When do the virtual methods in GUILayoutEntry get called?

I have debugged codes in the OnGUI code in EditorWindow class and read the blog about unity3d's implementation of IMGUI by Richard Fine.

Following shows two call of OnGUI. Just a glancing summary...

1. First OnGUI:

Code (CSharp):

1.  
2. Event.current.type == EventType.Layout; // True
3. GUILayout.BeginHorizontal(); // Push a GUILayoutGroup to the current GUILayoutCache.
4.     GUILayout.Button("buttonA"); // Add a GUILayoutEntry to the top level GUILayoutGroup's entry list.
5.     GUILayout.Button("buttonB"); // Add a GUILayoutEntry to the top level GUILayoutGroup's entry list.
6.     GUILayout.Button("buttonC"); // Add a GUILayoutEntry to the top level GUILayoutGroup's entry list.
7. GUILayout.EndHorizontal(); // Pop GUILayoutGroup.
8.  

The rect of GUILayoutEntry objects changed between the two calls of OnGUI.

2. Second OnGUI:

Code (CSharp):

1.  
2. Event.current.type == EventType.Repaint; //True
3. GUILayout.BeginHorizontal(); // Push a GUILayoutGroup to the current GUILayoutCache.
4.     GUILayout.Button("buttonA"); // Read the rect of first GUILayoutEntry from the top level GUILayoutGroup's entry list.
5.     GUILayout.Button("buttonB"); // Read the rect of second GUILayoutEntry from the top level GUILayoutGroup's entry list.
6.     GUILayout.Button("buttonC"); // Read the rect of third GUILayoutEntry from the top level GUILayoutGroup's entry list.
7. GUILayout.EndHorizontal(); // Pop GUILayoutGroup from the current GUILayoutCache.
8.  

GUILayoutEntry.rect only changes when GUILayoutEntry.SetHorizontal/SetVertical (and some other special method.) are called.
I want to know when are those four virtual methods(SetHorizontal/SetVertical/CalcWidth/CalcHeight) of GUILayoutEntry called? Immediately after the call of OnGUI when the current event type is EventType.Layout? Are they called inside the internal implementation of Unity3D's C++ code?

@superpig

 

Are you trying to make your own UI?

 

Yes, I have alreay done much basic work now. But there is still much work to do, and this question is one of that.

 

i cant say for sure... but you can look at some of the c# code, if you dig enough through the .net assemblies UnityEngine.dll i think, using ILSpy (google it).

Sorry. Things like what you're asking might not be very well known by general developers.

 

Sure. I have alreay looked into the codes with ILSpy. But find those virtual methods are called nowhere. Maybe they are called by the Unity editor's Window codes. I just want to make things more clear if someone knows about that.

This is why I @superpig.

 

Thank you for pointing that out.