On 01.01.2011 15:25, Juha Manninen wrote:
It is the same as the new Delphi unicode support, I think. All GUI
components support unicode out of the box, it uses UTF8 encoded
strings.
AFAIK Delphi uses UTF16, so in that way it is different.
I must ask a newbie question again. I never needed to pay attention to
this because char encodings in GUIs have worked well for my purposes.
The GUI text properties have type "string" which is ansistring with the
normal H+ setting.
TCaption is defined as "string", too.
Examples: TEdit.Text, TMemo.Lines[0]
What happens when I do:
var s: string;
...
s := TMemo.Lines[0];
Is it converted somehow?
The native widget's encoding is either UTF-8 or UTF-16.
Is the string actually a Utf8String or Utf16String then?
When do I need to pay attention to it?
Currently there is no automatic conversion (it's planned in one of the
branches of FPC). For now a String (=AnsiString) can be seen as an
"array of byte". You as a developer are responsible that the string
contains the correct encoding.
So in your above example the string that is stored in "s" will be UTF8
encoded, because it comes from the GUI. But if that string contains
multibyte characters those characters will appear as single "one byte"
characters if you access the string using [], Pos, Copy, etc.
Example (note: this is not accurate UTF8 encoding, I'm just making that
up here)
TMemo.Lines[0] contains: 'hä?!' ( h a-umlaut ? ! )
I now assume that an a-umlaut is encoded as "ae" (which isn't really the
case, but it's for the sake of an example ^^)
s now contains: 'h a e ? !'
If you now want to access the second character of s you'd expect that
you'd get the a-umlaut, but if you do s[2] you'll get an "a". And if you
access the third one (s[3]) you'll get the "e" instead of "?".
You need to convert the UTF8 string to a different one, e.g. UTF16:
var
us: UnicodeString;
begin
us := UTF8Encode(s);
end;
Now us[2] will return the a-umlaut.
I hope this example clears that up a bit, if not: just ask more questions ;)
Regards,
Sven
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