UnrealEngineUWP/Engine/Source/Editor/Sequencer/Private/TimeSliderController.cpp

// Copyright 1998-2015 Epic Games, Inc. All Rights Reserved.

#include "SequencerPrivatePCH.h"
#include "TimeSliderController.h"

#define LOCTEXT_NAMESPACE "TimeSlider"

namespace ScrubConstants
{
	/** The minimum amount of pixels between each major ticks on the widget */
	const int32 MinPixelsPerDisplayTick = 5;

	/**The smallest number of units between between major tick marks */
	const float MinDisplayTickSpacing = 0.001f;

	/**The fraction of the current view range to scroll per unit delta  */
	const float ScrollPanFraction = 0.1f;
}


/** Utility struct for converting between scrub range space and local/absolute screen space */
struct FScrubRangeToScreen
{
	FVector2D WidgetSize;

	TRange<float> ViewInput;
	float ViewInputRange;
	float PixelsPerInput;

	FScrubRangeToScreen(TRange<float> InViewInput, const FVector2D& InWidgetSize )
	{
		WidgetSize = InWidgetSize;

		ViewInput = InViewInput;
		ViewInputRange = ViewInput.Size<float>();
		PixelsPerInput = ViewInputRange > 0 ? ( WidgetSize.X / ViewInputRange ) : 0;
	}

	/** Local Widget Space -> Curve Input domain. */
	float LocalXToInput(float ScreenX) const
	{
		float LocalX = ScreenX;
		return (LocalX/PixelsPerInput) + ViewInput.GetLowerBoundValue();
	}

	/** Curve Input domain -> local Widget Space */
	float InputToLocalX(float Input) const
	{
		return (Input - ViewInput.GetLowerBoundValue()) * PixelsPerInput;
	}
};


/**
 * Gets the the next spacing value in the series 
 * to determine a good spacing value
 * E.g, .001,.005,.010,.050,.100,.500,1.000,etc
 */
static float GetNextSpacing( uint32 CurrentStep )
{
	if(CurrentStep & 0x01) 
	{
		// Odd numbers
		return FMath::Pow( 10.f, 0.5f*((float)(CurrentStep-1)) + 1.f );
	}
	else 
	{
		// Even numbers
		return 0.5f * FMath::Pow( 10.f, 0.5f*((float)(CurrentStep)) + 1.f );
	}
}

/**
 * Determines the optimal spacing between tick marks in the slider for a given pixel density
 * Increments until a minimum amount of slate units specified by MinTick is reached
 * 
 * @param InPixelsPerInput	The density of pixels between each input
 * @param MinTick			The minimum slate units per tick allowed
 * @param MinTickSpacing	The minimum tick spacing in time units allowed
 * @return the optimal spacing in time units
 */
float DetermineOptimalSpacing( float InPixelsPerInput, uint32 MinTick, float MinTickSpacing )
{
	uint32 CurStep = 0;

	// Start with the smallest spacing
	float Spacing = MinTickSpacing;

	if (InPixelsPerInput > 0)
	{
		while( Spacing * InPixelsPerInput < MinTick )
		{
			Spacing = MinTickSpacing * GetNextSpacing( CurStep );
			CurStep++;
		}
	}

	return Spacing;
}


FSequencerTimeSliderController::FSequencerTimeSliderController( const FTimeSliderArgs& InArgs )
	: TimeSliderArgs( InArgs )
	, DistanceDragged( 0.0f )
	, bDraggingScrubber( false )
	, bPanning( false )
{
	ScrubHandleUp = FEditorStyle::GetBrush( TEXT( "Sequencer.Timeline.ScrubHandleUp" ) ); 
	ScrubHandleDown = FEditorStyle::GetBrush( TEXT( "Sequencer.Timeline.ScrubHandleDown" ) );
}

struct FDrawTickArgs
{
	/** Geometry of the area */
	FGeometry AllottedGeometry;
	/** Clipping rect of the area */
	FSlateRect ClippingRect;
	/** Color of each tick */
	FLinearColor TickColor;
	/** Offset in Y where to start the tick */
	float TickOffset;
	/** Height in of major ticks */
	float MajorTickHeight;
	/** Start layer for elements */
	int32 StartLayer;
	/** Draw effects to apply */
	ESlateDrawEffect::Type DrawEffects;
	/** Whether or not to only draw major ticks */
	bool bOnlyDrawMajorTicks;
	/** Whether or not to mirror labels */
	bool bMirrorLabels;
	
