Add XCUI editor collection primitives and stack rollback

engine/include/XCEngine/UI/Widgets/UIEditorCollectionPrimitives.h

@@ -0,0 +1,41 @@
+#pragma once
+
+#include <XCEngine/UI/Style/Theme.h>
+
+#include <cstdint>
+#include <string_view>
+
+namespace XCEngine {
+namespace UI {
+namespace Widgets {
+
+enum class UIEditorCollectionPrimitiveKind : std::uint8_t {
+    None = 0,
+    ScrollView,
+    TreeView,
+    TreeItem,
+    ListView,
+    ListItem,
+    PropertySection,
+    FieldRow
+};
+
+UIEditorCollectionPrimitiveKind ClassifyUIEditorCollectionPrimitive(std::string_view tagName);
+bool IsUIEditorCollectionPrimitiveContainer(UIEditorCollectionPrimitiveKind kind);
+bool UsesUIEditorCollectionPrimitiveColumnLayout(UIEditorCollectionPrimitiveKind kind);
+bool IsUIEditorCollectionPrimitiveHoverable(UIEditorCollectionPrimitiveKind kind);
+bool DoesUIEditorCollectionPrimitiveClipChildren(UIEditorCollectionPrimitiveKind kind);
+float ResolveUIEditorCollectionPrimitivePadding(
+    UIEditorCollectionPrimitiveKind kind,
+    const Style::UITheme& theme);
+float ResolveUIEditorCollectionPrimitiveDefaultHeight(
+    UIEditorCollectionPrimitiveKind kind,
+    const Style::UITheme& theme);
+float ResolveUIEditorCollectionPrimitiveIndent(
+    UIEditorCollectionPrimitiveKind kind,
+    const Style::UITheme& theme,
+    float indentLevel);
+
+} // namespace Widgets
+} // namespace UI
+} // namespace XCEngine

engine/src/UI/Runtime/UIScreenStackController.cpp

@@ -82,11 +82,27 @@ bool UIScreenStackController::ReplaceTop(
         return PushScreen(asset, options) != 0;
     }
 
-    if (!Pop()) {
+    if (m_system == nullptr) {
         return false;
     }
 
-    return PushScreen(asset, options) != 0;
+    const UIScreenStackEntry previousTop = m_entries.back();
+    const UIScreenLayerId replacementLayerId = m_system->PushScreen(asset, options);
+    if (replacementLayerId == 0) {
+        return false;
+    }
+
+    if (!m_system->RemoveLayer(previousTop.layerId)) {
+        m_system->RemoveLayer(replacementLayerId);
+        return false;
+    }
+
+    UIScreenStackEntry replacementEntry = {};
+    replacementEntry.layerId = replacementLayerId;
+    replacementEntry.asset = asset;
+    replacementEntry.options = options;
+    m_entries.back() = std::move(replacementEntry);
+    return true;
 }
 
