Merge pull request #31 from gaviny82/fix-combobox-right-alignment

[Settings] Fix flyout position when ComboBox is aligned to the right

Natsurainko.FluentLauncher/Behaviors/SetComboBoxWidthFromItemsBehavior.cs

@@ -0,0 +1,105 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using System.Windows.Threading;
+using Microsoft.UI.Dispatching;
+using Microsoft.UI.Xaml;
+using Microsoft.UI.Xaml.Automation.Peers;
+using Microsoft.UI.Xaml.Automation.Provider;
+using Microsoft.UI.Xaml.Controls;
+using Microsoft.UI.Xaml.Controls.Primitives;
+using Microsoft.Xaml.Interactivity;
+using Windows.Foundation.Collections;
+
+namespace Natsurainko.FluentLauncher.Behaviors
+{
+    class SetComboBoxWidthFromItemsBehavior : Behavior<ComboBox>
+    {
+        public static readonly DependencyProperty SetComboBoxWidthFromItemsProperty =
+        DependencyProperty.RegisterAttached
+        (
+            "SetComboBoxWidthFromItems",
+            typeof(bool),
+            typeof(SetComboBoxWidthFromItemsBehavior),
+            new PropertyMetadata(false, OnSetComboBoxWidthFromItemsPropertyChanged)
+        );
+
+        public bool SetComboBoxWidthFromItems 
+        { 
+            get => (bool)GetValue(SetComboBoxWidthFromItemsProperty); 
+            set => SetValue(SetComboBoxWidthFromItemsProperty, value);
+        }
+
+        protected override void OnAttached()
+        {
+            AssociatedObject.Loaded += OnComboBoxLoaded;
+            AssociatedObject.Items.VectorChanged += Items_VectorChanged;
+        }
+
+        public void Items_VectorChanged(IObservableVector<object> sender, IVectorChangedEventArgs e)
+        {
+            SetComboBoxWidth(AssociatedObject);
+        }
+
+        private static void OnComboBoxLoaded(object sender, RoutedEventArgs e)
+        {
+            SetComboBoxWidth((ComboBox)sender);
+        }
+
+        private static void OnSetComboBoxWidthFromItemsPropertyChanged(
+            DependencyObject dpo, 
+            DependencyPropertyChangedEventArgs e)
+        {
+            SetComboBoxWidthFromItemsBehavior behavior = (SetComboBoxWidthFromItemsBehavior)dpo;
+            ComboBox comboBox = behavior.AssociatedObject;
+
+            bool newValue = (bool)e.NewValue;
+            bool oldValue = (bool)e.OldValue;
+
+            if (comboBox != null && newValue != oldValue)
+            {
+                if (newValue == true)
+                {
+                    comboBox.Loaded += OnComboBoxLoaded;
+                    comboBox.Items.VectorChanged += behavior.Items_VectorChanged;
+
+                }
+                else
+                {
+                    comboBox.Loaded -= OnComboBoxLoaded;
+                    comboBox.Items.VectorChanged -= behavior.Items_VectorChanged;
+                }
+            }
+        }
+
+        /// <summary>
+        /// Set the width of a ComboBox to the longest item in its drop down menu
+        /// </summary>
+        /// <param name="comboBox">Target</param>
+        private static void SetComboBoxWidth(ComboBox comboBox)
+        {
+            // Open ComboBox drop down and prepare ItemContainerGenerator
+            comboBox.IsDropDownOpen = true;
+            comboBox.ItemContainerGenerator.StartAt(new GeneratorPosition(0, 0), GeneratorDirection.Forward, true);
+
+            double maxWidth = 0;
+            ComboBoxItem? item;
+            while ((item = comboBox.ItemContainerGenerator.GenerateNext(out _) as ComboBoxItem) != null)
+            {
+                item.Measure(new Windows.Foundation.Size(double.PositiveInfinity, double.PositiveInfinity));
+                var size = item.DesiredSize;
+                if (size.Width > maxWidth)
+                {
+                    maxWidth = size.Width;
+                }
+            }
+
+            maxWidth += 20; // This constant adds more space to include the drop down button and paddings
+            comboBox.Width = maxWidth > 70 ? maxWidth : 70; // Ensures a MinWidth of 70 when there is no content; Less width will result in issues with appearance
+            comboBox.ItemContainerGenerator.Stop();
+            comboBox.IsDropDownOpen = false;
+        }
+    }
+}

Natsurainko.FluentLauncher/Views/Pages/Settings/Launch.xaml

@@ -8,7 +8,9 @@
     xmlns:local="using:Natsurainko.FluentLauncher.Views.Pages.Settings"
     xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
     xmlns:vm="using:Natsurainko.FluentLauncher.ViewModels.Pages.Settings"
+    xmlns:behaviors ="using:Natsurainko.FluentLauncher.Behaviors"
     Background="Transparent"
+    xmlns:i="using:Microsoft.Xaml.Interactivity"
     mc:Ignorable="d">
     <Page.DataContext>
         <vm:Launch />
@@ -41,19 +43,23 @@
                                 <Grid.ColumnDefinitions>
                                     <ColumnDefinition Width="Auto" />
                                     <ColumnDefinition Width="15" />
-                                    <ColumnDefinition Width="1*" />
+                                    <ColumnDefinition Width="1*" x:Name="container1"/>
                                 </Grid.ColumnDefinitions>
                                 <TextBlock
                                     x:Uid="Settings_Launch_Item_1"
+                                    HorizontalAlignment="Left"
                                     VerticalAlignment="Center"
                                     Text="Current .minecraft folder:" />
                                 <ComboBox
                                     Grid.Column="2"
                                     HorizontalAlignment="Right"
                                     VerticalAlignment="Center"
-                                    FlowDirection="RightToLeft"
                                     ItemsSource="{Binding GameFolders}"
+                                    MaxWidth="{Binding ElementName=container1, Path=ActualWidth, Mode=OneTime}"
                                     SelectedItem="{Binding CurrentGameFolder, Mode=TwoWay}">
+                                    <i:Interaction.Behaviors>
+                                        <behaviors:SetComboBoxWidthFromItemsBehavior SetComboBoxWidthFromItems="True"/>
+                                    </i:Interaction.Behaviors>
                                     <ComboBox.ItemTemplate>
                                         <DataTemplate x:DataType="x:String">
                                             <TextBlock Text="{Binding}" TextTrimming="CharacterEllipsis" />
@@ -151,7 +157,6 @@
                                     Grid.Column="2"
                                     HorizontalAlignment="Right"
                                     VerticalAlignment="Center"
-                                    FlowDirection="RightToLeft"
                                     ItemsSource="{Binding JavaRuntimes}"
                                     SelectedItem="{Binding CurrentJavaRuntime, Mode=TwoWay}">
                                     <ComboBox.ItemTemplate>