在 WinForms 中是否可以在 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。
【问题讨论】：
标签： c# .net winforms string numericupdown
标准控件中没有内置这样的功能。但是，通过创建一个继承自 NumericUpDown 类并覆盖 UpdateEditText method 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
【讨论】：
ValidateEditText()的默认实现如果文本中有后缀就会失败。您还必须覆盖 ValidateEditText() 以将文本转换为数值
使用CodeGray's 回答，Fabio's 评论它失败 ValidateEditText 和 NumericUpDown documentation 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
}
【讨论】：
这是我用来显示至少 2 位以 0x 为前缀的十六进制 NumericUpDown 的数字。
它将文本放在控件中，并通过使用提供的 .Net 避免使用“去抖动”
字段ChangingText
class HexNumericUpDown2Digits : NumericUpDown
{
protected override void UpdateEditText()
{
if (Hexadecimal)
{
ChangingText = true;
Text = $"0x{(int)Value:X2}";
}
else
{
base.UpdateEditText();
}
}
}
【讨论】：
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，但最近在他的回答中与一位 cmets 产生了共鸣，他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，this.Text 字段用于读取数字。
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，以确保我们不会造成堆栈溢出。
输入只有数字的新文本后，将调用普通的ParseEditText(); 和UpdateEditText(); 来完成该过程。
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都应该完全可以做到这一点。
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。
【讨论】：