From ed31e13ff3cf076f459ba1349945a06957f4b104 Mon Sep 17 00:00:00 2001
From: Marcel Wagner <marcel.alex.wagner@outlook.com>
Date: Sun, 31 Oct 2021 23:11:24 +0100
Subject: [PATCH] [TabView] Fix bug where removing tabs from tabcollection
 would not resize tabs (#6160)

---
 dev/TabView/InteractionTests/TabViewTests.cs  | 89 +++++++++++++++++++
 dev/TabView/TabView.cpp                       | 13 ++-
 dev/TabView/TabView.h                         |  3 +
 .../TestUI/TabViewTabClosingBehaviorPage.xaml |  6 +-
 .../TabViewTabClosingBehaviorPage.xaml.cs     | 21 ++++-
 .../MUXTestInfra/Infra/Application.cs         |  4 +-
 6 files changed, 126 insertions(+), 10 deletions(-)

diff --git a/dev/TabView/InteractionTests/TabViewTests.cs b/dev/TabView/InteractionTests/TabViewTests.cs
index 8408c0da79..f7361aee35 100755
--- a/dev/TabView/InteractionTests/TabViewTests.cs
+++ b/dev/TabView/InteractionTests/TabViewTests.cs
@@ -795,6 +795,95 @@ double GetActualTabViewWidth()
             }
         }
 
+        [TestMethod]
+        public void VerifySizingBehaviorModifyingCollectionRemovingLastItem()
+        {
+            int pixelTolerance = 5;
+
+            using (var setup = new TestSetupHelper(new[] { "TabView Tests", "TabViewTabClosingBehaviorButton" }))
+            {
+
+                Log.Comment("Verifying sizing behavior when removing the last tab from tab collection");
+                CloseTabAndVerifyWidth("Tab 5", 500, 100);
+
+                CloseTabAndVerifyWidth("Tab 4", 500, 100);
+
+                CloseTabAndVerifyWidth("Tab 3", 500, 140);
+
+                CloseTabAndVerifyWidth("Tab 2", 500, 225);
+            }
+
+            void CloseTabAndVerifyWidth(string tabName, int expectedWidth, int expectedItemWidth)
+            {
+                Log.Comment("Closing tab:" + tabName);
+                new Button(FindElement.ByName("RemoveLastItemButton")).Click();
+                Wait.ForIdle();
+                new Button(FindElement.ByName("GetActualWidthButton")).Click(); 
+                Log.Comment("Verifying TabView width");
+                Verify.IsTrue(Math.Abs(GetActualTabViewWidth() - expectedWidth) < pixelTolerance);
+                var firstTabItemWidth = GetFirstTabItemWidth();
+                Verify.IsTrue(Math.Abs(firstTabItemWidth - expectedItemWidth) < pixelTolerance);
+            }
+
+            double GetActualTabViewWidth()
+            {
+                var tabviewWidth = new TextBlock(FindElement.ByName("TabViewWidth"));
+
+                return double.Parse(tabviewWidth.GetText());
+            }
+
+            double GetFirstTabItemWidth()
+            {
+                var tabviewWidth = new TextBlock(FindElement.ByName("TabViewHeaderWidth"));
+
+                return double.Parse(tabviewWidth.GetText().Split(".")[0]);
+            }
+        }
+
+        [TestMethod]
+        public void VerifySizingBehaviorModifyingCollectionRemovingSecondItem()
+        {
+            int pixelTolerance = 5;
+
+            using (var setup = new TestSetupHelper(new[] { "TabView Tests", "TabViewTabClosingBehaviorButton" }))
+            {
+
+                Log.Comment("Verifying sizing behavior when removing the second tab from tab collection");
+                CloseTabAndVerifyWidth("Tab 5", 500, 100);
+
+                CloseTabAndVerifyWidth("Tab 4", 500, 100);
+
+                CloseTabAndVerifyWidth("Tab 3", 500, 140);
+
+                CloseTabAndVerifyWidth("Tab 2", 500, 225);
+            }
+
+            void CloseTabAndVerifyWidth(string tabName, int expectedWidth, int expectedItemWidth)
+            {
+                Log.Comment("Closing tab:" + tabName);
+                new Button(FindElement.ByName("RemoveMiddleItemButton")).Click();
+                Wait.ForIdle();
+                new Button(FindElement.ByName("GetActualWidthButton")).Click();
+                Log.Comment("Verifying TabView width");
+                Verify.IsTrue(Math.Abs(GetActualTabViewWidth() - expectedWidth) < pixelTolerance);
+                Verify.IsTrue(Math.Abs(GetFirstTabItemWidth() - expectedItemWidth) < pixelTolerance);
+            }
+
+            double GetActualTabViewWidth()
+            {
+                var tabviewWidth = new TextBlock(FindElement.ByName("TabViewWidth"));
+
+                return double.Parse(tabviewWidth.GetText());
+            }
+
+            double GetFirstTabItemWidth()
+            {
+                var tabviewWidth = new TextBlock(FindElement.ByName("TabViewHeaderWidth"));
+
+                return double.Parse(tabviewWidth.GetText().Split(".")[0]);
+            }
+        }
+
         [TestMethod]
         public void VerifySizingBehaviorOnTabCloseComingFromCtrlF4()
         {
diff --git a/dev/TabView/TabView.cpp b/dev/TabView/TabView.cpp
index 0c0237b635..f88ea86d25 100755
--- a/dev/TabView/TabView.cpp
+++ b/dev/TabView/TabView.cpp
@@ -86,6 +86,7 @@ void TabView::OnApplyTemplate()
     {
         m_tabContainerGrid.set(containerGrid);
         m_tabStripPointerExitedRevoker = containerGrid.PointerExited(winrt::auto_revoke, { this,&TabView::OnTabStripPointerExited });
+        m_tabStripPointerEnteredRevoker = containerGrid.PointerEntered(winrt::auto_revoke, { this,&TabView::OnTabStripPointerEntered });
     }
 
