PaginateScrollWidget.h

// Copyright 2022 Stream.IO, Inc. All Rights Reserved.
 
#pragma once
 
#include "Components/ScrollBox.h"
#include "CoreMinimal.h"
#include "StreamWidget.h"
 
#include "PaginateScrollWidget.generated.h"
 
UCLASS()
class STREAMCHATUI_API UPaginateScrollWidget : public UStreamWidget
{
    GENERATED_BODY()
 
public:
    UPROPERTY(EditAnywhere, Category = Pagination)
    int32 Limit = 20;
 
    DECLARE_DYNAMIC_MULTICAST_DELEGATE_TwoParams(FPaginatingMessagesDelegate, EPaginationDirection, Direction, EHttpRequestState, RequestState);
    UPROPERTY(BlueprintAssignable)
    FPaginatingMessagesDelegate OnPaginatingMessages;
 
protected:
    virtual void NativeConstruct() override;
    virtual void NativeDestruct() override;
 
    virtual void SetChildren(const TArray<UWidget*>&);
 
    virtual void Paginate(EPaginationDirection Directions, TFunction<void()> Callback)
    {
    }
 
    UPROPERTY(meta = (BindWidget))
    UScrollBox* ScrollBox;
 
    // If the scroll offset is below this value, then new messages will be fetched
    UPROPERTY(EditDefaultsOnly, Category = Defaults)
    float PaginateScrollThreshold = 100.f;
 
    // The end of the scroll box which causes pagination to be triggered
    UPROPERTY(EditDefaultsOnly, Category = Defaults)
    EPaginationDirection PaginationDirection = EPaginationDirection::Bottom;
 
private:
    UFUNCTION()
    void OnUserScroll(float CurrentOffset);
    void SetPaginationRequestState(EHttpRequestState, EPaginationDirection);
    EPaginationDirection GetDirections() const;
 
    EPaginationDirection EndedPaginationDirections = EPaginationDirection::None;
    EHttpRequestState PaginationRequestState = EHttpRequestState::Ended;
};