UE5 Slate中的StreeView的基础创建方法

.h
// Fill out your copyright notice in the Description page of Project Settings.
 
#pragma once
 
#include "CoreMinimal.h"
#include "Widgets/SCompoundWidget.h"
 
/**
 * 
 */
class MYALONESLATE_API SMyTreeView : public SCompoundWidget
{
public:
	SLATE_BEGIN_ARGS(SMyTreeView)
		{
		}
 
	SLATE_ARGUMENT(FText,buttontext)
 
	SLATE_END_ARGS()
 
	/** Constructs this widget with InArgs */
	void Construct(const FArguments& InArgs);
 
	TSharedRef OnGenerateRowForList(TSharedPtr Item, const TSharedRef& OwnerTable);
	void OnGetChildrenForTree(TSharedPtr Item, TArray>& OutChildren);
 
private:
	TArray> Items;
	
	TMap>> ChildrenMap;
};

.cpp
 
// Fill out your copyright notice in the Description page of Project Settings.
 
 
#include "MyTreeView.h"
 
#include "SlateOptMacros.h"
 
BEGIN_SLATE_FUNCTION_BUILD_OPTIMIZATION
 
void SMyTreeView::Construct(const FArguments& InArgs)
{
	// 初始化根节点
	Items.Add(MakeShared("thisA"));
	Items.Add(MakeShared("thisB"));
	Items.Add(MakeShared("thisC"));
 
	// 初始化子节点
	ChildrenMap.Add("thisA", TArray>{ MakeShared("thisAaaa") });
	ChildrenMap.Add("thisB", TArray>{ MakeShared("thisBaaa"), MakeShared("thisBbbb") });
	ChildrenMap.Add("thisC", TArray>{ MakeShared("thisCaaa") });
 
	ChildSlot
	[
		SNew(STreeView>)
		.TreeItemsSource(&Items) // Items是一个包含TSharedPtr的数组
		.OnGenerateRow(this, &SMyTreeView::OnGenerateRowForList)
		.OnGetChildren(this, &SMyTreeView::OnGetChildrenForTree)
	];
}
 
TSharedRef SMyTreeView::OnGenerateRowForList(TSharedPtr Item,
	const TSharedRef& OwnerTable)
{
	return SNew(STableRow>, OwnerTable)
   [
	   SNew(STextBlock)
	   .Text(FText::FromString(*Item))
	   .Font(FSlateFontInfo(FPaths::EngineContentDir() / TEXT("Slate/Fonts/Roboto-Regular.ttf"), 24)) // 设置字体大小为24
   ];
}
 
void SMyTreeView::OnGetChildrenForTree(TSharedPtr Item, TArray>& OutChildren)
{
	const TArray>* FoundChildren = ChildrenMap.Find(*Item);
	if (FoundChildren)
	{
		OutChildren = *FoundChildren;
	}
}
 
 
 
 
END_SLATE_FUNCTION_BUILD_OPTIMIZATION

STableRow的GetExpanderIndentPadding函数控制根节点前的默认图标，要修改需要创建一个继承至STableRow的类，通过重写GetExpanderWidget函数来改变展开和折叠的图标。需要将"ClassIcon.Plus"和"ClassIcon.Minus"替换为自己的样式。

class SMyTableRow : public STableRow>
{
public:
    SLATE_BEGIN_ARGS(SMyTableRow) {}
    SLATE_END_ARGS()
 
    void Construct(const FArguments& InArgs, const TSharedRef& InOwnerTableView)
    {
        STableRow::Construct(
            STableRow::FArguments()
            .Style(FCoreStyle::Get(), "NoBorder")
            .ShowSelection(false),
            InOwnerTableView);
    }
 
    virtual TSharedRef GenerateWidgetForColumn(const FName& ColumnName) override
    {
        return SNew(STextBlock).Text(FText::FromString(*Item));
    }
 
    virtual TSharedRef GetExpanderWidget() override
    {
        return SNew(SImage)
        .Image(this, &SMyTableRow::GetExpanderImage);
    }
 
    const FSlateBrush* GetExpanderImage() const
    {
        static FSlateBrush PlusImage = FSlateIconFinder::FindIconBrushForClass("ClassIcon.Plus");
        static FSlateBrush MinusImage = FSlateIconFinder::FindIconBrushForClass("ClassIcon.Minus");
 
        return IsItemExpanded() ? &MinusImage : &PlusImage;
    }
};

然后在OnGenerateRowForList函数中使用SMyTableRow来替换STableRow：

TSharedRef<ITableRow> SMyTreeView::OnGenerateRowForList(TSharedPtr<FString> Item, const TSharedRef<STableViewBase>& OwnerTable)
{
    return SNew(SMyTableRow, OwnerTable)
    .Item(Item);
}