Autowidth of ComboBox's content

Auto-width of ComboBox's content

回答1

You can't use it directly.

Do a trick

First iterate through all items of your combobox, check for the width of every items by assigning the text to a label. Then, check width every time, if width of current item gets greater than previous items then change the maximum width.

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);
}

---

OR

As suggested by stakx, you can use TextRenderer class

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;
}

回答2

obj.ToString() doesn't work for me, I suggest to use myCombo.GetItemText(obj). This works for me:

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;
}

自己处理的，综合上面两个

 private void SetComboBoxWidth(ComboBox comboBox)
        {
            int maxWidth = 260;
            foreach (var obj in comboBox.Items)
            {
                var temp = TextRenderer.MeasureText(comboBox.GetItemText(obj), comboBox.Font).Width;
                if (temp > maxWidth)
                {
                    maxWidth = temp;
                }
            }

            comboBox.Width = maxWidth + SystemInformation.VerticalScrollBarWidth;
        }