More than two bytes wide Unicode characters are broken

answered 2014-06-18 14:34:01 +0200

jbrooks
2162 ●22 ●22 ●22

moderator

There is quite a bit of confusion here, so I'm going to start a separate answer to try to clarify it.

First of all, UTF16 (and by extension, QString, QChar, and Qt as a whole) can encode the entire unicode character set, including the characters that can't be represented in 16 bits. Surrogate pairs are supported, and the characters do render correctly in Qt applications. They are often ignored in text parsing and that can result in some issues, but it's generally trivial.

So, breaking down the specific problems here:

• Virtual keyboard (Popper.qml) not handling surrogate pairs

None of the built-in keyboards have characters outside the BMP that would require more than one QChar to encode. The keyboard QML is not considered a real API at present. Unfortunately, I don't think we can accept community patches to it yet.

• Android text input

I'm not sure what you mean by this.

• SMS sending

Our modem is failing to encode unicode surrogate pairs in outgoing SMS properly. I will file a bug and look into this.

• Variant selector

I am not very familiar with unicode variant selectors. Can you please try a simple QML example rendering a unicode character with a variant selector using a specific font, and either:

1) Demonstrate that the same font renders the same character correctly using other non-Qt text engines, or 2) Demonstrate that the same QML with the same font works on desktop Qt but not on Sailfish

My guess is that this is a feature missing in Qt's text rendering. If you can make a test case for that, we can report it upstream.

I hope this helps.