Right justified combobox in C#

问题

By default the items in the C# Combobox are left aligned. Are there any options available to change this justification apart from overriding DrawItem method and setting the combobox drawmode --> DrawMode.OwnerDrawFixed?

Cheers

回答1:

You could just set the control style to RightToLeft = RightToLeft.Yes if you don't mind the drop widget on the other side as well.

or

set DrawMode = OwnerDrawFixed; and hook the DrawItem event, then something like

    private void comboBox1_DrawItem(object sender, DrawItemEventArgs e)
    {
        if (e.Index == -1)
            return;
        ComboBox combo = ((ComboBox) sender);
        using (SolidBrush brush = new SolidBrush(e.ForeColor))
        {
            e.DrawBackground();
            e.Graphics.DrawString(combo.Items[e.Index].ToString(), e.Font, brush, e.Bounds, new StringFormat(StringFormatFlags.DirectionRightToLeft));
            e.DrawFocusRectangle();
        }
    }

回答2:

In WPF this would be as easy as specifying an ItemContainerStyle. In Windows Forms it's a little trickier. Without custom drawing, you could set the RightToLeft property on the ComboBox but this would unfortunately also affect the drop down button.

Since Windows Forms uses a native ComboBox, and Windows doesn't have a ComboBox style like ES_RIGHT that affects the text alignment, I think your only option is to resort to owner draw. It would probably be a good idea to derive a class from ComboBox and add a TextAlignment property or something. Then you would only apply your drawing if TextAlignment was centered or right aligned.

回答3:

You must "DrawMode = System.Windows.Forms.DrawMode.OwnerDrawFixed" and your own draw method like this.

protected virtual void OnDrawItem(object sender, DrawItemEventArgs e)
{
    var comboBox = sender as ComboBox;

    if (comboBox == null)
    {
        return;
    }

    e.DrawBackground();

    if (e.Index >= 0)
    {
        StringFormat sf = new StringFormat();
        sf.LineAlignment = StringAlignment.Center;
        sf.Alignment = StringAlignment.Center;

        Brush brush = new SolidBrush(comboBox.ForeColor);

        if ((e.State & DrawItemState.Selected) == DrawItemState.Selected)
        {
            brush = SystemBrushes.HighlightText;
        }

        e.Graphics.DrawString(comboBox.Items[e.Index].ToString(), comboBox.Font, brush, e.Bounds, sf);
    }
}

来源：https://stackoverflow.com/questions/3099133/right-justified-combobox-in-c-sharp