C++ FArrangedChildren类代码示例

void SSequencerTrackArea::OnArrangeChildren( const FGeometry& AllottedGeometry, FArrangedChildren& ArrangedChildren ) const
{
	for (int32 ChildIndex = 0; ChildIndex < Children.Num(); ++ChildIndex)
	{
		const FTrackAreaSlot& CurChild = Children[ChildIndex];

		const EVisibility ChildVisibility = CurChild.GetWidget()->GetVisibility();
		if (!ArrangedChildren.Accepts(ChildVisibility))
		{
			continue;
		}

		const FMargin Padding(0, CurChild.GetVerticalOffset(), 0, 0);

		AlignmentArrangeResult XResult = AlignChild<Orient_Horizontal>(AllottedGeometry.Size.X, CurChild, Padding, 1.0f, false);
		AlignmentArrangeResult YResult = AlignChild<Orient_Vertical>(AllottedGeometry.Size.Y, CurChild, Padding, 1.0f, false);

		ArrangedChildren.AddWidget(ChildVisibility,
			AllottedGeometry.MakeChild(
				CurChild.GetWidget(),
				FVector2D(XResult.Offset,YResult.Offset),
				FVector2D(XResult.Size, YResult.Size)
			)
		);
	}
}

void SUniformGridPanel::OnArrangeChildren( const FGeometry& AllottedGeometry, FArrangedChildren& ArrangedChildren ) const
{
	if ( Children.Num() > 0 )
	{
		const FVector2D CellSize(AllottedGeometry.Size.X / NumColumns, AllottedGeometry.Size.Y / NumRows);
		const FMargin& CurrentSlotPadding(SlotPadding.Get());
		for ( int32 ChildIndex=0; ChildIndex < Children.Num(); ++ChildIndex )
		{
			const FSlot& Child = Children[ChildIndex];
			const EVisibility ChildVisibility = Child.GetWidget()->GetVisibility();
			if ( ArrangedChildren.Accepts(ChildVisibility) )
			{
				// Do the standard arrangement of elements within a slot
				// Takes care of alignment and padding.
				AlignmentArrangeResult XAxisResult = AlignChild<Orient_Horizontal>(CellSize.X, Child, CurrentSlotPadding);
				AlignmentArrangeResult YAxisResult = AlignChild<Orient_Vertical>(CellSize.Y, Child, CurrentSlotPadding);

				ArrangedChildren.AddWidget(ChildVisibility,
					AllottedGeometry.MakeChild(Child.GetWidget(),
					FVector2D(CellSize.X*Child.Column + XAxisResult.Offset, CellSize.Y*Child.Row + YAxisResult.Offset),
					FVector2D(XAxisResult.Size, YAxisResult.Size)
					));
			}

		}
	}
}

void SAnimationOutlinerView::OnArrangeChildren( const FGeometry& AllottedGeometry, FArrangedChildren& ArrangedChildren ) const
{
	const float Padding = SequencerLayoutConstants::NodePadding;
	const float IndentAmount = SequencerLayoutConstants::IndentAmount;

	float CurrentHeight = 0;
	for (int32 WidgetIndex = 0; WidgetIndex < Children.Num(); ++WidgetIndex)
	{
		const TSharedRef<SAnimationOutlinerTreeNode>& Widget = Children[WidgetIndex];

		EVisibility Visibility = Widget->GetVisibility();
		if( ArrangedChildren.Accepts( Visibility ) )
		{
			const TSharedPtr<const FSequencerDisplayNode>& DisplayNode = Widget->GetDisplayNode();
			// How large to make this node
			float HeightIncrement = DisplayNode->GetNodeHeight();
			// How far to indent the widget
			float WidgetIndentOffset = IndentAmount*DisplayNode->GetTreeLevel();
			// Place the widget at the current height, at the nodes desired size
			ArrangedChildren.AddWidget( 
				Visibility, 
				AllottedGeometry.MakeChild( Widget, FVector2D( WidgetIndentOffset, CurrentHeight ), FVector2D( AllottedGeometry.GetDrawSize().X-WidgetIndentOffset, HeightIncrement ) ) 
				);
		
