Difference between revisions of "LCL Unicode Support"

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{{LCL Unicode Support}}
#REDIRECT [[Unicode Support in Lazarus]]
== Introduction ==
As of 0.9.25, Lazarus has full Unicode support in all platforms except Gtk 1. In this page one can find instructions for Lazarus users, roadmaps, descriptions of basic concepts and implementation details.
== Instructions for users ==
Even though Lazarus has Unicode widgetsets, it's important to note that not everything is Unicode. It's the responsibility of the developer to know what is the encoding of their strings and do the proper conversion between libraries which expect different encodings.
Usually the encoding is per-library (e.g. a dynamic library dll or a lazarus package). Each library will uniformly expect 1 kind of encoding, which will usually either be unicode (UTF-8 for Lazarus) or ANSI (which means the system encoding, and may be UTF-8 or not). The RTL and the FCL of FPC 2.4 expect ansi strings. FPC 2.5.x currently too.
You can convert between unicode and ansi using the '''UTF8ToAnsi''' and '''AnsiToUTF8''' functions from the System unit or the '''UTF8ToSys''' and '''SysToUTF8''' from the FileUtil unit. The later two are smarter but pull more code into your program.
===FPC is not Unicode aware===
The Free Pascal Runtime Library (RTL), and the Free Pascal Free Component Library (FCL) in current FPC versions (up to 2.5.x) are ANSI, so you will need to convert strings coming from Unicode libraries or going to Unicode libraries (e.g. the LCL).
===Converting between ANSI and Unicode: examples===
Say you get a string from a TEdit and you want to give it to some rtl file routine:
  MyString: string; // utf-8 encoded
  MyString := MyTEdit.Text;
And for the opposite direction:
  MyString: string; // ansi encoded
  MyString := SomeRTLRoutine;
  MyTEdit.Text := AnsiToUTF8(MyString);
'''Important''': UTF8ToAnsi will return an empty string if the UTF8 string contains invalid characters.
'''Important''': AnsiToUTF8 and UTF8ToAnsi require a widestring manager under Linux, BSD and Mac OS X. You can use the SysToUTF8 and UTF8ToSys functions (unit FileUtil) or add the widestring manager by adding cwstring as one of the first units to your program's uses section.
===Dealing with UTF8 strings and characters===
Until Lazarus 0.9.30 the UTF-8 handling routines were in the LCL in the unit LCLProc. In Lazarus 0.9.31+ the routines in LCLProc are still available for backwards compatibility but the real code to deal with UTF-8 is located in the lazutils package in the unit lazutf8.
To execute operations over UTF-8 strings one should prefer to use routines from the unit lazutf8 instead of routines from the SysUtils routine from Free Pascal, because SysUtils is not yet prepared to deal with Unicode, while lazutf8 is. Simply substitute the routines from SysUtils with their lazutf8 equivalent, which always has the same name except for an added "UTF8" prefix.
Also note that simply iterating over chars as if the string was an array does not work in Unicode. This is not something specific to UTF-8 and one simply cannot suppose that a character will have a fixed size in Unicode. If you want to iterate over the characters of an UTF-8 string, there are basically two ways:
*iterate over the bytes - useful for searching a substring or when looking only at the ASCII characters of the UTF8 string. For example when parsing xml files.
*iterate over the characters - useful for graphical components like synedit. For example when you want to know the third printed character on the screen.
====Searching a substring====
Due to the special nature of UTF8 you can simply use the normal string functions:
<Delphi>uses lazutf8; // LCLProc for Lazarus 0.9.30 or inferior
procedure Where(SearchFor, aText: string);
  BytePos: LongInt;
  CharacterPos: LongInt;
  writeln('The substring "',SearchFor,'" is in the text "',aText,'"',
    ' at byte position ',BytePos,' and at character position ',CharacterPos);
====Accessing UTF8 characters====
Unicode characters can vary in length, so the best solution for accessing them is to use an iteration when one intends to access the characters in the sequence in which they are. For iterating through the characters use this code:
<Delphi>uses lazutf8; // LCLProc for Lazarus 0.9.30 or inferior
procedure DoSomethingWithString(AnUTF8String: string);
  p: PChar;
  CharLen: integer;
  FirstByte, SecondByte, ThirdByte: Char;
    CharLen := UTF8CharacterLength(p);
    // here you have a pointer to the char and it's length
    // You can access the bytes of the UTF-8 Char like this:
    if CharLen >= 1 then FirstByte := P[0];
    if CharLen >= 2 then SecondByte := P[1];
    if CharLen >= 3 then ThirdByte := P[2];
  until (CharLen=0) or (p^ = #0);
====Accessing the Nth UTF8 character====
Besides iterating one might also want to execute a random access to UTF-8 Characters.
