Remove White background of list (microsoft#2218)

* Remove white background of list

* Removed comments

* Changed to ContainerContentChanging event

* add const variables instead of numbers

* Added comment before the updatelistSize function

src/modules/launcher/PowerLauncher/MainWindow.xaml.cs

@@ -32,6 +32,10 @@ public partial class MainWindow
         private Settings _settings;
         private MainViewModel _viewModel;
 
+        const int ROW_COUNT = 4;
+        const int ROW_HEIGHT = 75;
+        const int MAX_LIST_HEIGHT = 300;
+
         #endregion
 
         public MainWindow(Settings settings, MainViewModel mainVM)
@@ -225,8 +229,10 @@ private void WindowsXamlHostListView_ChildChanged(object sender, EventArgs ev)
             _resultList.DataContext = _viewModel;
             _resultList.Tapped += SuggestionsList_Tapped;
             _resultList.SuggestionsList.SelectionChanged += SuggestionsList_SelectionChanged;
+            _resultList.SuggestionsList.ContainerContentChanging += SuggestionList_UpdateListSize;
         }
 
+
         private bool IsKeyDown(VirtualKey key)
         {
             var keyState = CoreWindow.GetForCurrentThread().GetKeyState(key);
@@ -283,6 +289,17 @@ private void SuggestionsList_Tapped(object sender, TappedRoutedEventArgs e)
             }
         }
 
+        /* Note: This function has been added because a white-background was observed when the list resized,
+         * when the number of elements were lesser than the maximum capacity of the list (ie. 4).
+         * Binding Height/MaxHeight Properties did not solve this issue.
+         */
+        private void SuggestionList_UpdateListSize(object sender, ContainerContentChangingEventArgs e)
+        {
+            int count = _viewModel?.Results?.Results.Count ?? 0;
+            int maxHeight = count < ROW_COUNT ? count * ROW_HEIGHT : MAX_LIST_HEIGHT;
+            _resultList.Height = maxHeight;
+        }
+
         private void SuggestionsList_SelectionChanged(object sender, Windows.UI.Xaml.Controls.SelectionChangedEventArgs e)
         {
             Windows.UI.Xaml.Controls.ListView listview = (Windows.UI.Xaml.Controls.ListView)sender;

src/modules/launcher/PowerLauncher/ResultListBox.xaml

@@ -7,7 +7,6 @@
          xmlns:converter="clr-namespace:Wox.Converters;assembly=Wox"
          mc:Ignorable="d" d:DesignWidth="100" d:DesignHeight="100"
          d:DataContext="{d:DesignInstance vm:ResultsViewModel}"
-         MaxHeight="{Binding MaxHeight}"
          SelectedIndex="{Binding SelectedIndex, Mode=TwoWay}"
          SelectedItem="{Binding SelectedItem, Mode=OneWayToSource}"
          HorizontalContentAlignment="Stretch" ItemsSource="{Binding Results}"