78 lines
2.6 KiB
Markdown
78 lines
2.6 KiB
Markdown
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# ValidateWidgetUsing
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- **功能描述：** 提供一个函数来验证当前属性值是否合法。
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- **使用位置：** UPROPERTY
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- **引擎模块：** Scene
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- **元数据类型：** bool
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- **限制类型：** 带有MakeEditWidget的FVector，FTransform
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- **关联项：** [MakeEditWidget](../MakeEditWidget/MakeEditWidget.md)
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- **常用程度：** ★★★
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ValidateWidgetUsing提供一个函数来验证当前属性值是否合法。
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- 当前属性要有MakeEditWidget的标记
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- 函数的原型是FString MyFunc()，返回非空表示错误信息。
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## 测试代码：
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```cpp
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UFUNCTION()
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FString ValidateMyVector()
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{
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if (MyVector_MakeEditWidget_Validate.Length()>100.f)
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{
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return TEXT("Exceed max length:100");
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}
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return TEXT("");
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}
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UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = "EditWidget", meta = (MakeEditWidget, ValidateWidgetUsing = "ValidateMyVector"))
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FVector MyVector_MakeEditWidget_Validate;
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```
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## 测试结果：
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可见MyVector_MakeEditWidget_Validate长度超过100之后，控件颜色变成红色，并且显示出错误的信息在控件上。
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## 原理：
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逻辑比较简单。发现有验证函数，就调用验证函数来验证。如果有错误信息，就一起改变最终输出的颜色和显示文字。
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```cpp
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static FLegacyEdModeWidgetHelper::FPropertyWidgetInfo CreateWidgetInfo(const TArray<FPropertyWidgetInfoChainElement>& Chain, bool bIsTransform, FProperty* CurrentProp, int32 Index = INDEX_NONE)
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{
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check(CurrentProp);
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FEdMode::FPropertyWidgetInfo WidgetInfo;
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WidgetInfo.PropertyValidationName = FName(*CurrentProp->GetMetaData(FEdMode::MD_ValidateWidgetUsing));
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return WidgetInfo;
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}
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void FLegacyEdModeWidgetHelper::FPropertyWidgetInfo::GetTransformAndColor(UObject* BestSelectedItem, bool bIsSelected, FTransform& OutLocalTransform, FString& OutValidationMessage, FColor& OutDrawColor) const
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{
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// Determine the desired color
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if (PropertyValidationName != NAME_None)
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{
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if (UFunction* ValidateFunc = BestSelectedItem->FindFunction(PropertyValidationName))
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{
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BestSelectedItem->ProcessEvent(ValidateFunc, &OutValidationMessage);
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// if we have a negative result, the widget color is red.
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OutDrawColor = OutValidationMessage.IsEmpty() ? OutDrawColor : FColor::Red;
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}
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}
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}
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void FLegacyEdModeWidgetHelper::DrawHUD(FEditorViewportClient* ViewportClient, FViewport* Viewport, const FSceneView* View, FCanvas* Canvas)
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{
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FTransform LocalWidgetTransform;
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FString ValidationMessage;
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FColor WidgetColor;
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WidgetInfo.GetTransformAndColor(BestSelectedItem, bSelected, /*out*/ LocalWidgetTransform, /*out*/ ValidationMessage, /*out*/ WidgetColor);
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Canvas->DrawItem(TextItem);
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}
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```
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