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2024-10-12 17:19:46 +08:00
# AllowPreserveRatio
- **功能描述:** 在细节面板上为FVector属性添加一个比率锁。
- **使用位置:** UPROPERTY
- **引擎模块:** Numeric Property
- **元数据类型:** bool
- **限制类型:** FVector
- **常用程度:** ★★★
在细节面板上为FVector属性添加一个比率锁。
## 测试代码:
```cpp
public:
UPROPERTY(EditAnywhere, Category = VectorTest)
FVector MyVector_Default;
UPROPERTY(EditAnywhere, Category = VectorTest, meta = (AllowPreserveRatio))
FVector MyVector_AllowPreserveRatio;
UPROPERTY(EditAnywhere, Category = VectorTest, meta = (ShowNormalize))
FVector MyVector_ShowNormalize;
```
## 测试结果:
可见MyVector_AllowPreserveRatio的值在锁上之后可以形成固定的比率。
![AllowPreserveRatio](AllowPreserveRatio.gif)
## 原理:
其实就是UI定制化的时候检测出AllowPreserveRatio就创建单独的UI。
```cpp
void FMathStructCustomization::MakeHeaderRow(TSharedRef<class IPropertyHandle>& StructPropertyHandle, FDetailWidgetRow& Row)
{
if (StructPropertyHandle->HasMetaData("AllowPreserveRatio"))
{
if (!GConfig->GetBool(TEXT("SelectionDetails"), *(StructPropertyHandle->GetProperty()->GetName() + TEXT("_PreserveScaleRatio")), bPreserveScaleRatio, GEditorPerProjectIni))
{
bPreserveScaleRatio = true;
}
HorizontalBox->AddSlot()
.AutoWidth()
.MaxWidth(18.0f)
.VAlign(VAlign_Center)
[
// Add a checkbox to toggle between preserving the ratio of x,y,z components of scale when a value is entered
SNew(SCheckBox)
.IsChecked(this, &FMathStructCustomization::IsPreserveScaleRatioChecked)
.OnCheckStateChanged(this, &FMathStructCustomization::OnPreserveScaleRatioToggled, StructWeakHandlePtr)
.Style(FAppStyle::Get(), "TransparentCheckBox")
.ToolTipText(LOCTEXT("PreserveScaleToolTip", "When locked, scales uniformly based on the current xyz scale values so the object maintains its shape in each direction when scaled"))
[
SNew(SImage)
.Image(this, &FMathStructCustomization::GetPreserveScaleRatioImage)
.ColorAndOpacity(FSlateColor::UseForeground())
]
];
}
}
```