Add native scrolling to new editor tree views

new_editor/include/XCEditor/Collections/UIEditorTreeView.h

@@ -1,5 +1,7 @@
 #pragma once
 
+#include <XCEditor/Collections/UIEditorScrollView.h>
+
 #include <XCEngine/UI/DrawData.h>
 #include <XCEngine/UI/Widgets/UIExpansionModel.h>
 #include <XCEngine/UI/Widgets/UISelectionModel.h>
@@ -32,6 +34,7 @@ struct UIEditorTreeViewItem {
 struct UIEditorTreeViewState {
     std::string hoveredItemId = {};
     bool focused = false;
+    UIEditorScrollViewState scrollViewState = {};
 };
 
 struct UIEditorTreeViewMetrics {
@@ -48,6 +51,7 @@ struct UIEditorTreeViewMetrics {
     float cornerRounding = 6.0f;
     float borderThickness = 1.0f;
     float focusedBorderThickness = 2.0f;
+    UIEditorScrollViewMetrics scrollViewMetrics = {};
 };
 
 struct UIEditorTreeViewPalette {
@@ -67,10 +71,12 @@ struct UIEditorTreeViewPalette {
         ::XCEngine::UI::UIColor(0.62f, 0.62f, 0.62f, 1.0f);
     ::XCEngine::UI::UIColor textColor =
         ::XCEngine::UI::UIColor(0.92f, 0.92f, 0.92f, 1.0f);
+    UIEditorScrollViewPalette scrollViewPalette = {};
 };
 
 struct UIEditorTreeViewLayout {
     ::XCEngine::UI::UIRect bounds = {};
+    UIEditorScrollViewLayout scrollViewLayout = {};
     std::vector<std::size_t> visibleItemIndices = {};
     std::vector<::XCEngine::UI::UIRect> rowRects = {};
     std::vector<::XCEngine::UI::UIRect> disclosureRects = {};
@@ -111,11 +117,17 @@ std::size_t FindUIEditorTreeViewFirstVisibleChildItemIndex(
     const ::XCEngine::UI::Widgets::UIExpansionModel& expansionModel,
     std::size_t itemIndex);
 
+float MeasureUIEditorTreeViewContentHeight(
+    const std::vector<UIEditorTreeViewItem>& items,
+    const ::XCEngine::UI::Widgets::UIExpansionModel& expansionModel,
+    const UIEditorTreeViewMetrics& metrics = {});
+
 UIEditorTreeViewLayout BuildUIEditorTreeViewLayout(
     const ::XCEngine::UI::UIRect& bounds,
     const std::vector<UIEditorTreeViewItem>& items,
     const ::XCEngine::UI::Widgets::UIExpansionModel& expansionModel,
-    const UIEditorTreeViewMetrics& metrics = {});
+    const UIEditorTreeViewMetrics& metrics = {},
+    float verticalOffset = 0.0f);
 
 UIEditorTreeViewHitTarget HitTestUIEditorTreeView(
     const UIEditorTreeViewLayout& layout,