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Eliminates exceptions when characters are outside ISO-8859-1 range #672

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Merged
Shane32 merged 2 commits into from
Oct 13, 2025
Merged

Eliminates exceptions when characters are outside ISO-8859-1 range #672

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0c9a563
Eliminates exceptions when characters are outside ISO-8859-1 range
Shane32 Oct 13, 2025
f50cc48
fix comment
Shane32 Oct 13, 2025
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17 changes: 8 additions & 9 deletions QRCoder/QRCodeGenerator.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -995,22 +995,21 @@ private static int GetDataLength(EncodingMode encoding, string plainText, BitArr
bool IsUtf8() => (encoding == EncodingMode.Byte && (forceUtf8 || !IsValidISO(plainText)));
}

private static readonly Encoding _iso88591ExceptionFallback = Encoding.GetEncoding(28591, new EncoderExceptionFallback(), new DecoderExceptionFallback()); // ISO-8859-1
/// <summary>
/// Checks if the given string can be accurately represented and retrieved in ISO-8859-1 encoding.
/// </summary>
private static bool IsValidISO(string input)
{
// No heap allocations if the string is ISO-8859-1
try
// ISO-8859-1 contains the same characters as UTF-16 for the range 0x00-0xFF.
// 0x00-0x7F: ASCII (0-127)
// 0x80-0x9F: C1 control characters (128-159)
// 0xA0-0xFF: Extended Latin (160-255)
foreach (char c in input)
{
_ = _iso88591ExceptionFallback.GetByteCount(input);
return true;
}
catch (EncoderFallbackException) // The exception is a heap allocation and not ideal
{
return false;
if (c > 0xFF)
return false;
}
return true;
}

/// <summary>
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