItem item = (XComboItem)Items[e.Index];
        ColumnGap = firstColumnWidth == 0 ? 0 : ColumnGap;

        e.DrawBackground();
        e.DrawFocusRectangle();

        string first = item.DisplayName;
        string second = item.Description;

        if (MultiColumn)
        {
            while (TextRenderer.MeasureText(first, e.Font).Width > firstColumnWidth)
            {
                first = first.Substring(0, first.Length - 1);
            }

            e.Graphics.DrawString(first, e.Font, new SolidBrush(e.ForeColor), e.Bounds.Left, e.Bounds.Top);
            e.Graphics.DrawString(second, e.Font, new SolidBrush(e.ForeColor), e.Bounds.Left + firstColumnWidth + ColumnGap, e.Bounds.Top);
        }
        else
        {
            e.Graphics.DrawString(second, e.Font, new SolidBrush(e.ForeColor), e.Bounds.Left, e.Bounds.Top);
        }
    }

    protected override void OnMeasureItem(MeasureItemEventArgs e)
    {
        base.OnMeasureItem(e);
    }

    protected override void OnSelectedValueChanged(EventArgs e)
    {
        base.OnSelectedValueChanged(e);
    }
}   

public class XComboItem
{
    public Int32 ItemId { get; set; }
    public String DisplayName { get; set; }
    public Object Value { get; set; }
    public String Description { get; set; }

    public XComboItem()
    {
        DisplayName = String.Empty;
        Description = String.Empty;
        DisplayText = String.Empty;
    }

    internal String DisplayText
    {
        get;
        set;
    }

    public override string ToString()
    {
        return DisplayName;            
    }
}

Answer 1

我假设您不希望用户输入 - 给定格式。为此，您需要设置DropDownStyle == DropDownList。 ..并且您当前的代码应该可以正常工作。

为下拉和下方的编辑/文本框部分调用OnDrawItem。

如：https://stackoverflow.com/a/5111692/631687中所述，您可以区分正在呈现的内容。

ComboBox自定义显示

1 个答案: