SColorBlock.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 "Styling/AppStyle.h"
 
class FPaintArgs;
class FSlateWindowElementList;
 
enum class EColorBlockAlphaDisplayMode : uint8
{
    // Draw a single block that draws color and opacity as one. I.E the entire block will be semi-transparent if opacity < 1
    Combined,
    // The color block is split into in half. The left half draws the color with opacity and the right half draws without any opacity
    Separate,
    // The color block is split into in half. The left half draws the color without any opacity and the right half draws with opacity
    SeparateReverse,
    // Alpha is omitted from display
    Ignore,
};
 
 
template <>
struct TWidgetTypeTraits<class SColorBlock>
{
    static constexpr bool SupportsInvalidation() { return true; }
};
 
class SColorBlock : public SLeafWidget
{
    SLATE_DECLARE_WIDGET_API(SColorBlock, SLeafWidget, SLATE_API)
 
public:
 
    SLATE_BEGIN_ARGS(SColorBlock)
        : _Color(FLinearColor::White)
        , _AlphaBackgroundBrush(FAppStyle::Get().GetBrush("ColorPicker.RoundedAlphaBackground"))
        , _CornerRadius(0.0f)
        , _ColorIsHSV(false)
        , _ShowBackgroundForAlpha(false)
        , _UseSRGB(true)
        , _AlphaDisplayMode(EColorBlockAlphaDisplayMode::Combined)
        , _Size(FVector2D(16, 16))
        , _OnMouseButtonDown()
    {}
 
        SLATE_ATTRIBUTE(FLinearColor, Color)
 
        
        SLATE_ATTRIBUTE(const FSlateBrush*, AlphaBackgroundBrush)
 
        
        SLATE_ATTRIBUTE(FVector4, CornerRadius)
 
        
        SLATE_ATTRIBUTE(bool, ColorIsHSV)
 
        
        SLATE_ATTRIBUTE(bool, ShowBackgroundForAlpha)
 
        
        SLATE_ATTRIBUTE(bool, UseSRGB)
 
        
        SLATE_ATTRIBUTE(EColorBlockAlphaDisplayMode, AlphaDisplayMode)
 
        
        SLATE_ATTRIBUTE(FVector2D, Size)
 
        
        SLATE_EVENT(FPointerEventHandler, OnMouseButtonDown)
 
    SLATE_END_ARGS()
 
public:
    SLATE_API SColorBlock();
    SLATE_API ~SColorBlock();
 
    SLATE_API void Construct(const FArguments& InArgs);
 
private:
    // SWidget overrides
    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 FReply OnMouseButtonDown(const FGeometry& MyGeometry, const FPointerEvent& MouseEvent) override;
    SLATE_API virtual FVector2D ComputeDesiredSize(float) const override;
 
    void MakeSection(TArray<FSlateGradientStop>& OutGradientStops, FVector2D StartPt, FVector2D EndPt, FLinearColor Color, const FWidgetStyle& InWidgetStyle, bool bIgnoreAlpha) const;
 
private:
    TSlateAttribute<FLinearColor> Color;
 
    TSlateAttribute<const FSlateBrush*> AlphaBackgroundBrush;
 
    TSlateAttribute<FVector4> GradientCornerRadius;
 
    TSlateAttribute<FVector2D> ColorBlockSize;
 
    FPointerEventHandler MouseButtonDownHandler;
 
    TSlateAttribute<EColorBlockAlphaDisplayMode> AlphaDisplayMode;
 
    TSlateAttribute<bool> ColorIsHSV;
 
    TSlateAttribute<bool> ShowBackgroundForAlpha;
 
    TSlateAttribute<bool> bUseSRGB;
};