};

void FSequencerTimeSliderController::DrawTicks( FSlateWindowElementList& OutDrawElements, const struct FScrubRangeToScreen& RangeToScreen, FDrawTickArgs& InArgs ) const
{
	const float Spacing = DetermineOptimalSpacing( RangeToScreen.PixelsPerInput, ScrubConstants::MinPixelsPerDisplayTick, ScrubConstants::MinDisplayTickSpacing );

	// Sub divisions
	// @todo Sequencer may need more robust calculation
	const int32 Divider = 10;
	// For slightly larger halfway tick mark
	const int32 HalfDivider = Divider / 2;
	// Find out where to start from
	int32 OffsetNum = FMath::FloorToInt(RangeToScreen.ViewInput.GetLowerBoundValue() / Spacing);
	
	FSlateFontInfo SmallLayoutFont( FPaths::EngineContentDir() / TEXT("Slate/Fonts/Roboto-Regular.ttf"), 8 );

	TArray<FVector2D> LinePoints;
	LinePoints.AddUninitialized(2);

	float Seconds = 0;
	while( (Seconds = OffsetNum*Spacing) < RangeToScreen.ViewInput.GetUpperBoundValue() )
	{
		// X position local to start of the widget area
		float XPos = RangeToScreen.InputToLocalX( Seconds );
		uint32 AbsOffsetNum = FMath::Abs(OffsetNum);

		if ( AbsOffsetNum % Divider == 0 )
		{
			FVector2D Offset( XPos, InArgs.TickOffset );
			FVector2D TickSize( 0.0f, InArgs.MajorTickHeight );

			LinePoints[0] = FVector2D( 0.0f,1.0f);
			LinePoints[1] = TickSize;

			// lines should not need anti-aliasing
			const bool bAntiAliasLines = false;

			// Draw each tick mark
			FSlateDrawElement::MakeLines(
				OutDrawElements,
				InArgs.StartLayer,
				InArgs.AllottedGeometry.ToPaintGeometry( Offset, TickSize ),
				LinePoints,
				InArgs.ClippingRect,
				InArgs.DrawEffects,
				InArgs.TickColor,
				bAntiAliasLines
				);

			if( !InArgs.bOnlyDrawMajorTicks )
			{
				FString FrameString = Spacing == ScrubConstants::MinDisplayTickSpacing ? FString::Printf( TEXT("%.3f"), Seconds ) : FString::Printf( TEXT("%.2f"), Seconds );

				// Space the text between the tick mark but slightly above
				const TSharedRef< FSlateFontMeasure > FontMeasureService = FSlateApplication::Get().GetRenderer()->GetFontMeasureService();
				FVector2D TextSize = FontMeasureService->Measure(FrameString, SmallLayoutFont);
				FVector2D TextOffset( XPos-(TextSize.X*0.5f), InArgs.bMirrorLabels ? TextSize.Y :  FMath::Abs( InArgs.AllottedGeometry.Size.Y - (InArgs.MajorTickHeight+TextSize.Y) ) );

				FSlateDrawElement::MakeText(
					OutDrawElements,
					InArgs.StartLayer+1, 
					InArgs.AllottedGeometry.ToPaintGeometry( TextOffset, TextSize ), 
					FrameString, 
					SmallLayoutFont, 
					InArgs.ClippingRect, 
					InArgs.DrawEffects,
					InArgs.TickColor 
				);
			}
		}
		else if( !InArgs.bOnlyDrawMajorTicks )
		{
			// Compute the size of each tick mark.  If we are half way between to visible values display a slightly larger tick mark
			const float MinorTickHeight = AbsOffsetNum % HalfDivider == 0 ? 7.0f : 4.0f;

