我将如何在文本框样式模板WPF winform中设置minlength属性？ [英] How I will set minlength property in textbox style template WPF winform?

问题描述

大家好，

我的问题是我要在wpf文本框中验证平底锅编号min 10 char和max 10，

如果不是则停止按任意键。 ..



我尝试了什么：



如何绑定文本框绑定事件到datagrid ..

Hi All,
My Problem is i want to validate pan number in wpf textbox min 10 char and max 10,
If Not then restict to press any key...

What I have tried:

how to bind textbox binding event to datagrid..

推荐答案

最简单的方法是处理文本框的 TextChanged 事件，评估每次按键时输入的文字。您需要过滤掉任何非数字字符，并检查 int.Parse 'd值以确保它在范围内。



更多的解决方法涉及创建一个派生自TextBox的新类，它允许程序员将输入限制为仅数值，以及指定有效范围。如果你想走这条路，你可能会找到一些不太精心设计的谷歌搜索。



这是我一直在工作的上。我不能保证完整性或适用性，但它可能提供一个合理的起点。

The simplest way is to handle the TextChanged event for the textbox, to evaluate the text entered at every key press. You'll need to filter out any character that is not numeric, as well as check the int.Parse'd value to make sure it falls within range.

The more volved ways involves creating a new class derived from TextBox that allows the programmer to restrict input to just numeric values, as well as specify valid ranges. If you want to go this route, you might be able to find something with a not-too-carefully crafted google search.

Here's one that I've been working on. I cannot guarantee completeness or suitability, but it might provide a reasonable starting point.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;
using BODCommon;
using ObjectExtensions;


namespace WPFCommon.Controls
{
    /// <summary>
    ///
    /// </summary>
    public class TextBoxNumeric : TextBox
    {
        #region Enumerators

        /// <summary>
        /// The types of numeric values that can be entered with this control
        /// </summary>
        public enum NumericTypes
        {
            /// <summary>
            /// Any integer value  (see comments for GetNumericValue nmethods)
            /// </summary>
            Integer,
            /// <summary>
            /// Any decimal value
            /// </summary>
            Decimal,
            /// <summary>
            /// Any floating point value (see comments for GetNumericValue nmethods)
            /// </summary>
            Double
        }

        #endregion Enumerators

        #region Fields

        private bool eventHooked = false;
        private string thisText = string.Empty;

        #endregion Fields

        #region Attached properties

        /// <summary>
        /// Gets or sets the type of the numeric value to be entered.
        /// </summary>
        public NumericTypes NumericType
        {
            get { return (NumericTypes)this.GetValue(NumericTypeProperty); }
            set { this.SetValue(NumericTypeProperty, value); }
        }

        /// <summary>
        /// Gets or sets the precision value.
        /// </summary>
        public int PrecisionValue
        {
            get { return (int)this.GetValue(PrecisionValueProperty); }
            set { this.SetValue(PrecisionValueProperty, value); }
        }

        /// <summary>
        /// The numeric type attached property
        /// </summary>
        public static readonly DependencyProperty NumericTypeProperty    = DependencyProperty.Register("NumericType",    typeof(NumericTypes), typeof(TextBoxNumeric), new PropertyMetadata(NumericTypes.Double));

        /// <summary>
        /// The precision attached property
        /// </summary>
        public static readonly DependencyProperty PrecisionValueProperty = DependencyProperty.Register("PrecisionValue", typeof(int), typeof(TextBoxNumeric), new PropertyMetadata(2));

        #endregion Attached properties

        #region Constructor/destructor

        /// <summary>
        /// Initializes the <see cref="TextBoxNumeric"/> class.
        /// </summary>
        static TextBoxNumeric()
        {
        }

        /// <summary>
        /// Finalizes an instance of the <see cref="TextBoxNumeric"/> class.
        /// </summary>
        ~TextBoxNumeric()
        {
            if (this.eventHooked)
            {
                // unhook  the preview event
                this.PreviewTextInput += TextBoxNumeric_PreviewTextInput;
            }
        }

        #endregion Constructor/destructor

        /// <summary>
        /// Is called when a control template is applied.
        /// </summary>
        public override void OnApplyTemplate()
        {
            base.OnApplyTemplate();
            if (!this.eventHooked)
            {
                this.eventHooked = true;
                this.PreviewTextInput += TextBoxNumeric_PreviewTextInput;
            }
        }

        /// <summary>
        /// Handles the PreviewTextInput event of the TextBoxNumeric control.
        /// </summary>
        /// <param name="sender">The source of the event.</param>
        /// <param name="e">The <see cref="TextCompositionEventArgs"/> instance containing the event data.</param>
        private void TextBoxNumeric_PreviewTextInput(object sender, TextCompositionEventArgs e)
        {
            switch (this.NumericType)
            {
                case NumericTypes.Integer : this.PreviewAsInteger(ref e); break;
                case NumericTypes.Double  : this.PreviewAsDouble(ref e); break;
                case NumericTypes.Decimal : this.PreviewAsDecimal(ref e); break;
            }
        }

