ShrlAlgoToolkit/Melskin/Assists/InputAssist.cs

using System.Windows.Controls.Primitives;

using Melskin.Extensions;

namespace Melskin.Assists;

/// <summary>
/// InputAssist 类提供了一系列附加属性，用于增强 WPF 应用程序中输入控件的功能。这些功能包括设置占位符文本、占位符颜色、前缀和后缀内容等，支持 TextBoxBase、PasswordBox 和 ComboBox 控件。
/// </summary>
public static class InputAssist
{
    #region Attached Properties

    /// <summary>
    /// 用于设置或获取控件的占位符文本。
    /// </summary>
    public static readonly DependencyProperty PlaceholderTextProperty =
        DependencyProperty.RegisterAttached("PlaceholderText", typeof(string), typeof(InputAssist), new PropertyMetadata(string.Empty));

    /// <summary>
    /// 获取输入控件的占位符文本。
    /// </summary>
    [AttachedPropertyBrowsableForType(typeof(TextBoxBase))]
    [AttachedPropertyBrowsableForType(typeof(PasswordBox))]
    [AttachedPropertyBrowsableForType(typeof(ComboBox))]
    public static string GetPlaceholderText(DependencyObject obj)
    {
        return (string)obj.GetValue(PlaceholderTextProperty);
    }

    /// <summary>
    /// 设置输入控件的占位符。
    /// </summary>
    /// <param name="obj">要设置占位符的依赖对象。</param>
    /// <param name="value">占位符的文本值。</param>
    public static void SetPlaceholderText(DependencyObject obj, string value)
    {
        obj.SetValue(PlaceholderTextProperty, value);
    }

    /// <summary>
    /// 用于设置或获取控件的前缀内容。
    /// </summary>
    public static readonly DependencyProperty PrefixProperty =
        DependencyProperty.RegisterAttached("Prefix", typeof(object), typeof(InputAssist), new PropertyMetadata(null));

    /// <summary>
    /// 获取与指定依赖对象关联的前缀。
    /// </summary>
    /// <param name="obj">要获取前缀的依赖对象。</param>
    /// <returns>与指定依赖对象关联的前缀对象。</returns>
    [AttachedPropertyBrowsableForType(typeof(TextBox))]
    [AttachedPropertyBrowsableForType(typeof(PasswordBox))]
    [AttachedPropertyBrowsableForType(typeof(ComboBox))]
    public static object GetPrefix(DependencyObject obj)
    {
        return obj.GetValue(PrefixProperty);
    }

    /// <summary>
    /// 设置输入控件的前缀。
    /// </summary>
    /// <param name="obj">要设置前缀的依赖对象。</param>
    /// <param name="value">要设置为前缀的对象。</param>
    public static void SetPrefix(DependencyObject obj, object value)
    {
        obj.SetValue(PrefixProperty, value);
    }
    // 这是一个只读的依赖属性，用于向XAML报告PasswordBox是否有文本。
    // 只有这个类内部可以通过Key来修改它的值，保证了状态的可靠性。
    private static readonly DependencyPropertyKey HasTextPropertyKey =
        DependencyProperty.RegisterAttachedReadOnly(
            "HasPassword",
            typeof(bool),
            typeof(InputAssist),
            new PropertyMetadata(false));

    /// <summary>
    /// 用于获取或设置是否显示密码框内有内容的指示器。
    /// </summary>
    public static readonly DependencyProperty HasPasswordProperty = HasTextPropertyKey.DependencyProperty;

    /// <summary>
    /// 获取指定控件是否启用了密码模式。
    /// </summary>
    /// <param name="obj">要检查的DependencyObject对象。</param>
    /// <returns>如果控件启用了密码模式，则返回true；否则返回false。</returns>
    [AttachedPropertyBrowsableForType(typeof(PasswordBox))]
    public static bool GetHasPassword(DependencyObject obj)
    {
        return (bool)obj.GetValue(HasPasswordProperty);
    }
 