			FVector2D Offset(XPos, InArgs.bMirrorLabels ? 0.0f : FMath::Abs( InArgs.AllottedGeometry.Size.Y - MinorTickHeight ) );
			FVector2D TickSize(0.0f, MinorTickHeight);

			LinePoints[0] = FVector2D(0.0f,1.0f);
			LinePoints[1] = TickSize;

			const bool bAntiAlias = false;
			// Draw each sub mark
			FSlateDrawElement::MakeLines(
				OutDrawElements,
				InArgs.StartLayer,
				InArgs.AllottedGeometry.ToPaintGeometry( Offset, TickSize ),
				LinePoints,
				InArgs.ClippingRect,
				InArgs.DrawEffects,
				InArgs.TickColor,
				bAntiAlias
			);
		}
		// Advance to next tick mark
		++OffsetNum;
	}
}


int32 FSequencerTimeSliderController::OnPaintTimeSlider( bool bMirrorLabels, const FGeometry& AllottedGeometry, const FSlateRect& MyClippingRect, FSlateWindowElementList& OutDrawElements, int32 LayerId, const FWidgetStyle& InWidgetStyle, bool bParentEnabled ) const
{
	const bool bEnabled = bParentEnabled;
	const ESlateDrawEffect::Type DrawEffects = bEnabled ? ESlateDrawEffect::None : ESlateDrawEffect::DisabledEffect;

	TRange<float> LocalViewRange = TimeSliderArgs.ViewRange.Get();
	const float LocalViewRangeMin = LocalViewRange.GetLowerBoundValue();
	const float LocalViewRangeMax = LocalViewRange.GetUpperBoundValue();
	const float LocalSequenceLength = LocalViewRangeMax-LocalViewRangeMin;
	
	FVector2D Scale = FVector2D(1.0f,1.0f);
	if ( LocalSequenceLength > 0)
	{
		FScrubRangeToScreen RangeToScreen( LocalViewRange, AllottedGeometry.Size );
	
		const float MajorTickHeight = 9.0f;
	
		FDrawTickArgs Args;
		Args.AllottedGeometry = AllottedGeometry;
		Args.bMirrorLabels = bMirrorLabels;
		Args.bOnlyDrawMajorTicks = false;
		Args.TickColor = FLinearColor::White;
		Args.ClippingRect = MyClippingRect;
		Args.DrawEffects = DrawEffects;
		Args.StartLayer = LayerId;
		Args.TickOffset = bMirrorLabels ? 0.0f : FMath::Abs( AllottedGeometry.Size.Y - MajorTickHeight );
		Args.MajorTickHeight = MajorTickHeight;

		DrawTicks( OutDrawElements, RangeToScreen, Args );

		const float HandleSize = 13.0f;
		float HalfSize = FMath::CeilToFloat(HandleSize/2.0f);

		// Draw the scrub handle
		const float XPos = RangeToScreen.InputToLocalX( TimeSliderArgs.ScrubPosition.Get() );

		// Should draw above the text
		const int32 ArrowLayer = LayerId + 2;
		FPaintGeometry MyGeometry =	AllottedGeometry.ToPaintGeometry( FVector2D( XPos-HalfSize, 0 ), FVector2D( HandleSize, AllottedGeometry.Size.Y ) );
		FLinearColor ScrubColor = InWidgetStyle.GetColorAndOpacityTint();

		// @todo Sequencer this color should be specified in the style
		ScrubColor.A = ScrubColor.A*0.5f;
		ScrubColor.B *= 0.1f;
		ScrubColor.G *= 0.2f;
		FSlateDrawElement::MakeBox( 
			OutDrawElements,
			ArrowLayer, 
			MyGeometry,
			bMirrorLabels ? ScrubHandleUp : ScrubHandleDown,
			MyClippingRect, 
			DrawEffects, 
			ScrubColor
			);

		return ArrowLayer;
	}

	return LayerId;
}

FReply FSequencerTimeSliderController::OnMouseButtonDown( TSharedRef<SWidget> WidgetOwner, const FGeometry& MyGeometry, const FPointerEvent& MouseEvent )
{
	bool bHandleLeftMouseButton = MouseEvent.GetEffectingButton() == EKeys::LeftMouseButton;
	bool bHandleRightMouseButton = MouseEvent.GetEffectingButton() == EKeys::RightMouseButton && TimeSliderArgs.AllowZoom;
	