			// Compute the start height for the next widget
			CurrentHeight += HeightIncrement+Padding;
		}
	}
}

void SScaleBox::OnArrangeChildren( const FGeometry& AllottedGeometry, FArrangedChildren& ArrangedChildren ) const
{
	const EVisibility ChildVisibility = ChildSlot.GetWidget()->GetVisibility();
	if ( ArrangedChildren.Accepts(ChildVisibility) )
	{
		FVector2D DesiredSize = ChildSlot.GetWidget()->GetDesiredSize();

		float FinalScale = 1;

		EStretch::Type CurrentStretch = Stretch.Get();
		EStretchDirection::Type CurrentStretchDirection = StretchDirection.Get();

		if ( DesiredSize.X != 0 && DesiredSize.Y != 0 )
		{
			switch ( CurrentStretch )
			{
			case EStretch::None:
				break;
			case EStretch::Fill:
				DesiredSize = AllottedGeometry.Size;
				break;
			case EStretch::ScaleToFit:
				FinalScale = FMath::Min(AllottedGeometry.Size.X / DesiredSize.X, AllottedGeometry.Size.Y / DesiredSize.Y);
				break;
			case EStretch::ScaleToFill:
				FinalScale = FMath::Max(AllottedGeometry.Size.X / DesiredSize.X, AllottedGeometry.Size.Y / DesiredSize.Y);
				break;
			}

			switch ( CurrentStretchDirection )
			{
			case EStretchDirection::DownOnly:
				FinalScale = FMath::Min(FinalScale, 1.0f);
				break;
			case EStretchDirection::UpOnly:
				FinalScale = FMath::Max(FinalScale, 1.0f);
				break;
			}
		}

		FVector2D FinalOffset(0, 0);

		if ( CurrentStretch != EStretch::Fill )
		{
			const FMargin SlotPadding(ChildSlot.SlotPadding.Get());
			AlignmentArrangeResult XResult = AlignChild<Orient_Horizontal>(AllottedGeometry.Size.X, ChildSlot, SlotPadding, FinalScale, false);
			AlignmentArrangeResult YResult = AlignChild<Orient_Vertical>(AllottedGeometry.Size.Y, ChildSlot, SlotPadding, FinalScale, false);

			FinalOffset = FVector2D(XResult.Offset, YResult.Offset) * ( 1.0f / FinalScale );
		}

		ArrangedChildren.AddWidget(ChildVisibility, AllottedGeometry.MakeChild(
			ChildSlot.GetWidget(),
			FinalOffset,
			DesiredSize,
			FinalScale
		) );
	}
}

void SScrollBarTrack::OnArrangeChildren(const FGeometry& AllottedGeometry, FArrangedChildren& ArrangedChildren) const
{
	const float Width = AllottedGeometry.Size.X;
	const float Height = AllottedGeometry.Size.Y;

	// We only need to show all three children when the thumb is visible, otherwise we only need to show the track
	if (IsNeeded())
	{
		FTrackSizeInfo TrackSizeInfo = this->GetTrackSizeInfo(AllottedGeometry);

		// Arrange top half of the track
		FVector2D ChildSize = (Orientation == Orient_Horizontal)
			? FVector2D(TrackSizeInfo.ThumbStart, Height)
			: FVector2D(Width, TrackSizeInfo.ThumbStart);

		FVector2D ChildPos(0, 0);
		ArrangedChildren.AddWidget(
			AllottedGeometry.MakeChild(Children[TOP_SLOT_INDEX].GetWidget(), ChildPos, ChildSize)
			);

		// Arrange bottom half of the track
		ChildPos = (Orientation == Orient_Horizontal)
			? FVector2D(TrackSizeInfo.GetThumbEnd(), 0)
			: FVector2D(0, TrackSizeInfo.GetThumbEnd());

		ChildSize = (Orientation == Orient_Horizontal)
			? FVector2D(AllottedGeometry.Size.X - TrackSizeInfo.GetThumbEnd(), Height)
			: FVector2D(Width, AllottedGeometry.Size.Y - TrackSizeInfo.GetThumbEnd());