     if (!SharedHelpers::Is21H1OrHigher())
@@ -355,6 +356,7 @@ void TabView::UnhookEventsAndClearFields()
     m_addButtonClickRevoker.revoke();
     m_itemsPresenterSizeChangedRevoker.revoke();
     m_tabStripPointerExitedRevoker.revoke();
+    m_tabStripPointerEnteredRevoker.revoke();
     m_scrollViewerLoadedRevoker.revoke();
     m_scrollViewerViewChangedRevoker.revoke();
     m_scrollDecreaseClickRevoker.revoke();
@@ -508,6 +510,7 @@ void TabView::OnListViewLoaded(const winrt::IInspectable&, const winrt::RoutedEv
 
 void TabView::OnTabStripPointerExited(const winrt::IInspectable& sender, const winrt::PointerRoutedEventArgs& args)
 {
+    m_pointerInTabstrip = false;
     if (m_updateTabWidthOnPointerLeave)
     {
         auto scopeGuard = gsl::finally([this]()
@@ -518,6 +521,11 @@ void TabView::OnTabStripPointerExited(const winrt::IInspectable& sender, const w
     }
 }
 
+void TabView::OnTabStripPointerEntered(const winrt::IInspectable& sender, const winrt::PointerRoutedEventArgs& args)
+{
+    m_pointerInTabstrip = true;
+}
+
 void TabView::OnScrollViewerLoaded(const winrt::IInspectable&, const winrt::RoutedEventArgs& args)
 {
     if (auto&& scrollViewer = m_scrollViewer.get())
@@ -678,12 +686,9 @@ void TabView::OnItemsChanged(winrt::IInspectable const& item)
                 }
 