	DistanceDragged = 0;

	if ( bHandleLeftMouseButton )
	{
		return FReply::Handled().CaptureMouse( WidgetOwner ).PreventThrottling();
	}
	else if ( bHandleRightMouseButton )
	{
		// Always capture mouse if we left or right click on the widget
		return FReply::Handled().CaptureMouse( WidgetOwner );
	}

	return FReply::Unhandled();
}

FReply FSequencerTimeSliderController::OnMouseButtonUp( TSharedRef<SWidget> WidgetOwner, const FGeometry& MyGeometry, const FPointerEvent& MouseEvent )
{
	bool bHandleLeftMouseButton = MouseEvent.GetEffectingButton() == EKeys::LeftMouseButton && WidgetOwner->HasMouseCapture();
	bool bHandleRightMouseButton = MouseEvent.GetEffectingButton() == EKeys::RightMouseButton && WidgetOwner->HasMouseCapture() && TimeSliderArgs.AllowZoom ;
	
	if ( bHandleRightMouseButton )
	{
		if (!bPanning)
		{
			// return unhandled in case our parent wants to use our right mouse button to open a context menu
			return FReply::Unhandled().ReleaseMouseCapture();
		}
		
		bPanning = false;
		
		return FReply::Handled().ReleaseMouseCapture();
	}
	else if ( bHandleLeftMouseButton )
	{
		if( bDraggingScrubber )
		{
			TimeSliderArgs.OnEndScrubberMovement.ExecuteIfBound();
		}
		else
		{
			FScrubRangeToScreen RangeToScreen( TimeSliderArgs.ViewRange.Get(), MyGeometry.Size );
			FVector2D CursorPos = MyGeometry.AbsoluteToLocal(MouseEvent.GetLastScreenSpacePosition());
			float NewValue = RangeToScreen.LocalXToInput(CursorPos.X);

			if ( TimeSliderArgs.Settings->GetIsSnapEnabled() && TimeSliderArgs.Settings->GetSnapPlayTimeToInterval() )
			{
				NewValue = TimeSliderArgs.Settings->SnapTimeToInterval( NewValue );
			}

			CommitScrubPosition( NewValue, /*bIsScrubbing=*/false );
		}

		bDraggingScrubber = false;
		return FReply::Handled().ReleaseMouseCapture();

	}

	return FReply::Unhandled();
}

FReply FSequencerTimeSliderController::OnMouseMove( TSharedRef<SWidget> WidgetOwner, const FGeometry& MyGeometry, const FPointerEvent& MouseEvent )
{
	if ( WidgetOwner->HasMouseCapture() )
	{
		if (MouseEvent.IsMouseButtonDown( EKeys::RightMouseButton ))
		{
			if (!bPanning)
			{
				DistanceDragged += FMath::Abs( MouseEvent.GetCursorDelta().X );
				if ( DistanceDragged > FSlateApplication::Get().GetDragTriggerDistance() )
				{
					bPanning = true;
				}
			}
			else
			{
				TRange<float> LocalViewRange = TimeSliderArgs.ViewRange.Get();
				float LocalViewRangeMin = LocalViewRange.GetLowerBoundValue();
				float LocalViewRangeMax = LocalViewRange.GetUpperBoundValue();

				FScrubRangeToScreen ScaleInfo( LocalViewRange, MyGeometry.Size );
				FVector2D ScreenDelta = MouseEvent.GetCursorDelta();
				FVector2D InputDelta;
				InputDelta.X = ScreenDelta.X/ScaleInfo.PixelsPerInput;

				float NewViewOutputMin = LocalViewRangeMin - InputDelta.X;
				float NewViewOutputMax = LocalViewRangeMax - InputDelta.X;