		ArrangedChildren.AddWidget(
			AllottedGeometry.MakeChild(Children[BOTTOM_SLOT_INDEX].GetWidget(), ChildPos, ChildSize)
			);

		// Arrange the thumb
		ChildPos = (Orientation == Orient_Horizontal)
			? FVector2D(TrackSizeInfo.ThumbStart, 0)
			: FVector2D(0, TrackSizeInfo.ThumbStart);

		ChildSize = (Orientation == Orient_Horizontal)
			? FVector2D(TrackSizeInfo.ThumbSize, Height)
			: FVector2D(Width, TrackSizeInfo.ThumbSize);

		ArrangedChildren.AddWidget(
			AllottedGeometry.MakeChild(Children[THUMB_SLOT_INDEX].GetWidget(), ChildPos, ChildSize)
			);
	}
	else
	{
		// No thumb is visible, so just show the top half of the track at the current width/height
		ArrangedChildren.AddWidget(
			AllottedGeometry.MakeChild(Children[TOP_SLOT_INDEX].GetWidget(), FVector2D(0, 0), FVector2D(Width, Height))
			);
	}
}

void SFxWidget::OnArrangeChildren( const FGeometry& AllottedGeometry, FArrangedChildren& ArrangedChildren ) const
{
	const EVisibility MyVisibility = this->GetVisibility();
	if ( ArrangedChildren.Accepts( MyVisibility ) )
	{
		// Only layout scale affects the arranged geometry.
		const FSlateLayoutTransform LayoutTransform(LayoutScale.Get());

		ArrangedChildren.AddWidget( AllottedGeometry.MakeChild(
			this->ChildSlot.GetWidget(),
			TransformVector(Inverse(LayoutTransform), AllottedGeometry.Size),
			LayoutTransform));
	}
}

void SWeakWidget::OnArrangeChildren( const FGeometry& AllottedGeometry, FArrangedChildren& ArrangedChildren ) const
{
	// We just want to show the child that we are presenting. Always stretch it to occupy all of the space.
	TSharedRef<SWidget> MyContent = WeakChild.GetWidget();

	if( MyContent!=SNullWidget::NullWidget && ArrangedChildren.Accepts(MyContent->GetVisibility()) )
	{
		ArrangedChildren.AddWidget( AllottedGeometry.MakeChild(
			MyContent,
			FVector2D(0,0),
			AllottedGeometry.Size
			) );
	}
}

int32 SPanel::PaintArrangedChildren( const FPaintArgs& Args, const FArrangedChildren& ArrangedChildren, const FSlateRect& MyClippingRect, FSlateWindowElementList& OutDrawElements, int32 LayerId, const FWidgetStyle& InWidgetStyle, bool bParentEnabled  ) const
{
	// Because we paint multiple children, we must track the maximum layer id that they produced in case one of our parents
	// wants to an overlay for all of its contents.
	int32 MaxLayerId = LayerId;

	const FPaintArgs NewArgs = Args.WithNewParent(this);

	for (int32 ChildIndex = 0; ChildIndex < ArrangedChildren.Num(); ++ChildIndex)
	{
		const FArrangedWidget& CurWidget = ArrangedChildren[ChildIndex];

		bool bWereOverlapping;
		FSlateRect ChildClipRect = MyClippingRect.IntersectionWith(CurWidget.Geometry.GetClippingRect(), bWereOverlapping);
		
		if ( bWereOverlapping )
		{
			const int32 CurWidgetsMaxLayerId = CurWidget.Widget->Paint(NewArgs, CurWidget.Geometry, ChildClipRect, OutDrawElements, LayerId, InWidgetStyle, ShouldBeEnabled(bParentEnabled));
			MaxLayerId = FMath::Max(MaxLayerId, CurWidgetsMaxLayerId);
		}		
		
	}
	
	return MaxLayerId;
}

void SFlarePlanetaryBox::OnArrangeChildren(const FGeometry& AllottedGeometry, FArrangedChildren& ArrangedChildren) const
{
	const FFlareStyleCatalog& Theme = FFlareStyleSet::GetDefaultTheme();

	for (int32 ChildIndex = 0; ChildIndex < Children.Num(); ++ChildIndex)
	{
		// Get all required data
		const SFlarePlanetaryBox::FSlot& CurChild = Children[ChildIndex];
		const EVisibility ChildVisibility = CurChild.GetWidget()->GetVisibility();
		FVector2D WidgetSize = CurChild.GetWidget()->GetDesiredSize();
		FVector2D Offset = FVector2D::ZeroVector;