<Delphi>uses lazutf8; // LCLProc for Lazarus 0.9.30 or inferior
  AnUTF8String, NthChar: string;
  NthChar := UTF8Copy(AnUTF8String, N, 1);
====Iterating over codepoints using UTF8CharacterToUnicode====
The following demonstrates how to iterate the 32bit code point value of each character in an UTF8 string:
<Delphi>uses lazutf8; // LCLProc for Lazarus 0.9.30 or inferior
procedure IterateUTF8Characters(const AnUTF8String: string);
  p: PChar;
  unicode: Cardinal;
  CharLen: integer;
  until (CharLen=0) or (unicode=0);
====UTF-8 String Copy, Length, LowerCase, etc====
Nearly all operations which one might want to execute with UTF-8 strings are covered by the routines in the unit lazutf8 (unit LCLProc for Lazarus 0.9.30 or inferior). See the following list of routines take from lazutf8.pas:
function UTF8CharacterLength(p: PChar): integer;
function UTF8Length(const s: string): PtrInt;
function UTF8Length(p: PChar; ByteCount: PtrInt): PtrInt;
function UTF8CharacterToUnicode(p: PChar; out CharLen: integer): Cardinal;
function UnicodeToUTF8(u: cardinal; Buf: PChar): integer; inline;
function UnicodeToUTF8SkipErrors(u: cardinal; Buf: PChar): integer;
function UnicodeToUTF8(u: cardinal): shortstring; inline;
function UTF8ToDoubleByteString(const s: string): string;
function UTF8ToDoubleByte(UTF8Str: PChar; Len: PtrInt; DBStr: PByte): PtrInt;
function UTF8FindNearestCharStart(UTF8Str: PChar; Len: integer;
                                  BytePos: integer): integer;
// find the n-th UTF8 character, ignoring BIDI
function UTF8CharStart(UTF8Str: PChar; Len, CharIndex: PtrInt): PChar;
// find the byte index of the n-th UTF8 character, ignoring BIDI (byte len of substr)
function UTF8CharToByteIndex(UTF8Str: PChar; Len, CharIndex: PtrInt): PtrInt;
procedure UTF8FixBroken(P: PChar);
function UTF8CharacterStrictLength(P: PChar): integer;
function UTF8CStringToUTF8String(SourceStart: PChar; SourceLen: PtrInt) : string;
function UTF8Pos(const SearchForText, SearchInText: string): PtrInt;
function UTF8Copy(const s: string; StartCharIndex, CharCount: PtrInt): string;
procedure UTF8Delete(var s: String; StartCharIndex, CharCount: PtrInt);
procedure UTF8Insert(const source: String; var s: string; StartCharIndex: PtrInt);
function UTF8LowerCase(const AInStr: string; ALanguage: string=''): string;
function UTF8UpperCase(const AInStr: string; ALanguage: string=''): string;
function FindInvalidUTF8Character(p: PChar; Count: PtrInt;
                                  StopOnNonASCII: Boolean = false): PtrInt;
function ValidUTF8String(const s: String): String;
procedure AssignUTF8ListToAnsi(UTF8List, AnsiList: TStrings);
//compare functions
function UTF8CompareStr(const S1, S2: string): Integer;
function UTF8CompareText(const S1, S2: string): Integer;
===Dealing with directory and filenames===
Lazarus controls and functions expect filenames and directory names in utf-8 encoding, but the RTL uses ansi strings for directories and filenames.
For example, consider a button, which sets the Directory property of the TFileListBox to the current directory. The RTL Function [[doc:rtl/sysutils/getcurrentdir.html|GetCurrentDir]] is ansi, and not unicode, so conversion is needed:
<delphi>procedure TForm1.Button1Click(Sender: TObject);
  // or use the functions from the FileUtil unit
The unit FileUtil defines common file functions with UTF-8 strings:
<Delphi>// basic functions similar to the RTL but working with UTF-8 instead of the
// system encoding
// AnsiToUTF8 and UTF8ToAnsi need a widestring manager under Linux, BSD, Mac OS X
// but normally these OS use UTF-8 as system encoding so the widestringmanager
// is not needed.
