editor/panels/scene_hierarchy_panel.hpp

@@ -7,7 +7,7 @@
 
 class SceneHierarchyPanel : public sophia::Panel {
  public:
-  SceneHierarchyPanel() : Panel{{.name = "Scene Hierarchy"}} {}
+  SceneHierarchyPanel() : Panel{{.name = "Scene Hierarchy", .locked = true}} {}
 
   void onUpdate(const sophia::FrameInfo& frameInfo) override;
 

engine/include/sophia/ui/panel.hpp

@@ -1,5 +1,7 @@
 #pragma once
 
+#include <imgui.h>
+
 #include <glm/glm.hpp>
 #include <optional>
 #include <sophia/frame_info.hpp>
@@ -11,9 +13,11 @@ namespace sophia {
 class Panel {
  public:
   struct Config {
-    std::string name;
+    const std::string name;
+
+    ImGuiWindowFlags windowFlags = ImGuiWindowFlags_None;
+    ImGuiDockNodeFlags dockNodeFlags = ImGuiDockNodeFlags_None;
 
-    // Locked panels can't be moved, resized, docked, collapsed or closed.
     bool locked = false;
     bool closable = true;
 
@@ -21,20 +25,27 @@ class Panel {
     // every frame when locked.
     glm::vec2 size{0.0f, 0.0f};
     std::optional<glm::vec2> position;
+
+    ImGuiWindowFlags getWindowFlags() const;
+    ImGuiDockNodeFlags getDockNodeFlags() const;
+    bool hasCloseButton() const;
+    ImGuiCond getPlacementCond() const;
   };
 
   Panel(const Panel&) = delete;
   Panel& operator=(const Panel&) = delete;
 
   Panel(Panel&&) noexcept = default;
-  Panel& operator=(Panel&&) noexcept = default;
+  Panel& operator=(Panel&&) = delete;
 
   explicit Panel(Config config) : config{std::move(config)} {}
   virtual ~Panel() = default;
 
-  // Owns the ImGui window: Begin, onUpdate, End.
   void draw(const FrameInfo& frameInfo);
 
+  Config& getConfig() { return config; }
+  const Config& getConfig() const { return config; }
+
   const std::string& getName() const { return config.name; }
   bool isLocked() const { return config.locked; }
 
@@ -43,7 +54,6 @@ class Panel {
   void toggleVisible() { this->visible = !this->visible; }
 
  protected:
-  // Draw the panel's contents; the window is already open.
   virtual void onUpdate(const FrameInfo& frameInfo) = 0;
 
   bool visible = true;

engine/src/ui/panel.cpp

@@ -1,18 +1,43 @@
 #include <imgui.h>
+#include <imgui_internal.h>
 
 #include <sophia/ui/panel.hpp>
 
 namespace sophia {
 
-void Panel::draw(const FrameInfo& frameInfo) {
-  ImGuiWindowFlags flags = ImGuiWindowFlags_None;
-  if (config.locked) {
+ImGuiWindowFlags Panel::Config::getWindowFlags() const {
+  ImGuiWindowFlags flags = windowFlags;
+  if (locked) {
     flags |= ImGuiWindowFlags_NoMove | ImGuiWindowFlags_NoResize |
-             ImGuiWindowFlags_NoDocking | ImGuiWindowFlags_NoCollapse;
+             ImGuiWindowFlags_NoCollapse;
   }
+  return flags;
+}
 
-  const ImGuiCond cond =
-      config.locked ? ImGuiCond_Always : ImGuiCond_FirstUseEver;
+ImGuiDockNodeFlags Panel::Config::getDockNodeFlags() const {
+  ImGuiDockNodeFlags flags = dockNodeFlags;
+  if (locked) {
+    flags |= static_cast<int>(ImGuiDockNodeFlags_NoUndocking) |
+             static_cast<int>(ImGuiDockNodeFlags_NoResize) |
+             static_cast<int>(ImGuiDockNodeFlags_NoCloseButton) |
+             static_cast<int>(ImGuiDockNodeFlags_NoDockingOverMe) |
+             static_cast<int>(ImGuiDockNodeFlags_NoDockingSplit);
+  }
+  return flags;
+}
+
+bool Panel::Config::hasCloseButton() const { return closable && !locked; }
+
+ImGuiCond Panel::Config::getPlacementCond() const {
+  return locked ? ImGuiCond_Always : ImGuiCond_FirstUseEver;
+}
+
+void Panel::draw(const FrameInfo& frameInfo) {
+  ImGuiWindowClass windowClass;
+  windowClass.DockNodeFlagsOverrideSet = config.getDockNodeFlags();
+  ImGui::SetNextWindowClass(&windowClass);
+
+  const ImGuiCond cond = config.getPlacementCond();
   if (config.size.x > 0.0f || config.size.y > 0.0f) {
     ImGui::SetNextWindowSize(ImVec2(config.size.x, config.size.y), cond);
   }
@@ -22,8 +47,8 @@ void Panel::draw(const FrameInfo& frameInfo) {
   }
 
   bool open = true;
-  const bool showCloseButton = config.closable && !config.locked;
-  ImGui::Begin(config.name.c_str(), showCloseButton ? &open : nullptr, flags);
+  ImGui::Begin(config.name.c_str(), config.hasCloseButton() ? &open : nullptr,
+               config.getWindowFlags());
   onUpdate(frameInfo);
   ImGui::End();