add optional<ImGuiID>dockSpaceIdFromName

   **Warning**: this will work reliably only if layoutCondition = DockingLayoutCondition::ApplicationStart. In other
   cases, the ID may be cached by ImGui himself at the first run, and HelloImGui will *not* know it on subsequent runs!

@see #50

src/hello_imgui/docking_params.h

@@ -5,6 +5,7 @@
 #include <string>
 #include <vector>
 #include <utility>
+#include <optional>
 #include <stdio.h>
 
 namespace HelloImGui
@@ -195,7 +196,10 @@ struct DockableWindow
 
  * `DockableWindow * dockableWindowOfName(const std::string & name)`: returns a pointer to a dockable window
  * `void focusDockableWindow(const std::string& name)`: will focus a dockable window
-
+ * `optional<ImGuiID> dockSpaceIdFromName(const std::string& dockSpaceName)`: may return the ImGuiID corresponding
+   to the dockspace with this name.
+   **Warning**: this will work reliably only if layoutCondition = DockingLayoutCondition::ApplicationStart. In other
+   cases, the ID may be cached by ImGui himself at the first run, and HelloImGui will *not* know it on subsequent runs!
 @@md
  */
 
@@ -217,6 +221,8 @@ struct DockingParams
 
     DockableWindow * dockableWindowOfName(const std::string & name);
     void focusDockableWindow(const std::string& windowName);
+
+    std::optional<ImGuiID> dockSpaceIdFromName(const std::string& dockSpaceName);
 };
 } // namespace HelloImGui
 

src/hello_imgui/hello_imgui_api.md

@@ -553,7 +553,10 @@ _Members:_
 
  * `DockableWindow * dockableWindowOfName(const std::string & name)`: returns a pointer to a dockable window
  * `void focusDockableWindow(const std::string& name)`: will focus a dockable window
-
+ * `optional<ImGuiID> dockSpaceIdFromName(const std::string& dockSpaceName)`: may return the ImGuiID corresponding
+   to the dockspace with this name.
+   **Warning**: this will work reliably only if layoutCondition = DockingLayoutCondition::ApplicationStart. In other
+   cases, the ID may be cached by ImGui himself at the first run, and HelloImGui will *not* know it on subsequent runs!
 
 ---
 

src/hello_imgui/internal/docking_details.cpp

@@ -265,5 +265,13 @@ void DockingParams::focusDockableWindow(const std::string& windowName)
         fprintf(stderr, "focusDockableWindow(%s) failed, window not found!\n", windowName.c_str());
 }
 
+std::optional<ImGuiID> DockingParams::dockSpaceIdFromName(const std::string& dockSpaceName)
+{
+    if (gImGuiSplitIDs.find(dockSpaceName) == gImGuiSplitIDs.end())
+        return std::nullopt;
+    else
+        return gImGuiSplitIDs.at(dockSpaceName);
+}
+
 
 }  // namespace HelloImGui