winforms ComboBox中的单个项目颜色？

Question

我有一个困境,我有一个表格,其中包含许多组合框,其中包含在某些情况下可能无效/过期的信息/选项/项目.

我不能简单地从项目中删除过时的信息,但我确实希望在选项无效时给用户一个直观的线索.

我想在项目中着色(可能是红色)来表明它们是否及何时无效.我不一定需要阻止用户选择无效选项,只是让他们在视觉上意识到他们正在这样做.

可以这样做吗？你能 - 动态地 - 改变组合框的colo(u)r吗？

谢谢,

Answer 1

您可以尝试ComboBox的DrawItem事件.将您的日期保留在列表中,并将其与ID进行比较并刷新您的项目.

private void comboBox1_DrawItem(object sender, DrawItemEventArgs e)
{    
    // Draw the background 
    e.DrawBackground();        

    // Get the item text    
    string text = ((ComboBox)sender).Items[e.Index].ToString();

    // Determine the forecolor based on whether or not the item is selected    
    Brush brush;
    if (YourListOfDates[e.Index] < DateTime.Now)// compare  date with your list.  
    {
        brush = Brushes.Red;
    }
    else
    {
        brush = Brushes.Green;
    }

    // Draw the text    
    e.Graphics.DrawString(text, ((Control)sender).Font, brush, e.Bounds.X, e.Bounds.Y);
}

解雇此事件(感谢@Bolu)

您需要将ComboBox.DrawMode更改为OwnerDrawFixed/OwnerDrawVariable以触发comboBox_DrawItem

Answer 2

///The ComboBoxCustom Control:

using System;
using System.Windows.Forms;
using System.Drawing;
namespace TyroDeveloper
{
    public class ComboBoxCustom:ComboBox
    {
        public ComboBoxCustom() { 
            this.DrawMode = System.Windows.Forms.DrawMode.OwnerDrawFixed; 
        }
        protected override void OnDrawItem(DrawItemEventArgs e)
        {
            base.OnDrawItem(e);
            e.DrawBackground();
            ComboBoxItem item = (ComboBoxItem)this.Items[e.Index];
            Brush brush = new SolidBrush(item.ForeColor);
            if ((e.State & DrawItemState.Selected) == DrawItemState.Selected) 
            { brush = Brushes.Yellow; }
            e.Graphics.DrawString(item.Text, this.Font, brush, e.Bounds.X, e.Bounds.Y);
        }
    }
    public class ComboBoxItem
    {
        public ComboBoxItem() { }

        public ComboBoxItem(string pText, object pValue)
        {
            text = pText; val = pValue;
        }

        public ComboBoxItem(string pText, object pValue, Color pColor)
        {
            text = pText; val = pValue; foreColor = pColor;
        }

        string text = "";
        public string Text { 
            get { return text; } set { text = value; } 
        }

        object val;
        public object Value { 
            get { return val; } set { val = value; } 
        }

        Color foreColor = Color.Black;
        public Color ForeColor { 
            get { return foreColor; } set { foreColor = value; } 
        }

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

//To add the items:

comboBoxCustom1.Items.Add(new ComboBoxItem("México","0",Color.Green));
comboBoxCustom1.Items.Add(new ComboBoxItem("USA", "1", Color.Blue));
comboBoxCustom1.Items.Add(new ComboBoxItem("China", "2", Color.Red));

源网址页面:http: //www.tyrodeveloper.com/2012/04/color-in-combobox-item.html