修改触发器相关的内容

DMS.WPF/Converters/EmptyCollectionToVisibilityConverter.cs

@@ -0,0 +1,29 @@
+using System;
+using System.Collections;
+using System.Globalization;
+using System.Windows;
+using System.Windows.Data;
+
+namespace DMS.WPF.Converters
+{
+    /// <summary>
+    /// 当集合为空时返回Visibility.Visible，否则返回Visibility.Collapsed
+    /// </summary>
+    public class EmptyCollectionToVisibilityConverter : IValueConverter
+    {
+        public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
+        {
+            if (value is ICollection collection)
+            {
+                return collection.Count == 0 ? Visibility.Visible : Visibility.Collapsed;
+            }
+            
+            return Visibility.Visible;
+        }
+
+        public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
+        {
+            throw new NotImplementedException();
+        }
+    }
+}

DMS.WPF/Views/Dialogs/TriggerDialog.xaml

@@ -26,6 +26,7 @@
     <ui:ContentDialog.Resources>
         <converters:EnumToVisibilityConverter x:Key="LocalEnumToVisibilityConverter" />
         <converters:IntToVisibilityConverter x:Key="IntToVisibilityConverter" />
+        <converters:EmptyCollectionToVisibilityConverter x:Key="EmptyCollectionToVisibilityConverter" />
         <ex:EnumBindingSource x:Key="ConditionTypeEnum"
                               EnumType="{x:Type enums:ConditionType}" />
         <ex:EnumBindingSource x:Key="ActionTypeEnum"
@@ -92,7 +93,7 @@
                             <TextBlock Text="暂无选择的变量" 
                                        FontStyle="Italic" 
                                        Foreground="Gray"
-                                       Visibility="{Binding SelectedVariables.Count, Converter={StaticResource IntToVisibilityConverter}, ConverterParameter=0}"/>
+                                       Visibility="{Binding SelectedVariables, Converter={StaticResource EmptyCollectionToVisibilityConverter}}"/>
                         </WrapPanel>
                     </Border>