SColorSpectrum.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "CoreMinimal.h"
#include "Misc/Attribute.h"
#include "Input/Reply.h"
#include "Widgets/DeclarativeSyntaxSupport.h"
#include "Widgets/SLeafWidget.h"
#include "Framework/SlateDelegates.h"
 
class FPaintArgs;
class FSlateWindowElementList;
struct FSlateBrush;
 
class SColorSpectrum
    : public SLeafWidget
{
public:
 
    SLATE_BEGIN_ARGS(SColorSpectrum)
        : _SelectedColor()
        , _OnMouseCaptureBegin()
        , _OnMouseCaptureEnd()
        , _OnValueChanged()
        , _CtrlMultiplier(0.1f)
    { }
    
        SLATE_ATTRIBUTE(FLinearColor, SelectedColor)
        
        
        SLATE_EVENT(FSimpleDelegate, OnMouseCaptureBegin)
 
        
        SLATE_EVENT(FSimpleDelegate, OnMouseCaptureEnd)
 
        
        SLATE_EVENT(FOnLinearColorValueChanged, OnValueChanged)
 
        
        SLATE_ATTRIBUTE(float, CtrlMultiplier)
 
    SLATE_END_ARGS()
    
public:
    SLATE_API SColorSpectrum();
    SLATE_API virtual ~SColorSpectrum();
 
    SLATE_API void Construct( const FArguments& InArgs );
 
public:
 
    // SWidget overrides
 
    SLATE_API virtual FVector2D ComputeDesiredSize(float) const override;
    SLATE_API virtual FReply OnMouseButtonDoubleClick( const FGeometry& InMyGeometry, const FPointerEvent& InMouseEvent ) override;
    SLATE_API virtual FReply OnMouseButtonDown( const FGeometry& MyGeometry, const FPointerEvent& MouseEvent ) override;
    SLATE_API virtual FReply OnMouseButtonUp( const FGeometry& MyGeometry, const FPointerEvent& MouseEvent ) override;
    SLATE_API virtual FReply OnMouseMove( const FGeometry& MyGeometry, const FPointerEvent& MouseEvent ) override;
    SLATE_API virtual int32 OnPaint( const FPaintArgs& Args, const FGeometry& AllottedGeometry, const FSlateRect& MyCullingRect, FSlateWindowElementList& OutDrawElements, int32 LayerId, const FWidgetStyle& InWidgetStyle, bool bParentEnabled ) const override;
    SLATE_API virtual FCursorReply OnCursorQuery(const FGeometry& MyGeometry, const FPointerEvent& CursorEvent) const override;
 
protected:
 
    SLATE_API FVector2D CalcRelativeSelectedPosition( ) const;
 
    SLATE_API void ProcessMouseAction(const FGeometry& MyGeometry, const FPointerEvent& MouseEvent);
 
private:
 
    // The color spectrum image to show.
    const FSlateBrush* Image;
    
    // The current color selected by the user.
    TSlateAttribute<FLinearColor, EInvalidateWidgetReason::Paint> SelectedColor;
 
    // Mouse sensitivity multiplier to use when dragging the selector on the color spectrum, applied when the ctrl modifier key is pressed
    TAttribute<float> CtrlMultiplier;
 
    // The color selector image to show.
    const FSlateBrush* SelectorImage;
 
    // Whether the user is dragging the slider
    bool bDragging = false;
 
    // Cached mouse position to restore after dragging.
    FVector2f LastSpectrumPosition;
 
private:
 
    // Holds a delegate that is executed when the mouse is pressed and a capture begins.
    FSimpleDelegate OnMouseCaptureBegin;
 
    // Holds a delegate that is executed when the mouse is let up and a capture ends.
    FSimpleDelegate OnMouseCaptureEnd;
 
    // Holds a delegate that is executed when a new value is selected on the color spectrum.
    FOnLinearColorValueChanged OnValueChanged;
};