双缓冲客户绘制列表框

Question

我有一个自定义绘制方法，因此我可以将列表框中的项目设置为不同的颜色。问题是我每 500 毫秒重新绘制一次列表框以检查值是否已更改。这使列表框闪烁，我不知道如何双缓冲代码。有人可以帮忙吗？

private void listBox_DrawItem(object sender, DrawItemEventArgs e)
{
    ListBox sendingListBox = (ListBox)sender;

    CustomListBoxItem item = sendingListBox.Items[e.Index] as CustomListBoxItem; // Get the current item and cast it to MyListBoxItem

    if (item != null)
    {
         e.Graphics.DrawString( // Draw the appropriate text in the ListBox
            item.Message, // The message linked to the item
            zone1ListBox.Font, // Take the font from the listbox
            new SolidBrush(item.ItemColor), // Set the color 
            0, // X pixel coordinate
            e.Index * zone1ListBox.ItemHeight // Y pixel coordinate.  Multiply the index by the ItemHeight defined in the listbox.
         );
    }
    else
    {
        // The item isn't a MyListBoxItem, do something about it
    }
}

Answer 1

如果你需要启用ListBox的双缓冲你应该继承一个类，因为属性是private并设置它为true，或者使用SetStyle()方法并应用WS_EX_COMPOSITED标志：

public class DoubleBufferedListBox : ListBox {
    protected override CreateParams CreateParams {
        get {
            CreateParams cp = base.CreateParams;
            cp.ExStyle |= 0x02000000;   // WS_EX_COMPOSITED
            return cp;
        }
    }

    public DoubleBufferedListBox( ) {
        this.SetStyle(ControlStyles.DoubleBuffer, true);         
        this.SetStyle(ControlStyles.OptimizedDoubleBuffer, true);
    }
}