fix(new_editor/docking): darken overlay and use full center preview

new_editor/app/Composition/EditorShellRuntimeRendering.cpp

@@ -6,6 +6,7 @@
 
 namespace XCEngine::UI::Editor::App::RuntimeSupport {
 
+using ::XCEngine::UI::UIColor;
 using ::XCEngine::UI::UIDrawList;
 
 UIEditorShellComposeModel BuildShellComposeModelFromFrame(
@@ -47,6 +48,49 @@ void AppendShellPopups(
     }
 }
 
+UIEditorShellComposeFrame BuildShellComposeFrameWithoutDockPreview(
+    const UIEditorShellComposeFrame& frame) {
+    UIEditorShellComposeFrame copy = frame;
+    copy.workspaceFrame.dockHostLayout.dropPreview = {};
+    return copy;
+}
+
+UIRect ResolveDockPreviewOverlayRect(const UIEditorShellComposeFrame& frame) {
+    const auto& dropPreview = frame.workspaceFrame.dockHostLayout.dropPreview;
+    UIRect previewRect = dropPreview.previewRect;
+    if (dropPreview.placement != UIEditorWorkspaceDockPlacement::Center) {
+        return previewRect;
+    }
+
+    for (const Widgets::UIEditorDockHostTabStackLayout& tabStack :
+         frame.workspaceFrame.dockHostLayout.tabStacks) {
+        if (tabStack.nodeId == dropPreview.targetNodeId) {
+            return tabStack.bounds;
+        }
+    }
+
+    return previewRect;
+}
+
+void AppendDockPreviewOverlay(
+    UIDrawList& drawList,
+    const UIEditorShellComposeFrame& frame) {
+    const auto& dropPreview = frame.workspaceFrame.dockHostLayout.dropPreview;
+    if (!dropPreview.visible) {
+        return;
+    }
+
+    const UIRect previewRect = ResolveDockPreviewOverlayRect(frame);
+    if (previewRect.width <= 0.0f || previewRect.height <= 0.0f) {
+        return;
+    }
+
+    static const UIColor kDropPreviewFillColor(0.56f, 0.56f, 0.56f, 0.06f);
+    static const UIColor kDropPreviewBorderColor(0.68f, 0.68f, 0.68f, 0.26f);
+    drawList.AddFilledRect(previewRect, kDropPreviewFillColor);
+    drawList.AddRectOutline(previewRect, kDropPreviewBorderColor, 1.0f);
+}
+
 } // namespace XCEngine::UI::Editor::App::RuntimeSupport
 
 namespace XCEngine::UI::Editor::App {
@@ -64,9 +108,11 @@ void EditorShellRuntime::Append(UIDrawList& drawList) const {
     const auto& palette = ResolveUIEditorShellInteractionPalette();
     const UIEditorShellComposeModel shellComposeModel =
         BuildShellComposeModelFromFrame(m_shellFrame);
+    const UIEditorShellComposeFrame shellComposeFrame =
+        BuildShellComposeFrameWithoutDockPreview(m_shellFrame.shellFrame);
     AppendUIEditorShellCompose(
         drawList,
-        m_shellFrame.shellFrame,
+        shellComposeFrame,
         shellComposeModel,
         m_shellInteractionState.composeState,
         palette.shellPalette,
@@ -75,6 +121,7 @@ void EditorShellRuntime::Append(UIDrawList& drawList) const {
     m_hierarchyPanel.Append(drawList);
     m_inspectorPanel.Append(drawList);
     m_projectPanel.Append(drawList);
+    AppendDockPreviewOverlay(drawList, m_shellFrame.shellFrame);
     AppendShellPopups(drawList, m_shellFrame, palette, metrics);
 }