Working on CommonUI conversion. Need to stop using SetAnchorsInViewport as way to position widgets, so now implementing new thing using GridPanels.

Config/DefaultEngine.ini

@@ -82,3 +82,6 @@ UIScaleCurve=(EditorCurveData=(Keys=((Time=480.000000,Value=0.444000),(Time=720.
 +CollisionChannelRedirects=(OldName="PawnMovement",NewName="Pawn")
 +CollisionChannelRedirects=(OldName="Clickable",NewName="LookAtDetection")
 
+[/Script/Engine.Engine]
+GameViewportClientClassName=/Script/CommonUI.CommonGameViewportClient
+

Source/Integration/UtilityLibrary.cpp

@@ -6,6 +6,8 @@
 #include "EnhancedInputSubsystems.h"
 #include "Kismet/KismetSystemLibrary.h"
 #include "Kismet/GameplayStatics.h"
+#include "Blueprint/UserWidget.h"
+#include "Components/GridPanel.h"
 
 
 #define LOCTEXT_NAMESPACE "Luprex Utility"
@@ -146,3 +148,64 @@ bool UlxUtilityLibrary::LineTraceThroughPixel(const APlayerController* PlayerCon
 	HitResult.Init();
 	return false;
 }
+
+void UlxUtilityLibrary::SetPositionOfGridPanelMiddleCell(UGridPanel *GridPanel, FVector2D UpperLeftXY, FVector2D LowerRightXY)
+{
+	if ((GridPanel == nullptr) || (GridPanel->ColumnFill.Num() != 3) || (GridPanel->RowFill.Num() != 3))
+	{
+		UE_LOG(LogBlueprint, Error, TEXT("SetPositionOfGridPanelMiddleCell only works on 3x3 GridPanels."));
+		return;
+	}
+
+	if ((LowerRightXY.X < UpperLeftXY.X) || (LowerRightXY.Y < UpperLeftXY.Y))
+	{
+		UE_LOG(LogBlueprint, Error, TEXT("LowerRightXY must be greater than or equal to UpperLeftXY"));
+		return;
+	}
+
+	UpperLeftXY.X = FMath::Clamp(UpperLeftXY.X, 0.0f, 1.0f);
+	UpperLeftXY.Y = FMath::Clamp(UpperLeftXY.Y, 0.0f, 1.0f);
+	LowerRightXY.X = FMath::Clamp(LowerRightXY.X, 0.0f, 1.0f);
+	LowerRightXY.Y = FMath::Clamp(LowerRightXY.Y, 0.0f, 1.0f);
+
+	GridPanel->SetRowFill(0, UpperLeftXY.Y);
+	GridPanel->SetRowFill(1, LowerRightXY.Y - UpperLeftXY.Y);
+	GridPanel->SetRowFill(2, 1.0 - LowerRightXY.Y);
+
+	GridPanel->SetColumnFill(0, UpperLeftXY.X);
+	GridPanel->SetColumnFill(1, LowerRightXY.X - UpperLeftXY.X);
+	GridPanel->SetColumnFill(2, 1.0 - LowerRightXY.X);
+}
+
+void UlxUtilityLibrary::GetPositionOfGridPanelMiddleCell(UGridPanel *GridPanel, FVector2D &UpperLeftXY, FVector2D &LowerRightXY)
+{
+	TArray<float> &Col = GridPanel->ColumnFill;
+	TArray<float> &Row = GridPanel->RowFill;
+
+	// Set default return value for error situations.
+	UpperLeftXY.X = 0.0;
+	LowerRightXY.X = 1.0;
+	UpperLeftXY.Y = 0.0;
+	LowerRightXY.Y = 1.0;
+
+	if ((GridPanel == nullptr) || (Row.Num() != 3) || (Col.Num() != 3))
+	{
+		UE_LOG(LogBlueprint, Error, TEXT("SetPositionOfGridPanelMiddleCell only works on 3x3 GridPanels."));
+		return;
+	}
+
+	double TotalX = Col[0] + Col[1] + Col[2];
+	double TotalY = Row[0] + Row[1] + Row[2];
+	
+	if (TotalX > 0)
+	{
+		UpperLeftXY.X = Col[0] / TotalX;
+		LowerRightXY.X = (Col[0] + Col[1]) / TotalX;
+	}
+
+	if (TotalY > 0)
+	{
+		UpperLeftXY.Y = Row[0] / TotalY;
+		LowerRightXY.Y = (Row[0] + Row[1]) / TotalY;
+	}
+}

