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03-UnrealEngine/Gameplay/UObject/UnrealSpecifiers/Meta/Object/DisplayThumbnail/DisplayThumbnail.md

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+# DisplayThumbnail
+
+- **功能描述：** 指定是否在该属性左侧显示一个缩略图。
+- **使用位置：** UPROPERTY
+- **引擎模块：** Object Property
+- **元数据类型：** bool
+- **限制类型：** UObject*
+- **关联项：** [ThumbnailSize](../ThumbnailSize.md)
+- **常用程度：** ★★★
+
+指定是否在该属性左侧显示一个缩略图。
+
+## 测试代码：
+
+```cpp
+UCLASS(Blueprintable, BlueprintType)
+class INSIDER_API AMyActor_Thumbnail_Test :public AActor
+{
+	GENERATED_BODY()
+public:
+	UPROPERTY(EditAnywhere, BlueprintReadWrite, meta = (DisplayThumbnail = "false"))
+	UObject* MyObject;
+
+	UPROPERTY(EditAnywhere, BlueprintReadWrite, meta = (DisplayThumbnail = "true"))
+	UObject* MyObject_DisplayThumbnail;
+
+	UPROPERTY(EditAnywhere, BlueprintReadWrite)
+	AActor* MyActor;
+
+	UPROPERTY(EditAnywhere, BlueprintReadWrite, meta = (DisplayThumbnail = "true"))
+	AActor* MyActor_DisplayThumbnail;
+};
+
+```
+
+## 测试效果：
+
+可见MyObject_DisplayThumbnail的左侧显示出了所选择资产的缩略图，而MyObject因为设置了false因此是没有的。如果不设置DisplayThumbnail =false，则默认也是会显示缩略图的。
+
+MyActor_DisplayThumbnail出现了缩略图的图标，但是发现并没有显示出正确的说了图。AActor在默认情况下是不显示缩略图的。
+
+![Untitled](Untitled.png)
+
+## 原理：
+
+判断是否要显示缩略图就在这个函数。
+
+默认情况下非Actor类型才会显示。另外SPropertyEditorAsset是用在资产类型属性上的，其实就是Object属性。
+
+```cpp
+bool SPropertyEditorAsset::ShouldDisplayThumbnail(const FArguments& InArgs, const UClass* InObjectClass) const
+{
+	if (!InArgs._DisplayThumbnail || !InArgs._ThumbnailPool.IsValid())
+	{
+		return false;
+	}
+
+	bool bShowThumbnail = InObjectClass == nullptr || !InObjectClass->IsChildOf(AActor::StaticClass());
+
+	// also check metadata for thumbnail & text display
+	const FProperty* PropertyToCheck = nullptr;
+	if (PropertyEditor.IsValid())
+	{
+		PropertyToCheck = PropertyEditor->GetProperty();
+	}
+	else if (PropertyHandle.IsValid())
+	{
+		PropertyToCheck = PropertyHandle->GetProperty();
+	}
+
+	if (PropertyToCheck != nullptr)
+	{
+		PropertyToCheck = GetActualMetadataProperty(PropertyToCheck);
+
+		return GetTagOrBoolMetadata(PropertyToCheck, TEXT("DisplayThumbnail"), bShowThumbnail);
+	}
+
+	return bShowThumbnail;
+}
+```