             }
-            // Last item removed, update sizes
-            // The index of the last element is "Size() - 1", but in TabItems, it is already removed.
             if (TabWidthMode() == winrt::TabViewWidthMode::Equal)
             {
-                m_updateTabWidthOnPointerLeave = true;
-                if (args.Index() == TabItems().Size())
+                if (!m_pointerInTabstrip || args.Index() == TabItems().Size())
                 {
                     UpdateTabWidths(true, false);
                 }
diff --git a/dev/TabView/TabView.h b/dev/TabView/TabView.h
index 7ed2aee08e..3cec00eb31 100755
--- a/dev/TabView/TabView.h
+++ b/dev/TabView/TabView.h
@@ -134,6 +134,7 @@ class TabView :
 
     void OnListViewLoaded(const winrt::IInspectable& sender, const winrt::RoutedEventArgs& args);
     void OnTabStripPointerExited(const winrt::IInspectable& sender, const winrt::PointerRoutedEventArgs& args);
+    void OnTabStripPointerEntered(const winrt::IInspectable& sender, const winrt::PointerRoutedEventArgs& args);
     void OnListViewSelectionChanged(const winrt::IInspectable& sender, const winrt::SelectionChangedEventArgs& args);
 
     void OnListViewDragItemsStarting(const winrt::IInspectable& sender, const winrt::DragItemsStartingEventArgs& args);
@@ -166,6 +167,7 @@ class TabView :
     winrt::TabViewItem FindTabViewItemFromDragItem(const winrt::IInspectable& item);
 
     bool m_updateTabWidthOnPointerLeave{ false };
+    bool m_pointerInTabstrip{ false };
 
     tracker_ref<winrt::ColumnDefinition> m_leftContentColumn{ this };
     tracker_ref<winrt::ColumnDefinition> m_tabColumn{ this };
@@ -186,6 +188,7 @@ class TabView :
 
     winrt::ListView::Loaded_revoker m_listViewLoadedRevoker{};
     winrt::ListView::PointerExited_revoker m_tabStripPointerExitedRevoker{};
+    winrt::ListView::PointerEntered_revoker m_tabStripPointerEnteredRevoker{};
     winrt::Selector::SelectionChanged_revoker m_listViewSelectionChangedRevoker{};
     winrt::UIElement::GettingFocus_revoker m_listViewGettingFocusRevoker{};
 
diff --git a/dev/TabView/TestUI/TabViewTabClosingBehaviorPage.xaml b/dev/TabView/TestUI/TabViewTabClosingBehaviorPage.xaml
index 07a803a666..23a15af2a7 100644
--- a/dev/TabView/TestUI/TabViewTabClosingBehaviorPage.xaml
+++ b/dev/TabView/TestUI/TabViewTabClosingBehaviorPage.xaml
@@ -20,10 +20,10 @@
                     TabCloseRequested="TabViewTabCloseRequested"
                     AddTabButtonClick="AddButtonClick">
 
-                    <muxc:TabViewItem Header="Tab 0" AutomationProperties.Name="Tab 0"/>
+                    <muxc:TabViewItem Header="Tab 0" x:Name="Tab0" AutomationProperties.Name="Tab 0"/>
                     <muxc:TabViewItem Header="Tab 1" AutomationProperties.Name="Tab 1"/>
                     <muxc:TabViewItem Header="Tab 2" AutomationProperties.Name="Tab 2"/>
-                    <muxc:TabViewItem Header="Tab 3" x:Name="Tab3" AutomationProperties.Name="Tab 3"/>
+                    <muxc:TabViewItem Header="Tab 3" AutomationProperties.Name="Tab 3"/>
                     <muxc:TabViewItem Header="Tab 4" AutomationProperties.Name="Tab 4"/>
                     <muxc:TabViewItem Header="Tab 5" AutomationProperties.Name="Tab 5"/>
                 </muxc:TabView>
@@ -43,6 +43,8 @@
                 <Button AutomationProperties.Name="IncreaseScrollButton"
                         Click="IncreaseScrollButton_Click"
                         Content="Increase scroll" />
+                <Button AutomationProperties.Name="RemoveMiddleItemButton" Click="RemoveMiddleItem_Click" Content="Remove Middle item"/>
+                <Button AutomationProperties.Name="RemoveLastItemButton" Click="RemoveLastItem_Click" Content="Remove last item"/>
             </StackPanel>
         </StackPanel>
     </Grid>
diff --git a/dev/TabView/TestUI/TabViewTabClosingBehaviorPage.xaml.cs b/dev/TabView/TestUI/TabViewTabClosingBehaviorPage.xaml.cs
index 89ddb2067e..f55e246aad 100644
--- a/dev/TabView/TestUI/TabViewTabClosingBehaviorPage.xaml.cs
+++ b/dev/TabView/TestUI/TabViewTabClosingBehaviorPage.xaml.cs
@@ -50,7 +50,7 @@ private void TabViewTabCloseRequested(object sender, Microsoft.UI.Xaml.Controls.
             Tabs.TabItems.Remove(e.Tab);
 
