95 lines
3.1 KiB
Markdown
95 lines
3.1 KiB
Markdown
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# AllowedCharacters
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- **功能描述：** 只允许文本框里可以输入这些字符。
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- **使用位置：** UPROPERTY
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- **引擎模块：** String/Text Property
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- **元数据类型：** string="abc"
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- **限制类型：** FName/FString/Fext
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- **常用程度：** ★★★
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只允许文本框里可以输入这些字符。
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## 测试代码：
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```cpp
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public:
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UPROPERTY(EditAnywhere, Category = AllowedCharactersTest, meta = (AllowedCharacters = "abcde"))
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FString MyString_AllowedCharacters;
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UPROPERTY(EditAnywhere, Category = AllowedCharactersTest, meta = (AllowedCharacters = "你好"))
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FString MyString_AllowedCharacters_Chinese;
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```
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## 测试效果：
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可见第一个只能输入abcde，而fgh产生了报错。在测试中文的时候，如果粘贴进去对应的中文，则是OK的。否则也会产生报错，不允许输入进去。
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## 原理：
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SPropertyEditorText里实际保存了FCharRangeList 的AllowedCharacters用来限制字符。同样在字符串改变的时候，验证字符是否合法。
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```cpp
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FCharRangeList AllowedCharacters;
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AllowedCharacters.InitializeFromString(PropertyHandle->GetMetaData(NAME_AllowedCharacters));
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bool SPropertyEditorText::OnVerifyTextChanged(const FText& Text, FText& OutError)
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{
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const FString& TextString = Text.ToString();
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if (MaxLength > 0 && TextString.Len() > MaxLength)
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{
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OutError = FText::Format(LOCTEXT("PropertyTextTooLongError", "This value is too long ({0}/{1} characters)"), TextString.Len(), MaxLength);
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return false;
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}
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if (!AllowedCharacters.IsEmpty())
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{
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if (!TextString.IsEmpty() && !AllowedCharacters.AreAllCharsIncluded(TextString))
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{
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TSet<TCHAR> InvalidCharacters = AllowedCharacters.FindCharsNotIncluded(TextString);
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FString InvalidCharactersString;
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for (TCHAR Char : InvalidCharacters)
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{
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if (!InvalidCharactersString.IsEmpty())
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{
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InvalidCharactersString.AppendChar(TEXT(' '));
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}
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InvalidCharactersString.AppendChar(Char);
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}
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OutError = FText::Format(LOCTEXT("PropertyTextCharactersNotAllowedError", "The value may not contain the following characters: {0}"), FText::FromString(InvalidCharactersString));
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return false;
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}
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}
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if (PropertyValidatorFunc.IsBound())
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{
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FText Result = PropertyValidatorFunc.Execute(TextString);
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if (!Result.IsEmpty())
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{
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OutError = Result;
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return false;
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}
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}
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return true;
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}
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```
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根据FCharRangeList的定义，限制字符的格式是：
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```cpp
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/** Initializes this instance with the character ranges represented by the passed definition string.
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* A definition string contains characters and ranges of characters, one after another with no special separators between them.
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* Characters - and \ must be escaped like this: \- and \\
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*
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* Examples:
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* "aT._" <-- Letters 'a' and 'T', dot and underscore.
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* "a-zT._" <-- All letters from 'a' to 'z', letter 'T', dot and underscore.
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* "a-zA-Z0-9._" <-- All lowercase and uppercase letters, all digits, dot and underscore.
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* "a-zA-Z0-9\-\\._" <-- All lowercase and uppercase letters, all digits, minus sign, backslash, dot and underscore.
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*/
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```
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