Source/Integration/UtilityLibrary.h

@@ -85,4 +85,51 @@ public:
 			FVector2D PixelXY, double MaxDistanceFromCamera,
 			ETraceTypeQuery TraceChannel, bool bTraceComplex, EDrawDebugTrace::Type DrawDebugType, bool bIgnorePlayerPawn,
 			const TArray<AActor*>& ActorsToIgnore, FHitResult& HitResult);
+
+	// Set Position of GridPanel Middle Cell
+	//
+	// Sometimes, you want to specify the position of a widget, and you
+	// don't want to specify the position in slate units, instead, you
+	// want to specify the position using fractions: ie, (0,0) is the
+	// upper left corner of the screen, and (1,1) is the lower-right corner.
+	//
+	// One way to accomplish this is to put your widget in the middle cell
+	// of a 3x3 GridPanel.  Then, you can position it by adjusting the grid
+	// fill rules.  This utility routine can do the math necessary to
+	// correctly populate those fill rules.
+	//
+	// This routine must be passed a 3x3 GridPanel.  This will reposition
+	// the middle cell.  You must specify the upper-left and lower-right
+	// corners of the middle cell as fractions between (0,0) and (1,1).
+	//
+	// Be aware that if the content of a grid cell overflows the amount of
+	// space allocated for it, then the grid will adjust to make room.
+	// But that will mean that the grid is no longer faithful to the 
+	// positions specified in its fill rules.  One way to ensure that the
+	// grid remains faithful to its fill rules is to put an Overlay
+	// into the GridPanel cell, then put -1000 padding into the
+	// Overlay's GridPanel slot, then put +1000 padding into the Overlay
+	// slot.  The two paddings cancel each other out, leaving the item in
+	// the Overlay at the originally-intended position.  But if the item
+	// in the overlay overflows, it doesn't cause the Grid to deform.
+	// Instead, the item exceeds the bounds of the grid cell, but it leaves
+	// the grid cell where it belongs.
+	// 
+	UFUNCTION(BlueprintCallable, Category="Widget")
+	static void SetPositionOfGridPanelMiddleCell(UGridPanel *GridPanel, FVector2D UpperLeftXY, FVector2D LowerRightXY);
+
+	// Get Position of GridPanel Middle Cell
+	//
+	// The routine must be passed a 3x3 GridPanel.  This will return the
+	// position of the middle cell of the gridpanel, expressed on a scale
+	// from (0,0) to (1,1).
+	// 
+	// The numbers returned by this routine are based entirely on the
+	// GridPanel fill rules.  If an item in the grid is overflowing its
+	// allocated space, causing the grid to deform, then that won't be
+	// reflected in the output of this routine.
+	//
+	UFUNCTION(BlueprintPure, Category="Widget")
+	static void GetPositionOfGridPanelMiddleCell(UGridPanel *GridPanel, FVector2D &UpperLeftXY, FVector2D &LowerRightXY);
+
 };

luprex/lua/login.lua

@@ -31,7 +31,11 @@ end
 
 function engio.getlookat()
     local class = tangible.getclass(tangible.place())
-    if class == nil then return end
+
+    -- if the tangible is not of any class, return empty string.
+    if class == nil then
+        return ""
+    end
 
     -- if the class has a function 'lookhotkeys', then the correct
     -- look-at widget is 'hotkeys'.  We're going to automatically 
@@ -47,5 +51,8 @@ function engio.getlookat()
     if class.getlookat ~= nil then
         return class.getlookat()
     end
+
+    -- by default, return the empty string.
+    return ""
 end