C# winforms 组合框动态自动完成 [英] C# winforms combobox dynamic autocomplete

问题描述

我的问题与此类似:如何动态更改 C# 组合框或文本框中的自动完成条目?但我仍然没有找到解决方案.

My problem is similar to this one: How can I dynamically change auto complete entries in a C# combobox or textbox? But I still don't find solution.

问题简述:

我有一个 ComboBox 和大量要在其中显示的记录.当用户开始输入时，我想加载以输入文本开头的记录并为用户提供自动完成功能.如上述主题所述，我无法在 сomboBox_TextChanged 上加载它们，因为我总是覆盖以前的结果并且从未看到它们.

I have an ComboBox and a large number of records to show in it. When user starts typing I want to load records that starts with input text and offer the user for autocomplete. As described in the topic above I can't load them on сomboBox_TextChanged because I always overwrite the previous results and never see them.

我可以仅使用 ComboBox 来实现吗?(不是 TextBox 或 ListBox)

Can I implement this using only ComboBox? (not TextBox or ListBox)

我使用这个设置:

сomboBox.AutoCompleteMode = AutoCompleteMode.SuggestAppend;
сomboBox.AutoCompleteSource = AutoCompleteSource.CustomSource;

推荐答案

这是我的最终解决方案.它适用于大量数据.我使用 Timer 来确保用户想要找到当前值.看起来很复杂，其实不然.感谢 Max Lambertini 提出这个想法.

Here is my final solution. It works fine with a large amount of data. I use Timer to make sure the user want find current value. It looks like complex but it doesn't. Thanks to Max Lambertini for the idea.

        private bool _canUpdate = true; 

        private bool _needUpdate = false;       

        //If text has been changed then start timer
        //If the user doesn't change text while the timer runs then start search
        private void combobox1_TextChanged(object sender, EventArgs e)
        {
            if (_needUpdate)
            {
                if (_canUpdate)
                {
                    _canUpdate = false;
                    UpdateData();                   
                }
                else
                {
                    RestartTimer();
                }
            }
        }

        private void UpdateData()
        {
            if (combobox1.Text.Length > 1)
            {
                List<string> searchData = Search.GetData(combobox1.Text);
                HandleTextChanged(searchData);
            }
        }       

        //If an item was selected don't start new search
        private void combobox1_SelectedIndexChanged(object sender, EventArgs e)
        {
            _needUpdate = false;
        }

        //Update data only when the user (not program) change something
        private void combobox1_TextUpdate(object sender, EventArgs e)
        {
            _needUpdate = true;
        }

        //While timer is running don't start search
        //timer1.Interval = 1500;
        private void RestartTimer()
        {
            timer1.Stop();
            _canUpdate = false;
            timer1.Start();
        }

        //Update data when timer stops
        private void timer1_Tick(object sender, EventArgs e)
        {
            _canUpdate = true;
            timer1.Stop();
            UpdateData();
        }

        //Update combobox with new data
        private void HandleTextChanged(List<string> dataSource)
        {
            var text = combobox1.Text;

            if (dataSource.Count() > 0)
            {
                combobox1.DataSource = dataSource;  

                var sText = combobox1.Items[0].ToString();
                combobox1.SelectionStart = text.Length;
                combobox1.SelectionLength = sText.Length - text.Length;
                combobox1.DroppedDown = true;


                return;
            }
            else
            {
                combobox1.DroppedDown = false;
                combobox1.SelectionStart = text.Length;
            }
        }

这个解决方案不是很酷.所以如果有人有其他解决方案，请与我分享.

This solution isn't very cool. So if someone has another solution please share it with me.

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