禁用组合框中的特定项目 [英] Disabling particular Items in a Combobox

问题描述

我有一个 WinForms 应用程序，我想知道是否有一种更优雅的方法来禁用 Combobox 项而不更改所有禁用值的 SelectedIndex 属性 -1.

I have a WinForms App and I was wondering if there was a more elegant way of disabling Combobox item without changing the SelectedIndex property -1 for all disabled values.

我一直在谷歌搜索，很多解决方案都涉及 ASP.Net DropDownLists 但这LINK 看起来很有希望.我想我可能需要构建自己的 ComboBox 控件，但在我重新发明轮子之前，我想我会在这里问一下是否可行.

I have been googling and a lot of the solutions involve ASP.Net DropDownLists but this LINK looks promising. I think I may have to build my own ComboBox control but before I re-invent the wheel I figure I would ask here if it was possible.

这是最终解决方案，感谢 Arif Eqbal:

Here is the final solution, thanks to Arif Eqbal:

//Add a Combobox to a form and name it comboBox1
//
    using System;
    using System.Drawing;
    using System.Windows.Forms;

    namespace WindowsFormsApplication6
    {
        public partial class Form1 : Form
        {
            public Form1()
            {
                InitializeComponent();
                this.comboBox1.DrawMode = DrawMode.OwnerDrawFixed;
                this.comboBox1.DrawItem += new System.Windows.Forms.DrawItemEventHandler(this.comboBox1_DrawItem);
                this.comboBox1.SelectedIndexChanged += new System.EventHandler(this.comboBox1_SelectedIndexChanged);
            }

            private void Form1_Load(object sender, EventArgs e)
            {
                this.comboBox1.Items.Add("Test1");
                this.comboBox1.Items.Add("Test2");
                this.comboBox1.Items.Add("Test3");
                this.comboBox1.Items.Add("Test4");
                this.comboBox1.Items.Add("Test5");
                this.comboBox1.Items.Add("Test6");
                this.comboBox1.Items.Add("Test7");
            }

            Font myFont = new Font("Aerial", 10, FontStyle.Underline|FontStyle.Regular);
            Font myFont2 = new Font("Aerial", 10, FontStyle.Italic|FontStyle.Strikeout);

            private void comboBox1_DrawItem(object sender, DrawItemEventArgs e)
            {
                if (e.Index == 1 || e.Index == 4 || e.Index == 5)//We are disabling item based on Index, you can have your logic here
                {
                    e.Graphics.DrawString(comboBox1.Items[e.Index].ToString(), myFont2, Brushes.LightSlateGray, e.Bounds);
                }
                else
                {
                    e.DrawBackground();
                    e.Graphics.DrawString(comboBox1.Items[e.Index].ToString(), myFont, Brushes.Black, e.Bounds);
                    e.DrawFocusRectangle();
                }
            }

            void comboBox1_SelectedIndexChanged(object sender, EventArgs e)
            {
                if (comboBox1.SelectedIndex == 1 || comboBox1.SelectedIndex == 4 || comboBox1.SelectedIndex == 5)
                    comboBox1.SelectedIndex = -1;
            }
        }
    }

推荐答案

试试这个...它是否符合你的目的:

Try this... Does it serve your purpose:

我假设您有一个名为 ComboBox1 的组合框，并且您想禁用第二个项目，即索引为 1 的项目.

I assume you have a combobox called ComboBox1 and you want to disable the second item i.e. an item with index 1.

将组合框的DrawMode属性设置为OwnerDrawFixed，然后处理这两个事件，如下图:

Set the DrawMode property of the combobox to OwnerDrawFixed then handle these two events as shown below:

Font myFont = new Font("Aerial", 10, FontStyle.Regular);

private void comboBox1_DrawItem(object sender, DrawItemEventArgs e)
{        
    if (e.Index == 1) //We are disabling item based on Index, you can have your logic here
    {
        e.Graphics.DrawString(comboBox1.Items[e.Index].ToString(), myFont, Brushes.LightGray, e.Bounds);
    }
    else
    {
        e.DrawBackground();
        e.Graphics.DrawString(comboBox1.Items[e.Index].ToString(), myFont, Brushes.Black, e.Bounds);
        e.DrawFocusRectangle();
    }
} 

void comboBox1_SelectedIndexChanged(object sender, EventArgs e)
{
    if (comboBox1.SelectedIndex == 1)
        comboBox1.SelectedIndex = -1;
}

这篇关于禁用组合框中的特定项目的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！