Snap to character grid when resizing window

src/cascadia/TerminalApp/AppLogic.cpp

@@ -443,6 +443,13 @@ namespace winrt::TerminalApp::implementation
         return _settings->GlobalSettings().GetShowTabsInTitlebar();
     }
 
+    // Method Description:
+    // - See Pane::CalcSnappedDimension
+    float AppLogic::CalcSnappedDimension(const bool widthOrHeight, const float dimension) const
+    {
+        return _root->CalcSnappedDimension(widthOrHeight, dimension);
+    }
+
     // Method Description:
     // - Attempt to load the settings. If we fail for any reason, returns an error.
     // Return Value:

src/cascadia/TerminalApp/AppLogic.h

@@ -38,6 +38,7 @@ namespace winrt::TerminalApp::implementation
         winrt::Windows::UI::Xaml::ElementTheme GetRequestedTheme();
         LaunchMode GetLaunchMode();
         bool GetShowTabsInTitlebar();
+        float CalcSnappedDimension(const bool widthOrHeight, const float dimension) const;
 
         Windows::UI::Xaml::UIElement GetRoot() noexcept;
 

src/cascadia/TerminalApp/AppLogic.idl

@@ -35,6 +35,7 @@ namespace TerminalApp
         Windows.UI.Xaml.ElementTheme GetRequestedTheme();
         LaunchMode GetLaunchMode();
         Boolean GetShowTabsInTitlebar();
+        Single CalcSnappedDimension(Boolean widthOrHeight, Single dimension);
         void TitlebarClicked();
         void WindowCloseButtonClicked();
 

src/cascadia/TerminalApp/Pane.LayoutSizeNode.cpp

@@ -0,0 +1,73 @@
+// Copyright (c) Microsoft Corporation.
+// Licensed under the MIT license.
+
+#include "pch.h"
+#include "Pane.h"
+
+Pane::LayoutSizeNode::LayoutSizeNode(const float minSize) :
+    size{ minSize },
+    isMinimumSize{ true },
+    firstChild{ nullptr },
+    secondChild{ nullptr },
+    nextFirstChild{ nullptr },
+    nextSecondChild{ nullptr }
+{
+}
+
+Pane::LayoutSizeNode::LayoutSizeNode(const LayoutSizeNode& other) :
+    size{ other.size },
+    isMinimumSize{ other.isMinimumSize },
+    firstChild{ other.firstChild ? std::make_unique<LayoutSizeNode>(*other.firstChild) : nullptr },
+    secondChild{ other.secondChild ? std::make_unique<LayoutSizeNode>(*other.secondChild) : nullptr },
+    nextFirstChild{ other.nextFirstChild ? std::make_unique<LayoutSizeNode>(*other.nextFirstChild) : nullptr },
+    nextSecondChild{ other.nextSecondChild ? std::make_unique<LayoutSizeNode>(*other.nextSecondChild) : nullptr }
+{
+}
+
+// Method Description:
+// - Makes sure that this node and all its descendants equal the supplied node.
+//   This may be more efficient that copy construction since it will reuse its
+//   allocated children.
+// Arguments:
+// - other: Node to take the values from.
+// Return Value:
+// - itself
+Pane::LayoutSizeNode& Pane::LayoutSizeNode::operator=(const LayoutSizeNode& other)
+{
+    size = other.size;
+    isMinimumSize = other.isMinimumSize;
+
+    _AssignChildNode(firstChild, other.firstChild.get());
+    _AssignChildNode(secondChild, other.secondChild.get());
+    _AssignChildNode(nextFirstChild, other.nextFirstChild.get());
+    _AssignChildNode(nextSecondChild, other.nextSecondChild.get());
+
+    return *this;
+}
+
+// Method Description:
+// - Performs assignment operation on a single child node reusing
+// - current one if present.
+// Arguments:
+// - nodeField: Reference to our field holding concerned node.
+// - other: Node to take the values from.
+// Return Value:
+// - <none>
+void Pane::LayoutSizeNode::_AssignChildNode(std::unique_ptr<LayoutSizeNode>& nodeField, const LayoutSizeNode* const newNode)
+{
+    if (newNode)
+    {
+        if (nodeField)
+        {
+            *nodeField = *newNode;
+        }
+        else
+        {
+            nodeField = std::make_unique<LayoutSizeNode>(*newNode);
+        }
+    }
+    else
+    {
+        nodeField.release();
+    }
+}