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03-UnrealEngine/Gameplay/UObject/UnrealSpecifiers/Meta/String/MultiLine/MultiLine.md

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+# MultiLine
+
+- **功能描述：** 使得文本属性编辑框支持换行。
+- **使用位置：** UPROPERTY
+- **引擎模块：** String/Text Property
+- **元数据类型：** bool
+- **限制类型：** FName/FString/Fext
+- **常用程度：** ★★★★★
+
+使得文本属性编辑框支持换行。换行后的字符串以”\r\n”分隔换行。
+
+## 测试代码：
+
+```cpp
+	UPROPERTY(EditAnywhere, Category = MultiLineTest, meta = (MultiLine = true))
+	FString MyString_MultiLine = TEXT("Hello");
+
+	UPROPERTY(EditAnywhere, Category = MultiLineTest, meta = (MultiLine = true))
+	FText MyText_MultiLine = INVTEXT("Hello");
+
+	UPROPERTY(EditAnywhere, Category = MultiLineTest, meta = (MultiLine = true, PasswordField = true))
+	FString MyString_MultiLine_Password = TEXT("Hello");
+
+	UPROPERTY(EditAnywhere, Category = MultiLineTest, meta = (MultiLine = true, PasswordField = true))
+	FText MyText_MultiLine_Password  = INVTEXT("Hello");
+```
+
+## 测试结果：
+
+按住Shift+Enter回车换行。
+
+![Untitled](Untitled.png)
+
+## 原理：
+
+原理也很简单，根据bIsMultiLine 创建特定的多行编辑控件SMultiLineEditableTextBox。
+
+```cpp
+void SPropertyEditorText::Construct( const FArguments& InArgs, const TSharedRef< class FPropertyEditor >& InPropertyEditor )
+{
+bIsMultiLine = PropertyHandle->GetBoolMetaData(NAME_MultiLine);
+		
+		if(bIsMultiLine)
+		{
+			ChildSlot
+			[
+				SAssignNew(HorizontalBox, SHorizontalBox)
+				+SHorizontalBox::Slot()
+				.FillWidth(1.0f)
+				[
+					SAssignNew(MultiLineWidget, SMultiLineEditableTextBox)
+					.Text(InPropertyEditor, &FPropertyEditor::GetValueAsText)
+					.Font(InArgs._Font)
+					.SelectAllTextWhenFocused(false)
+					.ClearKeyboardFocusOnCommit(false)
+					.OnTextCommitted(this, &SPropertyEditorText::OnTextCommitted)
+					.OnVerifyTextChanged(this, &SPropertyEditorText::OnVerifyTextChanged)
+					.SelectAllTextOnCommit(false)
+					.IsReadOnly(this, &SPropertyEditorText::IsReadOnly)
+					.AutoWrapText(true)
+					.ModiferKeyForNewLine(EModifierKey::Shift)
+					//.IsPassword( bIsPassword )
+				]
+			];
+		
+			PrimaryWidget = MultiLineWidget;
+		}
+	
+}
+```