 bool UIScreenStackController::Pop() {

engine/src/UI/Widgets/UIEditorCollectionPrimitives.cpp

@@ -0,0 +1,114 @@
+#include <XCEngine/UI/Widgets/UIEditorCollectionPrimitives.h>
+
+namespace XCEngine {
+namespace UI {
+namespace Widgets {
+
+namespace {
+
+float ResolveFloatToken(
+    const Style::UITheme& theme,
+    const char* tokenName,
+    float fallbackValue) {
+    const Style::UITokenResolveResult result =
+        theme.ResolveToken(tokenName, Style::UIStyleValueType::Float);
+    if (result.status != Style::UITokenResolveStatus::Resolved) {
+        return fallbackValue;
+    }
+
+    const float* value = result.value.TryGetFloat();
+    return value != nullptr ? *value : fallbackValue;
+}
+
+} // namespace
+
+UIEditorCollectionPrimitiveKind ClassifyUIEditorCollectionPrimitive(std::string_view tagName) {
+    if (tagName == "ScrollView") {
+        return UIEditorCollectionPrimitiveKind::ScrollView;
+    }
+    if (tagName == "TreeView") {
+        return UIEditorCollectionPrimitiveKind::TreeView;
+    }
+    if (tagName == "TreeItem") {
+        return UIEditorCollectionPrimitiveKind::TreeItem;
+    }
+    if (tagName == "ListView") {
+        return UIEditorCollectionPrimitiveKind::ListView;
+    }
+    if (tagName == "ListItem") {
+        return UIEditorCollectionPrimitiveKind::ListItem;
+    }
+    if (tagName == "PropertySection") {
+        return UIEditorCollectionPrimitiveKind::PropertySection;
+    }
+    if (tagName == "FieldRow") {
+        return UIEditorCollectionPrimitiveKind::FieldRow;
+    }
+
+    return UIEditorCollectionPrimitiveKind::None;
+}
+
+bool IsUIEditorCollectionPrimitiveContainer(UIEditorCollectionPrimitiveKind kind) {
+    return kind == UIEditorCollectionPrimitiveKind::ScrollView ||
+        kind == UIEditorCollectionPrimitiveKind::TreeView ||
+        kind == UIEditorCollectionPrimitiveKind::ListView ||
+        kind == UIEditorCollectionPrimitiveKind::PropertySection;
+}
+
+bool UsesUIEditorCollectionPrimitiveColumnLayout(UIEditorCollectionPrimitiveKind kind) {
+    return kind == UIEditorCollectionPrimitiveKind::TreeView ||
+        kind == UIEditorCollectionPrimitiveKind::ListView ||
+        kind == UIEditorCollectionPrimitiveKind::PropertySection;
+}
+
+bool IsUIEditorCollectionPrimitiveHoverable(UIEditorCollectionPrimitiveKind kind) {
+    return kind == UIEditorCollectionPrimitiveKind::TreeItem ||
+        kind == UIEditorCollectionPrimitiveKind::ListItem ||
+        kind == UIEditorCollectionPrimitiveKind::FieldRow;
+}
+
+bool DoesUIEditorCollectionPrimitiveClipChildren(UIEditorCollectionPrimitiveKind kind) {
+    return kind == UIEditorCollectionPrimitiveKind::ScrollView ||
+        kind == UIEditorCollectionPrimitiveKind::TreeView ||
+        kind == UIEditorCollectionPrimitiveKind::ListView;
+}
+
+float ResolveUIEditorCollectionPrimitivePadding(
+    UIEditorCollectionPrimitiveKind kind,
+    const Style::UITheme& theme) {
+    return kind == UIEditorCollectionPrimitiveKind::TreeView ||
+            kind == UIEditorCollectionPrimitiveKind::ListView ||
+            kind == UIEditorCollectionPrimitiveKind::PropertySection
+        ? ResolveFloatToken(theme, "space.cardInset", 12.0f)
+        : 0.0f;
+}
+
+float ResolveUIEditorCollectionPrimitiveDefaultHeight(
+    UIEditorCollectionPrimitiveKind kind,
+    const Style::UITheme& theme) {
+    switch (kind) {
+    case UIEditorCollectionPrimitiveKind::TreeItem:
+        return ResolveFloatToken(theme, "size.treeItemHeight", 28.0f);
+    case UIEditorCollectionPrimitiveKind::ListItem:
+        return ResolveFloatToken(theme, "size.listItemHeight", 60.0f);
+    case UIEditorCollectionPrimitiveKind::FieldRow:
+        return ResolveFloatToken(theme, "size.fieldRowHeight", 32.0f);
+    case UIEditorCollectionPrimitiveKind::PropertySection:
+        return ResolveFloatToken(theme, "size.propertySectionHeight", 148.0f);
+    default:
+        return 0.0f;
+    }
+}
+
+float ResolveUIEditorCollectionPrimitiveIndent(
+    UIEditorCollectionPrimitiveKind kind,
+    const Style::UITheme& theme,
+    float indentLevel) {
+    return kind == UIEditorCollectionPrimitiveKind::TreeItem
+        ? indentLevel * ResolveFloatToken(theme, "size.treeIndent", 18.0f)
+        : 0.0f;
+}
+
+} // namespace Widgets
+} // namespace UI
+} // namespace XCEngine