		// Child with index 0 is the main body, index 1 is probably the name but we don't care, others are sectors
		if (ChildIndex > 0)
		{
			float X, Y;
			float Angle = (360 / (Children.Num() - 1)) * (ChildIndex - 1) - 90;
			FMath::PolarToCartesian(Radius, FMath::DegreesToRadians(Angle), X, Y);
			Offset = FVector2D(X, Y);

			WidgetSize = FVector2D(CurChild.GetWidget()->GetDesiredSize().X, Theme.SectorButtonHeight);
		}
			
		// Arrange the child
		FVector2D Location = (AllottedGeometry.GetLocalSize() - WidgetSize) / 2 + Offset;
		ArrangedChildren.AddWidget(ChildVisibility, AllottedGeometry.MakeChild(
			CurChild.GetWidget(),
			Location,
			CurChild.GetWidget()->GetDesiredSize()
		));
	}
}

void SDPIScaler::OnArrangeChildren( const FGeometry& AllottedGeometry, FArrangedChildren& ArrangedChildren ) const
{
	const EVisibility MyVisibility = this->GetVisibility();
	if ( ArrangedChildren.Accepts( MyVisibility ) )
	{
		const float MyDPIScale = DPIScale.Get();

		ArrangedChildren.AddWidget( AllottedGeometry.MakeChild(
			this->ChildSlot.GetWidget(),
			FVector2D::ZeroVector,
			AllottedGeometry.Size / MyDPIScale,
			MyDPIScale
		));

	}
}

	virtual void OnArrangeChildren( const FGeometry& AllottedGeometry, FArrangedChildren& ArrangedChildren ) const override
	{
		if (Children.Num() == 0)
		{
			return;
		}

		const float Alpha = 1.f - SlideCurve.GetLerp();
		float PositionSoFar = AllottedGeometry.GetLocalSize().Y + StartSlideOffset*Alpha;

		for (int32 Index = 0; Index < NumSlots(); ++Index)
		{
			const SBoxPanel::FSlot& CurChild = Children[Index];
			const EVisibility ChildVisibility = CurChild.GetWidget()->GetVisibility();

			if (ChildVisibility != EVisibility::Collapsed)
			{
				const FVector2D ChildDesiredSize = CurChild.GetWidget()->GetDesiredSize();

				const FMargin SlotPadding(CurChild.SlotPadding.Get());
				const FVector2D SlotSize(AllottedGeometry.Size.X, ChildDesiredSize.Y + SlotPadding.GetTotalSpaceAlong<Orient_Vertical>());

				const AlignmentArrangeResult XAlignmentResult = AlignChild<Orient_Horizontal>( SlotSize.X, CurChild, SlotPadding );
				const AlignmentArrangeResult YAlignmentResult = AlignChild<Orient_Vertical>( SlotSize.Y, CurChild, SlotPadding );

				ArrangedChildren.AddWidget( ChildVisibility, AllottedGeometry.MakeChild(
					CurChild.GetWidget(),
					FVector2D( XAlignmentResult.Offset, PositionSoFar - SlotSize.Y + YAlignmentResult.Offset ),
					FVector2D( XAlignmentResult.Size, YAlignmentResult.Size )
					));

				PositionSoFar -= SlotSize.Y;
			}
		}
	}

void SZoomPan::OnArrangeChildren(const FGeometry& AllottedGeometry, FArrangedChildren& ArrangedChildren) const
{
	const EVisibility ChildVisibility = ChildSlot.GetWidget()->GetVisibility();
	if ( ArrangedChildren.Accepts(ChildVisibility) )
	{
		const FMargin SlotPadding(ChildSlot.SlotPadding.Get());
		AlignmentArrangeResult XResult = AlignChild<Orient_Horizontal>(AllottedGeometry.Size.X, ChildSlot, SlotPadding, 1);
		AlignmentArrangeResult YResult = AlignChild<Orient_Vertical>(AllottedGeometry.Size.Y, ChildSlot, SlotPadding, 1);

