Editor Viewports

FViewport::Draw

It seems that the root of any viewport drawing is this function.

About viewport clients

From this post I found out that:

• SEditorViewport is a slate widget to host your viewport client
• FEditorViewportClient is the actual viewport class that handle the input and rendering.

Viewport clients have the same FCommonViewportClient base class.

Here are the various viewport client types depending on what is visible:

• Level viewport: FLevelEditorViewportClient (parent is FEditorViewportClient)
• Blueprint Viewport: FSCSEditorViewportClient (parent is FEditorViewportClient)
• Animation Viewport FAnimationViewportClient (parent is FEditorViewportClient)

Viewports

Get latest opened editor(s)

In this example we are only getting one editor window, but you could get all recently focused (activated) editor windows.

UAssetEditorSubsystem* AssetEditorSubsystem = GEditor->GetEditorSubsystem<UAssetEditorSubsystem>();  
TArray<UObject*> EditedAssets = AssetEditorSubsystem->GetAllEditedAssets();  
TArray<IAssetEditorInstance*> OpenedEditors;  
  
for (UObject* EditedAsset : EditedAssets)  
{
	OpenedEditors.Add(AssetEditorSubsystem->FindEditorForAsset(EditedAsset, false));  
}
 
IAssetEditorInstance* FocusedEditor = nullptr;  
float MaxLastActivationTime = 0.5;  
 
for (IAssetEditorInstance* OpenedEditor : OpenedEditors)  
{
	if (OpenedEditor && OpenedEditor->GetLastActivationTime() > MaxLastActivationTime)
	{
		MaxLastActivationTime = OpenedEditor->GetLastActivationTime();
		FocusedEditor = OpenedEditor;
	}
}  
  
FBlueprintEditor* BlueprintEditor = static_cast<FBlueprintEditor*>(FocusedEditor);

Level Editor Viewport

To get the viewport of the current level you can use GEditor->GetActiveViewport()->GetClient()

Blueprint Editor Viewport

The Blueprint Viewport is from FSCSEditorViewportClient. As soon as one of them is visible, FSCSEditorViewportClient::Draw is called (See FViewport::Draw).