function NeedRTLAnsi: boolean;// true if system encoding is not UTF-8
procedure SetNeedRTLAnsi(NewValue: boolean);
function UTF8ToSys(const s: string): string;// as UTF8ToAnsi but more independent of widestringmanager
function SysToUTF8(const s: string): string;// as AnsiToUTF8 but more independent of widestringmanager
// file operations
function FileExistsUTF8(const Filename: string): boolean;
function FileAgeUTF8(const FileName: string): Longint;
function DirectoryExistsUTF8(const Directory: string): Boolean;
function ExpandFileNameUTF8(const FileName: string): string;
function ExpandUNCFileNameUTF8(const FileName: string): string;
{$IFNDEF VER2_2_0}
function ExtractShortPathNameUTF8(Const FileName : String) : String;
function FindFirstUTF8(const Path: string; Attr: Longint; out Rslt: TSearchRec): Longint;
function FindNextUTF8(var Rslt: TSearchRec): Longint;
procedure FindCloseUTF8(var F: TSearchrec);
function FileSetDateUTF8(const FileName: String; Age: Longint): Longint;
function FileGetAttrUTF8(const FileName: String): Longint;
function FileSetAttrUTF8(const Filename: String; Attr: longint): Longint;
function DeleteFileUTF8(const FileName: String): Boolean;
function RenameFileUTF8(const OldName, NewName: String): Boolean;
function FileSearchUTF8(const Name, DirList : String): String;
function FileIsReadOnlyUTF8(const FileName: String): Boolean;
function GetCurrentDirUTF8: String;
function SetCurrentDirUTF8(const NewDir: String): Boolean;
function CreateDirUTF8(const NewDir: String): Boolean;
function RemoveDirUTF8(const Dir: String): Boolean;
function ForceDirectoriesUTF8(const Dir: string): Boolean;
// environment
function ParamStrUTF8(Param: Integer): string;
function GetEnvironmentStringUTF8(Index : Integer): String;
function GetEnvironmentVariableUTF8(const EnvVar: String): String;
function GetAppConfigDirUTF8(Global: Boolean): string;</Delphi>
====Mac OS X====
The file functions of the FileUtil unit also take care of a Mac OS X special: OS X normalizes filenames. For example the filename 'ä.txt' can be encoded in unicode with two different sequences (#$C3#$A4 and 'a'#$CC#$88). Under Linux and BSD you can create a filename with both encodings. OS X automatically converts the a umlaut to the three byte sequence. This means:
<Delphi>if Filename1 = Filename2 then ... // is not sufficient under OS X
if AnsiCompareFileName(Filename1, Filename2) = 0 then ... // not sufficient under fpc 2.2.2, even not with cwstring
if CompareFilenames(Filename1, Filename2) = 0 then ... // this always works (unit FileUtil or FileProcs</Delphi>
==UTF8 and source files - the missing BOM==
When you create source files with Lazarus and type some non ascii characters the file is saved in UTF8. It does '''not use BOM''' (Byte Order Mark). You can change the encoding via right click on source editor / File Settings / Encoding. The reason for the lacking BOM is how FPC treats Ansistrings. For compatibility the LCL uses Ansistrings and for portability the LCL uses UTF8.
Note: Some MS Windows text editors might treat the files as system codepage and show them as invalid characters. Do not add the BOM. If you add the BOM you have to change all string assignments.
For example:
<Delphi>Button1.Caption := 'Über';</Delphi>
When no BOM is given (and no codepage parameter was passed) the compiler treats the string as system encoding and copies each byte unconverted to the string. This is how the LCL expects strings.
<Delphi>// source file saved as UTF without BOM
if FileExists('Über.txt') then ; // wrong, because FileExists expects system encoding
if FileExistsUTF8('Über.txt') then ; // correct</Delphi>
==Widestrings and Ansistrings==
When passing Ansistrings to Widestrings you have to convert the encoding.
  w: widestring;
  w:='Über'; // wrong, because FPC will convert system codepage to UTF16
  w:=UTF8ToUTF16('Über'); // correct
==Source file with UTF8 BOM==
If you do a lot of widestring conversions in a unit, the code might become more readable saving the source as UTF8 with BOM. The compiler allows one encoding per unit.
===East Asian languages on Windows===
The default font (Tahoma) for user interface controls under Windows XP is capable of displaying correctly several languages, including arabic, russian and western languages, but not east asian languages, like chinese, japanese and korean. By going to the Control Panel, choosing Regional Settings, clicking on the Languages Tab and installing the East Asia Language Pack, the standard user interface font will simply start showing those languages correctly. Obviously Windows XP versions localized for those languages will already contain this language pack installed. Extended instructions [http://newton.uor.edu/Departments&Programs/AsianStudiesDept/Language/asianlanguageinstallation_XP.html here].
