SNumericDropDown.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "CoreMinimal.h"
#include "Misc/Attribute.h"
#include "Layout/Visibility.h"
#include "Input/Events.h"
#include "Widgets/SWidget.h"
#include "Textures/SlateIcon.h"
#include "Layout/Margin.h"
#include "Widgets/DeclarativeSyntaxSupport.h"
#include "Widgets/SCompoundWidget.h"
#include "Widgets/SBoxPanel.h"
#include "Framework/Commands/UIAction.h"
#include "Framework/MultiBox/MultiBoxBuilder.h"
#include "Widgets/Text/STextBlock.h"
#include "Framework/Application/SlateApplication.h"
#include "Widgets/Input/SEditableTextBox.h"
#include "Widgets/Input/SComboButton.h"
 
template<typename NumericType>
class SNumericDropDown : public SCompoundWidget
{
public:
    DECLARE_DELEGATE_OneParam( FOnValueChanged, NumericType );
 
public:
    class FNamedValue
    {
    public:
        FNamedValue( NumericType InValue, FText InName, FText InDescription )
        {
            Value = InValue;
            Name = InName;
            Description = InDescription;
        }
 
        NumericType GetValue() const
        {
            return Value;
        }
 
        FText GetName() const
        {
            return Name;
        }
 
        FText GetDescription() const
        {
            return Description;
        }
 
    private:
        NumericType Value;
        FText Name;
        FText Description;
    };
 
public:
    SLATE_BEGIN_ARGS( SNumericDropDown<NumericType> )
        : _DropDownValues()
        , _LabelText()
        , _Orientation( EOrientation::Orient_Horizontal )
        , _MinDesiredValueWidth( 40 )
        , _bShowNamedValue(false)
        {}
 
        SLATE_ARGUMENT( TArray<FNamedValue>, DropDownValues )
        SLATE_ATTRIBUTE( FText, LabelText )
        SLATE_ATTRIBUTE( EOrientation, Orientation )
        SLATE_ATTRIBUTE( float, MinDesiredValueWidth )
        SLATE_ATTRIBUTE( bool, bShowNamedValue )
        SLATE_ATTRIBUTE( NumericType, Value )
        SLATE_EVENT( FOnValueChanged, OnValueChanged )
 
    SLATE_END_ARGS()
 
    void Construct( const FArguments& InArgs )
    {
        DropDownValues = InArgs._DropDownValues;
        LabelText = InArgs._LabelText;
        Orientation = InArgs._Orientation;
        bShowNamedValue = InArgs._bShowNamedValue;
        Value = InArgs._Value;
        OnValueChanged = InArgs._OnValueChanged;
 
        ChildSlot
        [
            SNew( SVerticalBox )
            // Vertical Label
            + SVerticalBox::Slot()
            .AutoHeight()
            .Padding( FMargin( 0, 0, 0, 3 ) )
            [
                SNew( STextBlock )
                .Text(LabelText)
                .Visibility(this, &SNumericDropDown<NumericType>::GetLabelVisibility, EOrientation::Orient_Vertical)
            ]
            + SVerticalBox::Slot()
            .AutoHeight()
            [
                SNew( SHorizontalBox )
                // Horizontal Icon Label
                + SHorizontalBox::Slot()
                .VAlign( EVerticalAlignment::VAlign_Center )
                .AutoWidth()
                .Padding( FMargin( 0, 0, 3, 0 ) )
                [
                    
                    SNew( STextBlock )
                    .Text(LabelText)
                    .Visibility( this, &SNumericDropDown<NumericType>::GetLabelVisibility, EOrientation::Orient_Horizontal )
                ]
                + SHorizontalBox::Slot()
                [
                    SNew( SComboButton )
                    .ContentPadding( 1 )
                    .OnGetMenuContent( this, &SNumericDropDown<NumericType>::BuildMenu )
                    .ButtonContent()
                    [
                        SNew( SEditableTextBox )
                        .MinDesiredWidth( InArgs._MinDesiredValueWidth )
                        .RevertTextOnEscape(true)
                        .SelectAllTextWhenFocused(true)
                        .Text( this, &SNumericDropDown<NumericType>::GetValueText )
                        .OnTextCommitted( this, &SNumericDropDown<NumericType>::ValueTextComitted )
                    ]
                ]
            ]
        ];
    }
 
private:
    EVisibility GetLabelVisibility( EOrientation LabelOrientation ) const
    {
        return Orientation.Get() == LabelOrientation
            ? EVisibility::Visible
            : EVisibility::Collapsed;
    }
 
    FText GetValueText() const
    {
        if (bShowNamedValue.Get())
        {
            for ( FNamedValue DropDownValue : DropDownValues )
            {
                if (FMath::IsNearlyEqual(DropDownValue.GetValue(), Value.Get()))
                {
                    return DropDownValue.GetName();
                }
            }
        }
        return FText::AsNumber( Value.Get() );
    }
 
    void ValueTextComitted( const FText& InNewText, ETextCommit::Type InTextCommit )
    {
        if ( InNewText.IsNumeric() )
        {
            NumericType NewValue;
            TTypeFromString<NumericType>::FromString( NewValue, *InNewText.ToString() );
            OnValueChanged.ExecuteIfBound(NewValue);
        }
    }
 
    TSharedRef<SWidget> BuildMenu()
    {
        FMenuBuilder MenuBuilder( true, NULL );
 
        for ( FNamedValue DropDownValue : DropDownValues )
        {
            FUIAction MenuAction(FExecuteAction::CreateSP(this, &SNumericDropDown::SetValue, DropDownValue.GetValue()));
            MenuBuilder.AddMenuEntry(DropDownValue.GetName(), DropDownValue.GetDescription(), FSlateIcon(), MenuAction);
        }
 
        return MenuBuilder.MakeWidget();
    }
 
    void SetValue( NumericType InValue )
    {
        FSlateApplication::Get().ClearKeyboardFocus( EFocusCause::Cleared );
        OnValueChanged.ExecuteIfBound(InValue);
    }
 
private:
    TArray<FNamedValue> DropDownValues;
    TAttribute<FText> LabelText;
    TAttribute<EOrientation> Orientation;
    TAttribute<bool> bShowNamedValue;
    TAttribute<NumericType> Value;
    FOnValueChanged OnValueChanged;
};