Unreal Engine 4.8 Slate font outline hack - SlateTextRun.cpp

--- //depot/Projects/UnrealEngine/Main/Engine/Source/Runtime/Slate/Private/Framework/Text/SlateTextRun.cpp  2015-03-22 07:56:30.000000000 1100
+++ C:\Local\Projects\UnrealEngine\Main\Engine\Source\Runtime\Slate\Private\Framework\Text\SlateTextRun.cpp 2015-03-22 07:56:30.000000000 1100
@@ -6,6 +6,16 @@

 #include "SlateTextRun.h"

+FVector2D GetShadowOffsetAndOutlineThickness(const FVector2D& StyleShadowOffset, float& OutlineThicknessOut, uint32& OutlineDirectionsOut)
+{
+   FVector2D ShadowOffset(StyleShadowOffset);
+   OutlineThicknessOut = FMath::RoundToInt(StyleShadowOffset.X * 0.001f);
+   ShadowOffset.X -= OutlineThicknessOut * 1000.f;
+   OutlineDirectionsOut = FMath::RoundToInt(StyleShadowOffset.Y * 0.001f);
+   ShadowOffset.Y -= OutlineDirectionsOut * 1000.f;
+   return ShadowOffset;
+}
+
 TSharedRef< FSlateTextRun > FSlateTextRun::Create( const FRunInfo& InRunInfo, const TSharedRef< const FString >& InText, const FTextBlockStyle& Style )
 {
    return MakeShareable( new FSlateTextRun( InRunInfo, InText, Style ) );
@@ -28,19 +38,29 @@

 int16 FSlateTextRun::GetBaseLine( float Scale ) const
 {
+   float OutlineThickness;
+   uint32 OutlineDirections;
+   FVector2D ShadowOffset = GetShadowOffsetAndOutlineThickness(Style.ShadowOffset, OutlineThickness, OutlineDirections);
    const TSharedRef< FSlateFontMeasure > FontMeasure = FSlateApplication::Get().GetRenderer()->GetFontMeasureService();
-   return FontMeasure->GetBaseline( Style.Font, Scale ) - FMath::Min(0.0f, Style.ShadowOffset.Y * Scale);
+   return FontMeasure->GetBaseline( Style.Font, Scale ) - FMath::Min(0.0f, ShadowOffset.Y * Scale);
 }

 int16 FSlateTextRun::GetMaxHeight( float Scale ) const
 {
+   float OutlineThickness;
+   uint32 OutlineDirections;
+   FVector2D ShadowOffset = GetShadowOffsetAndOutlineThickness(Style.ShadowOffset, OutlineThickness, OutlineDirections);
    const TSharedRef< FSlateFontMeasure > FontMeasure = FSlateApplication::Get().GetRenderer()->GetFontMeasureService();
-   return FontMeasure->GetMaxCharacterHeight( Style.Font, Scale ) + FMath::Abs(Style.ShadowOffset.Y * Scale);
+   return FontMeasure->GetMaxCharacterHeight( Style.Font, Scale ) + FMath::Abs(ShadowOffset.Y * Scale);
 }

 FVector2D FSlateTextRun::Measure( int32 BeginIndex, int32 EndIndex, float Scale ) const
 {
-   const FVector2D ShadowOffsetToApply((EndIndex == Range.EndIndex) ? FMath::Abs(Style.ShadowOffset.X * Scale) : 0.0f, FMath::Abs(Style.ShadowOffset.Y * Scale));
+   float OutlineThickness;
+   uint32 OutlineDirections;
+   FVector2D ShadowOffset = GetShadowOffsetAndOutlineThickness(Style.ShadowOffset, OutlineThickness, OutlineDirections);
+
+   const FVector2D ShadowOffsetToApply((EndIndex == Range.EndIndex) ? FMath::Abs(ShadowOffset.X * Scale) : 0.0f, FMath::Abs(ShadowOffset.Y * Scale));

    if ( EndIndex - BeginIndex == 0 )
    {
@@ -73,7 +93,11 @@
    const FSlateRect ClippingRect = AllottedGeometry.GetClippingRect().IntersectionWith(MyClippingRect);
    const ESlateDrawEffect::Type DrawEffects = bParentEnabled ? ESlateDrawEffect::None : ESlateDrawEffect::DisabledEffect;

-   const bool ShouldDropShadow = Style.ShadowOffset.Size() > 0;
+   float OutlineThickness;
+   uint32 OutlineDirections;
+   FVector2D ShadowOffset = GetShadowOffsetAndOutlineThickness(Style.ShadowOffset, OutlineThickness, OutlineDirections);
+
+   const bool ShouldDropShadow = ShadowOffset.Size() > 0;
    const FVector2D BlockLocationOffset = Block->GetLocationOffset();
    const FTextRange BlockRange = Block->GetTextRange();

@@ -82,14 +106,40 @@

    // A negative shadow offset should be applied as a positive offset to the text to avoid clipping issues
    const FVector2D DrawShadowOffset(
-       (Style.ShadowOffset.X > 0.0f) ? Style.ShadowOffset.X * AllottedGeometry.Scale : 0.0f,
-       (Style.ShadowOffset.Y > 0.0f) ? Style.ShadowOffset.Y * AllottedGeometry.Scale : 0.0f
+       (ShadowOffset.X > 0.0f) ? ShadowOffset.X * AllottedGeometry.Scale : 0.0f,
+       (ShadowOffset.Y > 0.0f) ? ShadowOffset.Y * AllottedGeometry.Scale : 0.0f
        );
    const FVector2D DrawTextOffset(
-       (Style.ShadowOffset.X < 0.0f) ? -Style.ShadowOffset.X * AllottedGeometry.Scale : 0.0f,
-       (Style.ShadowOffset.Y < 0.0f) ? -Style.ShadowOffset.Y * AllottedGeometry.Scale : 0.0f
+       (ShadowOffset.X < 0.0f) ? -ShadowOffset.X * AllottedGeometry.Scale : 0.0f,
+       (ShadowOffset.Y < 0.0f) ? -ShadowOffset.Y * AllottedGeometry.Scale : 0.0f
        );

+   // Draw the outline
+   if (OutlineThickness > 0.f)
+   {
+       FSlateRect OutlineClippingRect(ClippingRect.Left - OutlineThickness, ClippingRect.Top - OutlineThickness, ClippingRect.Right + OutlineThickness, ClippingRect.Bottom + OutlineThickness);
+       FVector2D OutlineOffset;
+       float AngleStep = 360.f / (float)OutlineDirections;
+       FVector2D OutlineDirection(0.f, OutlineThickness * AllottedGeometry.Scale);
+       for (uint32 i = 0; i < OutlineDirections; ++i)
+       {
+           OutlineOffset = OutlineDirection.GetRotated(AngleStep * i);
+           FSlateDrawElement::MakeText(
+               OutDrawElements,
+               ++LayerId,
+               AllottedGeometry.ToPaintGeometry(TransformVector(InverseScale, Block->GetSize()), FSlateLayoutTransform(TransformPoint(InverseScale, Block->GetLocationOffset() + DrawTextOffset + OutlineOffset))),
+               Text.Get(),
+               BlockRange.BeginIndex,
+               BlockRange.EndIndex,
+               Style.Font,
+               OutlineClippingRect,
+               DrawEffects,
+               InWidgetStyle.GetColorAndOpacityTint() * Style.ShadowColorAndOpacity
+               );
+
+       }
+   }
+
    // Draw the optional shadow
    if ( ShouldDropShadow )
    {