c# - 在数字之后的 NumericUpDown 控件中包含文本

Question

WinForms 是否可以在 NumericUpDown 控件中显示文本？例如，我想在 numericupdown 控件中显示值是微安，所以它应该像“1 uA”。

谢谢。

Answer 1

标准控件中没有内置这样的功能。NumericUpDown但是，通过创建从类继承并重写UpdateEditText方法以相应地格式化数字的自定义控件来添加它是相当容易的。

例如，您可能有以下类定义：

public class NumericUpDownEx : NumericUpDown
{
    public NumericUpDownEx()
    {
    }

    protected override void UpdateEditText()
    {
        // Append the units to the end of the numeric value
        this.Text = this.Value + " uA";
    }
}

或者，对于更完整的实现，请参阅此示例项目：NumericUpDown with unit measure

Answer 2

使用CodeGray 的回答、Fabio 的关于它失败 ValidateEditText 的评论以及NumericUpDown 文档，我想出了一个简单的 NumericUpDownWithUnit 组件。您可以按原样复制/粘贴：

using System;
using System.Globalization;
using System.Text.RegularExpressions;
using System.Windows.Forms;

public class NumericUpDownWithUnit : NumericUpDown
{
    #region| Fields |

    private string unit = null;
    private bool unitFirst = true;

    #endregion

    #region| Properties |

    public string Unit
    {
        get => unit;
        set
        {
            unit = value;

            UpdateEditText();
        }
    }

    public bool UnitFirst
    {
        get => unitFirst;
        set
        {
            unitFirst = value;

            UpdateEditText();
        }
    }

    #endregion

    #region| Methods |

    /// <summary>
    /// Method called when updating the numeric updown text.
    /// </summary>
    protected override void UpdateEditText()
    {
        // If there is a unit we handle it ourselfs, if there is not we leave it to the base class.
        if (Unit != null && Unit != string.Empty)
        {
            if (UnitFirst)
            {
                Text = $"({Unit}) {Value}";
            }
            else
            {
                Text = $"{Value} ({Unit})";
            }
        }
        else
        {
            base.UpdateEditText();
        }
    }

    /// <summary>
    /// Validate method called before actually updating the text.
    /// This is exactly the same as the base class but it will use the new ParseEditText from this class instead.
    /// </summary>
    protected override void ValidateEditText()
    {
        // See if the edit text parses to a valid decimal considering the label unit
        ParseEditText();
        UpdateEditText();
    }

    /// <summary>
    /// Converts the text displayed in the up-down control to a numeric value and evaluates it.
    /// </summary>
    protected new void ParseEditText()
    {
        try
        {
            // The only difference of this methods to the base one is that text is replaced directly
            // with the property Text instead of using the regex.
            // We now that the only characters that may be on the textbox are from the unit we provide.
            // because the NumericUpDown handles invalid input from user for us.
            // This is where the magic happens. This regex will match all characters from the unit
            // (so your unit cannot have numbers). You can change this regex to fill your needs
            var regex = new Regex($@"[^(?!{Unit} )]+");
            var match = regex.Match(Text);

            if (match.Success)
            {
                var text = match.Value;

                // VSWhidbey 173332: Verify that the user is not starting the string with a "-"
                // before attempting to set the Value property since a "-" is a valid character with
                // which to start a string representing a negative number.
                if (!string.IsNullOrEmpty(text) && !(text.Length == 1 && text == "-"))
                {
                    if (Hexadecimal)
                    {
                        Value = Constrain(Convert.ToDecimal(Convert.ToInt32(Text, 16)));
                    }
                    else
                    {
                        Value = Constrain(Decimal.Parse(text, CultureInfo.CurrentCulture));
                    }
                }
            }
        }
        catch
        {
            // Leave value as it is
        }
        finally
        {
            UserEdit = false;
        }
    }

    /// </summary>
    /// Returns the provided value constrained to be within the min and max.
    /// This is exactly the same as the one in base class (which is private so we can't directly use it).
    /// </summary>
    private decimal Constrain(decimal value)
    {
        if (value < Minimum)
        {
            value = Minimum;
        }

        if (value > Maximum)
        {
            value = Maximum;
        }

        return value;
    }

    #endregion
}

Answer 3

这是我用来显示以 0x 为前缀的十六进制 NumericUpDown 的至少 2 位数字的内容。它将文本放在控件中，并通过使用 .Net 提供的字段来避免使用“去抖动”ChangingText

    class HexNumericUpDown2Digits : NumericUpDown
    {
        protected override void UpdateEditText()
        {
            if (Hexadecimal)
            {
                ChangingText = true;
                Text = $"0x{(int)Value:X2}";
            }
            else
            {
                base.UpdateEditText();
            }
        }
    }

Answer 4

我最近偶然发现了这个问题，发现 Cody Gray 的答案很棒。我利用它来发挥自己的优势，但最近对他的回答中的一条评论产生了共鸣，该评论谈到如果后缀仍然存在，文本将如何验证失败。我为此创建了一个可能不太专业的快速修复程序。

基本上，该this.Text字段被读取为数字。

一旦找到数字，它们就会被放入this.Text，但需要进行去抖动或任何您想调用的方法，以确保我们不会创建堆栈溢出。

一旦只有数字的新文本进入，正常的ParseEditText();并被UpdateEditText();调用以完成该过程。

这不是对资源最友好或最有效的解决方案，但当今大多数现代计算机应该完全可以接受。

您还会注意到我创建了一个用于更改后缀的属性，以便在编辑器中更轻松地使用。

public class NumericUpDownUnit : System.Windows.Forms.NumericUpDown
    {

        public string Suffix{ get; set; }

        private bool Debounce = false;

        public NumericUpDownUnit()
        {

        }

        protected override void ValidateEditText()
        {
            if (!Debounce) //I had to use a debouncer because any time you update the 'this.Text' field it calls this method.
            {
                Debounce = true; //Make sure we don't create a stack overflow.

                string tempText = this.Text; //Get the text that was put into the box.
                string numbers = ""; //For holding the numbers we find.

                foreach (char item in tempText) //Implement whatever check wizardry you like here using 'tempText' string.
                {
                    if (Char.IsDigit(item))
                    {
                        numbers += item;
                    }
                    else
                    {
                        break;
                    }
                }

                decimal actualNum = Decimal.Parse(numbers, System.Globalization.NumberStyles.AllowLeadingSign);
                if (actualNum > this.Maximum) //Make sure our number is within min/max
                    this.Value = this.Maximum;
                else if (actualNum < this.Minimum)
                    this.Value = this.Minimum;
                else
                    this.Value = actualNum; 

                ParseEditText(); //Carry on with the normal checks.
                UpdateEditText();

                Debounce = false;
            }

        }

        protected override void UpdateEditText()
        {
            // Append the units to the end of the numeric value
            this.Text = this.Value + Suffix;
        }
    }

如果有问题，请随时改进我的答案或纠正我，我是一名自学成才的程序员，仍在学习。