功能更新

Melskin/Converters/NullOrEmptyConverter.cs

@@ -0,0 +1,41 @@
+using System.Globalization;
+using System.Windows.Data;
+
+namespace Melskin.Converters;
+
+/// <summary>
+/// 支持判断是否为 null 或空字符串，以及是否为非 null 且非空字符串的转换器
+/// </summary>
+public class NullOrEmptyConverter : IValueConverter
+{
+    private readonly bool isNotNullOrEmpty;
+
+    /// <summary>
+    /// 判断对象是否为 null 或空字符串的单例实例
+    /// </summary>
+    public static readonly NullOrEmptyConverter Instance = new(false);
+
+    /// <summary>
+    /// 判断对象是否为非 null 且非空字符串的单例实例
+    /// </summary>
+    public static readonly NullOrEmptyConverter NotInstance = new(true);
+
+    private NullOrEmptyConverter(bool isNotNullOrEmpty = false)
+    {
+        this.isNotNullOrEmpty = isNotNullOrEmpty;
+    }
+
+    /// <inheritdoc/>
+    public object Convert(object? value, Type targetType, object? parameter, CultureInfo culture)
+    {
+        // 如果值为 null 或空字符串，则返回 true；否则返回 false
+        var result = value == null || string.IsNullOrEmpty(value.ToString());
+        return isNotNullOrEmpty ? !result : result;
+    }
+
+    /// <inheritdoc/>
+    public object ConvertBack(object? value, Type targetType, object? parameter, CultureInfo culture)
+    {
+        return DependencyProperty.UnsetValue;
+    }
+}