				SetViewRange(NewViewOutputMin, NewViewOutputMax, EViewRangeInterpolation::Immediate);
			}
		}
		else if (MouseEvent.IsMouseButtonDown( EKeys::LeftMouseButton ))
		{
			if ( !bDraggingScrubber )
			{
				DistanceDragged += FMath::Abs( MouseEvent.GetCursorDelta().X );
				if ( DistanceDragged > FSlateApplication::Get().GetDragTriggerDistance() )
				{
					bDraggingScrubber = true;
					TimeSliderArgs.OnBeginScrubberMovement.ExecuteIfBound();
				}
			}
			else
			{
				FScrubRangeToScreen RangeToScreen( TimeSliderArgs.ViewRange.Get(), MyGeometry.Size );
				FVector2D CursorPos = MyGeometry.AbsoluteToLocal( MouseEvent.GetLastScreenSpacePosition() );
				float NewValue = RangeToScreen.LocalXToInput( CursorPos.X );

				if ( TimeSliderArgs.Settings->GetIsSnapEnabled() && TimeSliderArgs.Settings->GetSnapPlayTimeToInterval() )
				{
					NewValue = TimeSliderArgs.Settings->SnapTimeToInterval(NewValue);
				}

				CommitScrubPosition( NewValue, /*bIsScrubbing=*/true );
			}
		}
		return FReply::Handled();
	}

	return FReply::Unhandled();
}

void FSequencerTimeSliderController::CommitScrubPosition( float NewValue, bool bIsScrubbing )
{
	// Manage the scrub position ourselves if its not bound to a delegate
	if ( !TimeSliderArgs.ScrubPosition.IsBound() )
	{
		TimeSliderArgs.ScrubPosition.Set( NewValue );
	}

	TimeSliderArgs.OnScrubPositionChanged.ExecuteIfBound( NewValue, bIsScrubbing );
}

FReply FSequencerTimeSliderController::OnMouseWheel( TSharedRef<SWidget> WidgetOwner, const FGeometry& MyGeometry, const FPointerEvent& MouseEvent )
{
	TOptional<TRange<float>> NewTargetRange;

	float MouseFractionX = MyGeometry.AbsoluteToLocal(MouseEvent.GetScreenSpacePosition()).X / MyGeometry.GetLocalSize().X;
	if ( TimeSliderArgs.AllowZoom && (MouseEvent.IsLeftControlDown() || MouseEvent.IsRightControlDown()) )
	{
		const float ZoomDelta = -0.2f * MouseEvent.GetWheelDelta();
		if (ZoomByDelta(ZoomDelta, MouseFractionX))
		{
			return FReply::Handled();
		}
	}
	else if (MouseEvent.IsLeftShiftDown() || MouseEvent.IsRightShiftDown())
	{
		PanByDelta(-MouseEvent.GetWheelDelta());
		return FReply::Handled();
	}
	
	return FReply::Unhandled();
}

int32 FSequencerTimeSliderController::OnPaintSectionView( const FGeometry& AllottedGeometry, const FSlateRect& MyClippingRect, FSlateWindowElementList& OutDrawElements, int32 LayerId, bool bEnabled, bool bDisplayTickLines, bool bDisplayScrubPosition  ) const
{
	const ESlateDrawEffect::Type DrawEffects = bEnabled ? ESlateDrawEffect::None : ESlateDrawEffect::DisabledEffect;

	TRange<float> LocalViewRange = TimeSliderArgs.ViewRange.Get();
	float LocalScrubPosition = TimeSliderArgs.ScrubPosition.Get();

	float ViewRange = LocalViewRange.Size<float>();
	float PixelsPerInput = ViewRange > 0 ? AllottedGeometry.Size.X / ViewRange : 0;
	float LinePos =  (LocalScrubPosition - LocalViewRange.GetLowerBoundValue()) * PixelsPerInput;