    // 核心更新逻辑
    private static void UpdateHasPassword(PasswordBox passwordBox)
    {
        // 根据密码长度是否大于0，来设置HasText属性的值
        passwordBox.SetValue(HasTextPropertyKey, passwordBox.Password.Length > 0);
    }
    /// <summary>
    /// 用于设置或获取附着到控件上的后缀内容。
    /// </summary>
    public static readonly DependencyProperty SuffixProperty =
        DependencyProperty.RegisterAttached("Suffix", typeof(object), typeof(InputAssist), new PropertyMetadata(null));

    /// <summary>
    /// 获取附加到指定控件的后缀内容。
    /// </summary>
    /// <param name="obj">要获取后缀内容的DependencyObject对象。</param>
    /// <returns>返回控件的后缀内容，如果未设置则为null。</returns>
    [AttachedPropertyBrowsableForType(typeof(TextBox))]
    [AttachedPropertyBrowsableForType(typeof(PasswordBox))]
    public static object GetSuffix(DependencyObject obj)
    {
        return obj.GetValue(SuffixProperty);
    }

    /// <summary>
    /// 设置输入控件的后缀。
    /// </summary>
    /// <param name="obj">要设置后缀的依赖对象。</param>
    /// <param name="value">要设置为后缀的对象。</param>
    public static void SetSuffix(DependencyObject obj, object value)
    {
        obj.SetValue(SuffixProperty, value);
    }

    #region PasswordBox

    /// <summary>
    /// 用于设置或获取控件的密码文本。
    /// </summary>
    public static readonly DependencyProperty PasswordProperty =
        DependencyProperty.RegisterAttached("Password", typeof(string), typeof(InputAssist),
            new FrameworkPropertyMetadata(string.Empty, FrameworkPropertyMetadataOptions.BindsTwoWayByDefault, OnPasswordChanged));

    private static void OnPasswordChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
    {
        if (d is PasswordBox passwordBox)
        {
            // 解除再绑定，防止重复订阅
            passwordBox.PasswordChanged -= PasswordBox_PasswordChanged;

            var newVal = (string)e.NewValue ?? string.Empty;
            if (passwordBox.Password != newVal)
            {
                passwordBox.Password = newVal;
            }
            UpdateHasPassword(passwordBox);
            // 确保监听用户输入
            passwordBox.PasswordChanged += PasswordBox_PasswordChanged;
        }
    }

    private static void PasswordBox_PasswordChanged(object sender, RoutedEventArgs e)
    {
        if (sender is not PasswordBox box) return;
        var attached = GetPassword(box);
        var actual = box.Password;

        // 当用户输入变化时同步回附加属性
        if (attached != actual)
        {
            // 这里调用 SetPassword 会再次触发 OnPasswordChanged，但因值相同不会再写入造成循环
            SetPassword(box, actual);
        }
        UpdateHasPassword(box);
    }

    /// <summary>
    /// 获取输入控件的密码文本。
    /// </summary>
    [AttachedPropertyBrowsableForType(typeof(PasswordBox))]
    public static string GetPassword(DependencyObject obj)
    {
        return (string)obj.GetValue(PasswordProperty);
    }

    /// <summary>
    /// 设置输入控件的密码文本。
    /// </summary>
    public static void SetPassword(DependencyObject obj, string value)
    {
        obj.SetValue(PasswordProperty, value);
    }

    /// <summary>
    /// 切换可见密码的样板的作用
    /// </summary>
    public static readonly DependencyProperty IsPasswordVisibleProperty =
        DependencyProperty.RegisterAttached("IsPasswordVisible", typeof(bool), typeof(InputAssist), new PropertyMetadata(false));

    /// <summary>
    /// Gets whether the password currently held by PasswordBox is displayed in text.
    /// </summary>
    [AttachedPropertyBrowsableForType(typeof(PasswordBox))]
    public static bool GetIsPasswordVisible(DependencyObject obj)
    {
        return (bool)obj.GetValue(IsPasswordVisibleProperty);
    }

    /// <summary>
    /// 设置是否可以切换密码框的显示模式（显示/隐藏密码）。
    /// </summary>
    /// <param name="obj">依赖对象，通常是PasswordBox。</param>
    /// <param name="value">布尔值，表示是否启用显示/隐藏密码的功能。</param>
    public static void SetIsPasswordVisible(DependencyObject obj, bool value)
    {
        obj.SetValue(IsPasswordVisibleProperty, value);
    }
    