             TabViewWidth.Text = Tabs.ActualWidth.ToString();
-            TabViewHeaderWidth.Text = Tab3.Width.ToString();
+            TabViewHeaderWidth.Text = Tab0.Width.ToString();
 
             var scrollButtonStateValue = "";
 
@@ -63,13 +63,21 @@ private void TabViewTabCloseRequested(object sender, Microsoft.UI.Xaml.Controls.
             ScrollButtonStatus.Text = scrollButtonStateValue;
         }
 
+        public void GetFirstItemWidthButton_Click(object sender, RoutedEventArgs e)
+        {
+            // This is the smallest width that fits our content without any scrolling.
+            TabViewWidth.Text = Tabs.ActualWidth.ToString();
+
+            // Header width
+            TabViewHeaderWidth.Text = Tab0.Width.ToString();
+        }
         public void GetActualWidthsButton_Click(object sender, RoutedEventArgs e)
         {
             // This is the smallest width that fits our content without any scrolling.
             TabViewWidth.Text = Tabs.ActualWidth.ToString();
 
             // Header width
-            TabViewHeaderWidth.Text = Tab3.Width.ToString();
+            TabViewHeaderWidth.Text = Tab0.Width.ToString();
         }
 
         public void IncreaseScrollButton_Click(object sender, RoutedEventArgs e)
@@ -78,5 +86,14 @@ public void IncreaseScrollButton_Click(object sender, RoutedEventArgs e)
             sv.ChangeView(10000, null, null, disableAnimation: true);
         }
 
+        private void RemoveMiddleItem_Click(object sender, RoutedEventArgs e)
+        {
+            Tabs.TabItems.RemoveAt(1);
+        }
+
+        private void RemoveLastItem_Click(object sender, RoutedEventArgs e)
+        {
+            Tabs.TabItems.RemoveAt(Tabs.TabItems.Count - 1);
+        }
     }
 }
diff --git a/test/testinfra/MUXTestInfra/Infra/Application.cs b/test/testinfra/MUXTestInfra/Infra/Application.cs
index c5572fd5a2..aa6c9f664e 100644
--- a/test/testinfra/MUXTestInfra/Infra/Application.cs
+++ b/test/testinfra/MUXTestInfra/Infra/Application.cs
@@ -274,7 +274,7 @@ private UIObject LaunchApp()
                 catch (Exception ex)
                 {
                     Log.Comment("Failed to launch app. Exception: " + ex.ToString());
-                    
+
                     if (retries < MaxLaunchRetries)
                     {
                         Log.Comment("UAPApp.Launch might not have waited long enough, trying again {0}", retries);
@@ -354,7 +354,7 @@ private void EnsureApplicationProcessHasExited(int appWindowsProccessId)
             // 3. Use the Process obj we found when this Application object was initialized.
             // This is just a sanity check. Under normal circumstances, there should only be 
             // one app process. 
-            
+
             var appProcesses = Process.GetProcessesByName(_appProcessName).ToList();
 
             if (appWindowsProccessId != -1)