C# 组合框的宽度也一样，单击下拉列表后，看到宽度发生变化时，它看起来很奇怪。因为我将组合框动态添加到FlowLayoutPanel中，所以我订阅了ParentChanged事件，它看起来好多了。捕捉得不错myCombo.GetItemText（obj）肯定比其

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组合框的宽度也一样，单击下拉列表后，看到宽度发生变化时，它看起来很奇怪。因为我将组合框动态添加到FlowLayoutPanel中，所以我订阅了ParentChanged事件，它看起来好多了。捕捉得不错

myCombo.GetItemText（obj）

肯定比其他答案更正确

obj.ToString（）

可以不同于组合框的

DisplayMember

属性。首先，问题是要求自动调整大小，这与显式设置宽度正好相反。但是第二，你在这里的意思还不清楚。什么是密码箱？您谈论的是什么

ItemWidth

属性？什么也没找到。

int DropDownWidth(ComboBox myCombo)
{
    int maxWidth = 0;
    int temp = 0;
    Label label1 = new Label();

    foreach (var obj in myCombo.Items)
    {
        label1.Text = obj.ToString();
        temp = label1.PreferredWidth;
        if (temp > maxWidth)
        {
            maxWidth = temp;
        }
    }
    label1.Dispose();
    return maxWidth;           
}

private void Form1_Load(object sender, EventArgs e)
{
    comboBox1.DropDownWidth = DropDownWidth(comboBox1);
}

int DropDownWidth(ComboBox myCombo)
{
    int maxWidth = 0, temp = 0;
    foreach (var obj in myCombo.Items)
    {
        temp = TextRenderer.MeasureText(obj.ToString(), myCombo.Font).Width;
        if (temp > maxWidth)
        {
            maxWidth = temp;
        }
    }
    return maxWidth;
}

 private void AdjustWidthComboBox_DropDown(object sender, EventArgs e)
        {
            var 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;

            var itemsList = senderComboBox.Items.Cast<object>().Select(item => item.ToString());

            foreach (string s in itemsList)
            {
                int newWidth = (int)g.MeasureString(s, font).Width + vertScrollBarWidth;

                if (width < newWidth)
                {
                    width = newWidth;
                }
            }

            senderComboBox.DropDownWidth = width;
        }

int setWidth_comboBox(ComboBox cb)
{
  int maxWidth = 0, temp = 0;
  foreach (string s in cb.Items)
  {
    temp = TextRenderer.MeasureText(s, cb.Font).Width;
    if (temp > maxWidth)
    {
      maxWidth = temp;
    }
  }
  return maxWidth + SystemInformation.VerticalScrollBarWidth;
}

myComboBox.Width = setWidth_comboBox(myComboBox);

private int DropDownWidth(ComboBox myCombo)
{
    int maxWidth = 0, temp = 0;
    foreach (var obj in myCombo.Items)
    {
        temp = TextRenderer.MeasureText(myCombo.GetItemText(obj), myCombo.Font).Width;
        if (temp > maxWidth)
        {
            maxWidth = temp;
        }
    }
    return maxWidth + SystemInformation.VerticalScrollBarWidth;
}

    public static int AutoDropDownWidth(this ComboBox myCombo)
    {
        return AutoDropDownWidth<object>(myCombo, o => o.ToString());
    }
    public static int AutoDropDownWidth<T>(this ComboBox myCombo, Func<T, string> description)
    {
        int maxWidth = 1;
        int temp = 1;
        int vertScrollBarWidth = (myCombo.Items.Count > myCombo.MaxDropDownItems)
                ? SystemInformation.VerticalScrollBarWidth : 0;

        foreach (T obj in myCombo.Items)
        {
            if (obj is T)
            {
                T t = (T)obj;
                temp = TextRenderer.MeasureText(description(t), myCombo.Font).Width;
                if (temp > maxWidth)
                {
                    maxWidth = temp;
                }
            }

        }
        return maxWidth + vertScrollBarWidth;
    }

public class Person
{
    public string FullName {get;set;}
}

cbPeople.DropDownWidth = cbPeople.AutoDropDownWidth<Person>(p => p.FullName);

private void combo_DropDown(object sender, EventArgs e)
{
    //http://www.codeproject.com/Articles/5801/Adjust-combo-box-drop-down-list-width-to-longest-s
    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 (string s in ((ComboBox)sender).Items)
    {
        newWidth = (int)g.MeasureString(s, font).Width
            + vertScrollBarWidth;
        if (width < newWidth)
        {
            width = newWidth;
        }

        if (senderComboBox.Width < newWidth)
        {
            senderComboBox.Width = newWidth+ SystemInformation.VerticalScrollBarWidth;
        }
    }
    senderComboBox.DropDownWidth = width;
}

private int GetDropDownWidth(ComboBox combo)
{
    object[] items = new object[combo.Items.Count];
    combo.Items.CopyTo(items, 0);
    return items.Select(obj => TextRenderer.MeasureText(combo.GetItemText(obj), combo.Font).Width).Max();
}

   private int AutoSizeDropDownWidth(ComboBox comboBox)
        {
            var width = cmboxUnit.DropDownWidth;
            var g = cmboxUnit.CreateGraphics();
            var font = cmboxUnit.Font;

            var verticalScrollBarWidth = cmboxUnit.Items.Count > cmboxUnit.MaxDropDownItems
                ? SystemInformation.VerticalScrollBarWidth : 0;

            var itemsList = cmboxUnit.Items.Cast<object>().Select(item => item);

            foreach (DataRowView dr in itemsList)
            {
                int newWidth = (int)g.MeasureString(dr["Name"].ToString(), font).Width + verticalScrollBarWidth;

                if (width < newWidth)
                {
                    width = newWidth;
                }
            }
            return width;
        }