    #endregion

    /// <summary>
    /// 用于设置或获取控件是否可以被清空。
    /// </summary>
    public static readonly DependencyProperty ClearEnabledProperty =
        DependencyProperty.RegisterAttached("ClearEnabled", typeof(bool), typeof(InputAssist), new PropertyMetadata(false, OnClearEnabledChanged));

    /// <summary>
    /// 获取指定控件是否启用了清除功能。
    /// </summary>
    /// <param name="obj">要获取属性的依赖对象。</param>
    /// <returns>如果启用了清除功能，则返回 true；否则返回 false。</returns>
    [AttachedPropertyBrowsableForType(typeof(TextBox))]
    [AttachedPropertyBrowsableForType(typeof(PasswordBox))]
    [AttachedPropertyBrowsableForType(typeof(ComboBox))]
    public static bool GetClearEnabled(DependencyObject obj)
    {
        return (bool)obj.GetValue(ClearEnabledProperty);
    }


    /// <summary>
    /// 设置输入控件是否可以被清空。
    /// </summary>
    public static void SetClearEnabled(DependencyObject obj, bool value)
    {
        obj.SetValue(ClearEnabledProperty, value);
    }

    private static void OnClearEnabledChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
    {
        if (d is not UIElement element) return;
        // 根据新值订阅或取消订阅鼠标左键释放事件
        if ((bool)e.NewValue)
        {
            element.MouseLeftButtonUp += OnClear;
        }
        else
        {
            element.MouseLeftButtonUp -= OnClear;
        }
    }

    /// <summary>
    /// 用于设置或获取控件是否显示清除按钮。
    /// </summary>
    public static readonly DependencyProperty ClearableProperty = DependencyProperty.RegisterAttached(
        "Clearable", typeof(bool), typeof(InputAssist), new PropertyMetadata(default(bool)));

    /// <summary>
    /// 设置输入控件是否可清除。
    /// </summary>
    /// <param name="d">要设置属性的依赖对象。</param>
    /// <param name="value">布尔值，表示输入控件是否可以被用户清除其内容。</param>
    public static void SetClearable(DependencyObject d, bool value)
    {
        d.SetValue(ClearableProperty, value);
    }

    /// <summary>
    /// 获取指定依赖对象的可清除属性值。
    /// </summary>
    /// <param name="d">要获取属性值的依赖对象。</param>
    /// <returns>返回一个布尔值，表示该控件是否可以被清除内容。</returns>
    public static bool GetClearable(DependencyObject d)
    {
        return (bool)d.GetValue(ClearableProperty);
    }
    #endregion

    #region Private Methods
    /// <summary>
    /// 清除事件的处理程序
    /// </summary>
    /// <param name="sender"></param>
    /// <param name="e"></param>
    private static void OnClear(object sender, RoutedEventArgs e)
    {
        if (sender is not DependencyObject d) return;
        //查找父级控件中第一个是 TextBox、PasswordBox 或 ComboBox 的控件
        var parent = d.GetAncestors().FirstOrDefault(a => a is TextBox or PasswordBox or ComboBox);
        if (parent != null && !GetClearable(parent)) return;
        switch (parent)
        {
            case TextBox textBox:
                textBox.Clear();
                textBox.GetBindingExpression(TextBox.TextProperty)?.UpdateSource();
                break;
            case PasswordBox passwordBox:
                passwordBox.Clear();
                passwordBox.GetBindingExpression(PasswordProperty)?.UpdateSource();
                break;
            case ComboBox comboBox:
            {
                if (comboBox.IsEditable)
                {
                    comboBox.Text = string.Empty;
                    comboBox.GetBindingExpression(ComboBox.TextProperty)?.UpdateSource();
                }

                comboBox.SelectedItem = null;
                comboBox.GetBindingExpression(Selector.SelectedItemProperty)?.UpdateSource();
                break;
            }
        }
    }

    #endregion
}