        /// <summary>
        /// Previews as integer.
        /// </summary>
        /// <param name="e">The <see cref="TextCompositionEventArgs"/> instance containing the event data.</param>
        private void PreviewAsInteger(ref TextCompositionEventArgs e)
        {
            string text     = e.Text;
            TextBox textbox = (TextBox)(e.Source);
            if (!text.IsNumeric())
            {
                e.Handled = true;
            }
            if (!e.Handled)
            {
                //this.GetTextBoxText(textbox, ref text);
            }
        }

        /// <summary>
        /// Previews as double.
        /// </summary>
        /// <param name="e">The <see cref="TextCompositionEventArgs"/> instance containing the event data.</param>
        private void PreviewAsDouble(ref TextCompositionEventArgs e)
        {
            string  text       = e.Text;
            TextBox textbox    = (TextBox)(e.Source);
            bool    hasDecimal = textbox.Text.IndexOf(".") >= 0;
            if (text == ".")
            {
                if (hasDecimal)
                {
                    e.Handled = true;
                }
                else
                {
                    hasDecimal = true;
                }
            }
            else if (text != "." && !text.IsNumeric())
            {
                e.Handled = true;
            }
            if (!e.Handled)
            {
                this.GetTextBoxText(textbox, ref text);
                int decLength = text.Length - ((hasDecimal) ? text.IndexOf(".") + 1 : 0);
                if (hasDecimal && decLength > this.PrecisionValue)
                {
                    e.Handled = true;
                }
            }
        }

        /// <summary>
        /// Previews as decimal.
        /// </summary>
        /// <param name="e">The <see cref="TextCompositionEventArgs"/> instance containing the event data.</param>
        private void PreviewAsDecimal(ref TextCompositionEventArgs e)
        {
            string  text       = e.Text;
            TextBox textbox    = (TextBox)(e.Source);
            bool    hasDecimal = textbox.Text.IndexOf(".") >= 0;
            if (text == "." && hasDecimal)
            {
                e.Handled = true;
            }
            else if (text != "." && !text.IsNumeric())
            {
                e.Handled = true;
            }
            if (!e.Handled)
            {
                this.GetTextBoxText(textbox, ref text);
                int decLength = text.Length - ((hasDecimal) ? text.IndexOf(".") + 1 : 0);
                if (hasDecimal && decLength > this.PrecisionValue)
                {
                    e.Handled = true;
                }
            }
        }

        /// <summary>
        /// Gets the text box text for the preview methods.
        /// </summary>
        /// <param name="textbox">The textbox.</param>
        /// <param name="text">The text.</param>
        private void GetTextBoxText(TextBox textbox, ref string text)
        {
            int pos = textbox.SelectionStart;
            if (pos == 0)
            {
                text = string.Format("{0}{1}", text, textbox.Text);
            }
            else if (pos == textbox.Text.Length)
            {
                text = string.Format("{0}{1}", textbox.Text, text);
            }
            else
            {
                List<char> chars = new List<char>();
                chars.AddRange(textbox.Text.ToArray());
                chars.InsertRange(pos, text.ToArray());
                text = string.Empty;
                foreach(char c in chars)
                {
                    text += c;
                }
            }
        }

        /// <summary>
        /// <para>Gets the numeric value respresented by the text. If you need to assign the return value to something other</para>
        /// <para>than an int, double or decimal, you'll have to cast the return value to the desired type. Optionally, you </para>
        /// <para>can add appropriate code to this class to add support for the desired numeric type(s).</para>
        /// <para> </para>
        /// <para>Usage is:</para>
        /// <para>    double value = textbox.GetNumericValue&lt;double&gt;();</para>
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <param name="ignoreException">if set to <c>true</c> this method returns 0 instead of throwing an exception if non-numeric text is encountered.</param>
        /// <returns>
        /// The Text property value as the specified type
        /// </returns>
        public T GetNumericValue<T>(bool ignoreException=true)
        {
            //return (T)Convert.ChangeType(this.Text, typeof(T));
            return this.GetNumericValue((T)Convert.ChangeType(0, typeof(T)), ignoreException);
        }

        /// <summary>
        /// <para>Gets the numeric value represented by the text.If you need to assign the return value to something other</para>
        /// <para>than an int, double or decimal, you'll have to cast the return value to the desired type. Optionally, you </para>
        /// <para>can add appropriate code to this class to add support for the desired numeric type(s).</para>
        /// <para> </para>
        /// <para>Usage is:</para>
        /// <para>    double value = textbox.GetNumericValue&lt;double&gt;();</para>
        /// <para> </para>
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <param name="emptyValue">The value to return if the textbox is empty.</param>
        /// <param name="ignoreException">if set to <c>true</c> this method returns the emptyValue instead of throwing an exception if non-numeric text is encountered.</param>
        /// <returns>
        /// The Text property value as the specified type
        /// </returns>
        /// <exception cref="System.Exception">TextBoxNumeric contains a non-numeric value.</exception>
        public T GetNumericValue<T>(T emptyValue, bool ignoreException=true)
        {
            T result = emptyValue;
            string text = this.Text;
            if (!string.IsNullOrEmpty(text))
            {
                try
                {
                    result = (T)Convert.ChangeType(text, typeof(T));
                }
                catch (Exception ex)
                {
                    if (ignoreException)
                    {
                        result = emptyValue;
                    }
                    else
                    {
                        throw new Exception("TextBoxNumeric contains a non-numeric value.", ex);
                    }
                }
            }
            return result;
        }
    }
}

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