	FScrubRangeToScreen RangeToScreen( LocalViewRange, AllottedGeometry.Size );

	if( bDisplayTickLines )
	{
		// Draw major tick lines in the section area
		FDrawTickArgs Args;
		Args.AllottedGeometry = AllottedGeometry;
		Args.bMirrorLabels = false;
		Args.bOnlyDrawMajorTicks = true;
		Args.TickColor = FLinearColor( 0.3f, 0.3f, 0.3f, 0.3f );
		Args.ClippingRect = MyClippingRect;
		Args.DrawEffects = DrawEffects;
		// Draw major ticks under sections
		Args.StartLayer = LayerId-1;
		// Draw the tick the entire height of the section area
		Args.TickOffset = 0.0f;
		Args.MajorTickHeight = AllottedGeometry.Size.Y;

		DrawTicks( OutDrawElements, RangeToScreen, Args );
	}

	if( bDisplayScrubPosition )
	{
		// Draw a line for the scrub position
		TArray<FVector2D> LinePoints;
		LinePoints.AddUninitialized(2);
		LinePoints[0] = FVector2D( 0.0f, 0.0f );
		LinePoints[1] = FVector2D( 0.0f, FMath::RoundToFloat( AllottedGeometry.Size.Y ) );

		FSlateDrawElement::MakeLines(
			OutDrawElements,
			LayerId+1,
			AllottedGeometry.ToPaintGeometry( FVector2D(LinePos, 0.0f ), FVector2D(1.0f,1.0f) ),
			LinePoints,
			MyClippingRect,
			DrawEffects,
			FLinearColor::White,
			false
			);
	}

	return LayerId;
}

void FSequencerTimeSliderController::SetViewRange( float NewRangeMin, float NewRangeMax, EViewRangeInterpolation Interpolation )
{
	TOptional<float> LocalClampMin = TimeSliderArgs.ClampMin.Get();
	TOptional<float> LocalClampMax = TimeSliderArgs.ClampMax.Get();

	// Clamp the range if clamp values are set
	if ( LocalClampMin.IsSet() && NewRangeMin < LocalClampMin.GetValue() )
	{
		NewRangeMin = LocalClampMin.GetValue();
	}
	
	if ( LocalClampMax.IsSet() && NewRangeMax > LocalClampMax.GetValue() )
	{
		NewRangeMax = LocalClampMax.GetValue();
	}

	const TRange<float> NewRange(NewRangeMin, NewRangeMax);

	TimeSliderArgs.OnViewRangeChanged.ExecuteIfBound( NewRange, Interpolation );

	if( !TimeSliderArgs.ViewRange.IsBound() )
	{	
		// The  output is not bound to a delegate so we'll manage the value ourselves (no animation)
		TimeSliderArgs.ViewRange.Set( NewRange );
	}
}

bool FSequencerTimeSliderController::ZoomByDelta( float InDelta, float MousePositionFraction )
{
	TRange<float> LocalViewRange = TimeSliderArgs.ViewRange.Get().GetAnimationTarget();
	float LocalViewRangeMax = LocalViewRange.GetUpperBoundValue();
	float LocalViewRangeMin = LocalViewRange.GetLowerBoundValue();
	const float OutputViewSize = LocalViewRangeMax - LocalViewRangeMin;
	const float OutputChange = OutputViewSize * InDelta;

	float NewViewOutputMin = LocalViewRangeMin - (OutputChange * MousePositionFraction);
	float NewViewOutputMax = LocalViewRangeMax + (OutputChange * (1.f - MousePositionFraction));

	if( FMath::Abs( OutputChange ) > 0.01f && NewViewOutputMin < NewViewOutputMax )
	{
		SetViewRange(NewViewOutputMin, NewViewOutputMax, EViewRangeInterpolation::Animated);
		return true;
	}

	return false;
}

void FSequencerTimeSliderController::PanByDelta( float InDelta )
{
	TRange<float> LocalViewRange = TimeSliderArgs.ViewRange.Get().GetAnimationTarget();

	float CurrentMin = LocalViewRange.GetLowerBoundValue();
	float CurrentMax = LocalViewRange.GetUpperBoundValue();

	// Adjust the delta to be a percentage of the current range
	InDelta *= ScrubConstants::ScrollPanFraction * (CurrentMax - CurrentMin);

	SetViewRange(CurrentMin + InDelta, CurrentMax + InDelta, EViewRangeInterpolation::Animated);
}


#undef LOCTEXT_NAMESPACE