72 lines
4.0 KiB
Markdown
72 lines
4.0 KiB
Markdown
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# CtrlMultiplier
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- **功能描述：** 指定数字输入框在Ctrl按下时鼠标轮滚动和鼠标拖动改变值的倍率。
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- **使用位置：** UPROPERTY
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- **引擎模块：** Numeric Property
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- **元数据类型：** float/int
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- **限制类型：** 数据结构：FVector，FRotator，FColor
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- **关联项：** [ShiftMultiplier](../ShiftMultiplier.md)
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- **常用程度：** ★★
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指定数字输入框在Ctrl按下时鼠标轮滚动和鼠标拖动改变值的倍率。
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- CtrlMultiplier的默认值是0.1f，一般作为一种精调模式。
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- 直接设置到float属性上并无效果。默认情况下，属性上的CtrlMultiplier并不会设置到SNumericEntryBox和SSpinBox上，因为这二者并不会直接从property上提取meta来设置到其本身的Multiplier值上。
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- 在源码里发现FMathStructCustomization里会提取CtrlMultiplier和ShiftMultiplier的值，因此我们可以在一些数学结构上设置，如FVector，FRotator，FColor
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- 如果自己定义Customization和创建SSpinBox，则可以自己提取Multiplier的值自己设置到控件里去。
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## 测试代码：
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```cpp
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UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = MultiplierTest, meta = (CtrlMultiplier = "5"))
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float MyFloat_HasCtrlMultiplier = 100;
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UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = MultiplierTest, meta = (ShiftMultiplier = "100"))
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float MyFloat_HasShiftMultiplier = 100;
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UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = MultiplierTest)
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FVector MyVector_NoMultiplier;
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UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = MultiplierTest, meta = (CtrlMultiplier = "5"))
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FVector MyVector_HasCtrlMultiplier;
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UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = MultiplierTest, meta = (ShiftMultiplier = "100"))
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FVector MyVector_HasShiftMultiplier;
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```
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## 测试效果：
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- 发现普通float属性测试并无效果，按下Ctrl和Shift依然是默认的改变值0.1和10.f
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- 普通的默认FVector，按下Ctrl和Shift也是默认的改变值0.1和10.f
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- MyVector_HasCtrlMultiplier，发现按下Ctrl，一下子改变幅度是5
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- MyVector_HasShiftMultiplier，发现按下Shift，一下子改变幅度是100
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- 当然用鼠标拖动也是一样的效果，只是那样改变太过剧烈，演示效果不明显
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## 原理：
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```cpp
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SNumericEntryBox的构造函数里：
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, _ShiftMultiplier(10.f)
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, _CtrlMultiplier(0.1f)
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void FMathStructCustomization::MakeHeaderRow(TSharedRef<class IPropertyHandle>& StructPropertyHandle, FDetailWidgetRow& Row)
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{
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for (int32 ChildIndex = 0; ChildIndex < SortedChildHandles.Num(); ++ChildIndex)
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{
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TSharedRef<IPropertyHandle> ChildHandle = SortedChildHandles[ChildIndex];
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// Propagate metadata to child properties so that it's reflected in the nested, individual spin boxes
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ChildHandle->SetInstanceMetaData(TEXT("UIMin"), StructPropertyHandle->GetMetaData(TEXT("UIMin")));
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ChildHandle->SetInstanceMetaData(TEXT("UIMax"), StructPropertyHandle->GetMetaData(TEXT("UIMax")));
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ChildHandle->SetInstanceMetaData(TEXT("SliderExponent"), StructPropertyHandle->GetMetaData(TEXT("SliderExponent")));
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ChildHandle->SetInstanceMetaData(TEXT("Delta"), StructPropertyHandle->GetMetaData(TEXT("Delta")));
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ChildHandle->SetInstanceMetaData(TEXT("LinearDeltaSensitivity"), StructPropertyHandle->GetMetaData(TEXT("LinearDeltaSensitivity")));
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ChildHandle->SetInstanceMetaData(TEXT("ShiftMultiplier"), StructPropertyHandle->GetMetaData(TEXT("ShiftMultiplier")));
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ChildHandle->SetInstanceMetaData(TEXT("CtrlMultiplier"), StructPropertyHandle->GetMetaData(TEXT("CtrlMultiplier")));
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ChildHandle->SetInstanceMetaData(TEXT("SupportDynamicSliderMaxValue"), StructPropertyHandle->GetMetaData(TEXT("SupportDynamicSliderMaxValue")));
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ChildHandle->SetInstanceMetaData(TEXT("SupportDynamicSliderMinValue"), StructPropertyHandle->GetMetaData(TEXT("SupportDynamicSliderMinValue")));
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ChildHandle->SetInstanceMetaData(TEXT("ClampMin"), StructPropertyHandle->GetMetaData(TEXT("ClampMin")));
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ChildHandle->SetInstanceMetaData(TEXT("ClampMax"), StructPropertyHandle->GetMetaData(TEXT("ClampMax")));
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}
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}
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```
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