Support SplitState::Automatic

src/cascadia/TerminalApp/ActionArgs.idl

@@ -26,7 +26,8 @@ namespace TerminalApp
     enum SplitState
     {
         Vertical,
-        Horizontal
+        Horizontal,
+        Automatic
     };
 
     [default_interface] runtimeclass NewTerminalArgs {

src/cascadia/TerminalApp/LeafPane.cpp

@@ -150,6 +150,7 @@ GUID LeafPane::GetProfile() const noexcept
 // - True if the pane can be split. False otherwise.
 bool LeafPane::CanSplit(SplitState splitType)
 {
+    splitType = _ConvertAutomaticSplitState(splitType);
     const Size actualSize{ gsl::narrow_cast<float>(_root.ActualWidth()),
                            gsl::narrow_cast<float>(_root.ActualHeight()) };
 
@@ -189,6 +190,7 @@ std::shared_ptr<LeafPane> LeafPane::Split(winrt::TerminalApp::SplitState splitTy
                                           const GUID& profile,
                                           const winrt::Microsoft::Terminal::TerminalControl::TermControl& control)
 {
+    splitType = _ConvertAutomaticSplitState(splitType);
     const auto newNeighbour = std::make_shared<LeafPane>(profile, control);
 
     // Update the border of this pane and set appropriate border for the new leaf pane.
@@ -228,6 +230,31 @@ std::shared_ptr<LeafPane> LeafPane::Split(winrt::TerminalApp::SplitState splitTy
     return newNeighbour;
 }
 
+// Method Description:
+// - Converts an "automatic" split type into either Vertical or Horizontal,
+//   based upon the current dimensions of the Pane.
+// - If any of the other SplitState values are passed in, they're returned
+//   unmodified.
+// Arguments:
+// - splitType: The SplitState to attempt to convert
+// Return Value:
+// - One of Horizontal or Vertical
+SplitState LeafPane::_ConvertAutomaticSplitState(const SplitState& splitType) const
+{
+    // Careful here! If the pane doesn't yet have a size, these dimensions will
+    // be 0, and we'll always return Vertical.
+
+    if (splitType == SplitState::Automatic)
+    {
+        // If the requested split type was "auto", determine which direction to
+        // split based on our current dimensions
+        const Size actualSize{ gsl::narrow_cast<float>(_root.ActualWidth()),
+                               gsl::narrow_cast<float>(_root.ActualHeight()) };
+        return actualSize.Width >= actualSize.Height ? SplitState::Vertical : SplitState::Horizontal;
+    }
+    return splitType;
+}
+
 // Method Description:
 // - Sets the "Active" state on this pane. Only one pane in a tree of panes
 //   should be "active".

src/cascadia/TerminalApp/LeafPane.h

@@ -81,6 +81,7 @@ class LeafPane : public Pane, public std::enable_shared_from_this<LeafPane>
     std::shared_ptr<LeafPane> _FindFirstLeaf() override;
     void _UpdateBorders();
     void _UpdateVisuals();
+    winrt::TerminalApp::SplitState _ConvertAutomaticSplitState(const winrt::TerminalApp::SplitState& splitType) const;
     SnapSizeResult _CalcSnappedDimension(const bool widthOrHeight, const float dimension) const override;
     void _AdvanceSnappedDimension(const bool widthOrHeight, LayoutSizeNode& sizeNode) const override;
     winrt::Windows::Foundation::Size _GetMinSize() const override;

src/cascadia/TerminalApp/TerminalPage.cpp

@@ -450,6 +450,7 @@ namespace winrt::TerminalApp::implementation
 
         // Add the new tab to the list of our tabs.
         auto newTab = _tabs.emplace_back(std::make_shared<Tab>(profileGuid, term));
+        newTab->BindEventHandlers();
 
         // Hookup our event handlers to the new terminal
         _RegisterTerminalEvents(term, newTab);
@@ -474,6 +475,17 @@ namespace winrt::TerminalApp::implementation
             }
         });
 
+        newTab->RootPaneChanged([weakTabPtr, weakThis{ get_weak() }]() {
+            auto page{ weakThis.get() };
+            auto tab{ weakTabPtr.lock() };
+
+            if (page && tab)
+            {
+                page->_tabContent.Children().Clear();
+                page->_tabContent.Children().Append(tab->GetRootElement());
+            }
+        });
+
         auto tabViewItem = newTab->GetTabViewItem();
         _tabView.TabItems().Append(tabViewItem);
 
@@ -798,9 +810,6 @@ namespace winrt::TerminalApp::implementation
         // Add an event handler when the terminal wants to paste data from the Clipboard.
         term.PasteFromClipboard({ this, &TerminalPage::_PasteFromClipboardHandler });
 
-        // Bind Tab events to the TermControl and the Tab's Pane
-        hostingTab->BindEventHandlers(term);
-
         // Don't capture a strong ref to the tab. If the tab is removed as this
         // is called, we don't really care anymore about handling the event.
         std::weak_ptr<Tab> weakTabPtr = hostingTab;