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