		ArrangedChildren.AddWidget( ChildVisibility, AllottedGeometry.MakeChild(
				ChildSlot.GetWidget(),
				FVector2D(XResult.Offset, YResult.Offset) - ViewOffset.Get(),
				ChildSlot.GetWidget()->GetDesiredSize(),
				ZoomAmount.Get()
		) );
	}
}

void FSlateWidgetRun::ArrangeChildren( const TSharedRef< ILayoutBlock >& Block, const FGeometry& AllottedGeometry, FArrangedChildren& ArrangedChildren ) const
{
	// The block size and offset values are pre-scaled, so we need to account for that when converting the block offsets into paint geometry
	const float InverseScale = Inverse(AllottedGeometry.Scale);

	ArrangedChildren.AddWidget(
		AllottedGeometry.MakeChild(Info.Widget, TransformVector(InverseScale, Block->GetSize()), FSlateLayoutTransform(TransformPoint(InverseScale, Block->GetLocationOffset())))
		);
}

void SBox::OnArrangeChildren( const FGeometry& AllottedGeometry, FArrangedChildren& ArrangedChildren ) const
{
	const EVisibility& MyCurrentVisibility = this->GetVisibility();
	if ( ArrangedChildren.Accepts( MyCurrentVisibility ) )
	{
		const FMargin SlotPadding(ChildSlot.SlotPadding.Get());
		AlignmentArrangeResult XAlignmentResult = AlignChild<Orient_Horizontal>( AllottedGeometry.Size.X, ChildSlot, SlotPadding );
		AlignmentArrangeResult YAlignmentResult = AlignChild<Orient_Vertical>( AllottedGeometry.Size.Y, ChildSlot, SlotPadding );

		ArrangedChildren.AddWidget(
			AllottedGeometry.MakeChild(
				ChildSlot.GetWidget(),
				FVector2D(XAlignmentResult.Offset, YAlignmentResult.Offset),
				FVector2D(XAlignmentResult.Size, YAlignmentResult.Size)
			)
		);
	}
}

void SDockingTabWell::OnArrangeChildren( const FGeometry& AllottedGeometry, FArrangedChildren& ArrangedChildren ) const
{
	// The specialized TabWell is dedicated to arranging tabs.
	// Tabs have uniform sizing (all tabs the same size).
	// TabWell also ignores widget visibilit, as it is not really
	// relevant.


	// The tab that is being dragged by the user, if any.
	TSharedPtr<SDockTab> TabBeingDragged = TabBeingDraggedPtr;
		
	const int32 NumChildren = Tabs.Num();

	// Tabs have a uniform size.
	const FVector2D ChildSize = ComputeChildSize(AllottedGeometry);


	const float DraggedChildCenter = ChildBeingDraggedOffset + ChildSize.X / 2;

	// Arrange all the tabs left to right.
	float XOffset = 0;
	for( int32 TabIndex=0; TabIndex < NumChildren; ++TabIndex )
	{
		const TSharedRef<SDockTab> CurTab = Tabs[TabIndex];
		const float ChildWidthWithOverlap = ChildSize.X - CurTab->GetOverlapWidth();

		// Is this spot reserved from the tab that is being dragged?
		if ( TabBeingDragged.IsValid() && XOffset <= DraggedChildCenter && DraggedChildCenter < (XOffset + ChildWidthWithOverlap) )
		{
			// if so, leave some room to signify that this is where the dragged tab would end up
			XOffset += ChildWidthWithOverlap;
		}

		ArrangedChildren.AddWidget( AllottedGeometry.MakeChild(CurTab, FVector2D(XOffset, 0), ChildSize) );

		XOffset += ChildWidthWithOverlap;
	}
		
	// Arrange the tab currently being dragged by the user, if any
	if ( TabBeingDragged.IsValid() )
	{
		ArrangedChildren.AddWidget( AllottedGeometry.MakeChild( TabBeingDragged.ToSharedRef(), FVector2D(ChildBeingDraggedOffset,0), ChildSize) );
	}
}