= Unicode essentials =
Unicode standard maps integers from 0 to 10FFFF(h) to characters. Each such mapping is called a code point. In other words, Unicode characters are in principle defined for code points from U+000000 to U+10FFFF (0 to 1 114 111).
There are three schemes for representing Unicode code points as unique byte sequences. These schemes are called Unicode transformation formats: UTF-8, UTF-16 and UTF-32. The conversions between all of them are possible. Here are their basic properties:
                            UTF-8 UTF-16 UTF-32
Smallest code point [hex] 000000 000000 000000
Largest code point  [hex] 10FFFF 10FFFF 10FFFF
Code unit size [bits]          8    16    32
Minimal bytes/character        1      2      4
Maximal bytes/character        4      4      4
'''UTF-8''' has several important and useful properties: It is
interpreted as a sequence of bytes, so that the concept of
lo- and hi-order byte does not exist. Unicode
characters U+0000 to U+007F (ASCII) are encoded simply as
bytes 00h to 7Fh (ASCII compatibility). This means that
files and strings which contain only 7-bit ASCII characters
have the same encoding under both ASCII and UTF-8. All
characters >U+007F are encoded as a sequence of several
bytes, each of which has the two most significant bits set. No
byte sequence of one character is contained within a longer
byte sequence of another character. This allows easy search for substrings. The first byte of a
multibyte sequence that represents a non-ASCII character is
always in the range C0h to FDh and it indicates how many
bytes follow for this character. All further bytes in a
multibyte sequence are in the range 80h to BFh. This allows
easy resynchronization and robustness.
'''UTF-16''' has the following most important properties: It uses a
single 16-bit word to encode characters from U+0000
to U+d7ff, and a pair of 16-bit words to encode any of the
remaining Unicode characters.
Finally, any Unicode character can be represented as a
single 32-bit unit in '''UTF-32'''.
For more, see:
[http://www.unicode.org/faq/basic_q.html Unicode FAQ - Basic questions],
[http://www.unicode.org/faq/utf_bom.html Unicode FAQ - UTF-8, UTF-16, UTF-32 & BOM],
[http://en.wikipedia.org/wiki/UTF-8 Wikipedia: UTF-8]
== Unicode-enabling the win32 interface  ==
=== Guidelines ===
First, and most importantly, all Unicode patches for the Win32 interface must be enclosed by IFDEF WindowsUnicodeSupport, to avoid breaking the existing ANSI interface. After this stabilizes, all ifdefs will be removed and only the Unicode part will remain. At this moment all existing programs that use ANSI characters will need migration to Unicode.
Windows platforms <=Win9x are based on ISO code page
standards and only partially support Unicode. Windows platforms
starting with WinNT and Windows CE fully support Unicode. Win 9x and NT offer two parallel sets of API functions: the old ANSI enabled *A and the new, Unicode enabled *W. *W
functions accept wide strings, i.e. UTF-16 encoded strings, as parameters. Windows CE only uses Wide API functions.
====Wide functions present on Windows 9x====
Some Wide API functions are present on Windows 9x. Here is a list of such functions: http://msdn.microsoft.com/library/default.asp?url=/library/en-us/mslu/winprog/other_existing_unicode_support.asp
Conversion example:
<delphi>GetTextExtentPoint32(hdcNewBitmap, LPSTR(ButtonCaption),
Length(ButtonCaption), TextSize);</delphi>
<delphi>{$ifdef WindowsUnicodeSupport}
  GetTextExtentPoint32W(hdcNewBitmap, PWideChar(Utf8Decode(ButtonCaption)), Length(WideCaption), TextSize);
  GetTextExtentPoint32(hdcNewBitmap, LPSTR(ButtonCaption), Length(ButtonCaption), TextSize);
====Functions that need Ansi and Wide versions====
First Conversion example:
<delphi>function TGDIWindow.GetTitle: String;
l: Integer;
  l := Windows.GetWindowTextLength(Handle);
  SetLength(Result, l);
  Windows.GetWindowText(Handle, @Result[1], l);
<delphi>function TGDIWindow.GetTitle: String;
  l: Integer;
  AnsiBuffer: string;
  WideBuffer: WideString;
{$ifdef WindowsUnicodeSupport}
if UnicodeEnabledOS then
  l := Windows.GetWindowTextLengthW(Handle);
  SetLength(WideBuffer, l);
  l := Windows.GetWindowTextW(Handle, @WideBuffer[1], l);
  SetLength(WideBuffer, l);
  Result := Utf8Encode(WideBuffer);
  l := Windows.GetWindowTextLength(Handle);
  SetLength(AnsiBuffer, l);
  l := Windows.GetWindowText(Handle, @AnsiBuffer[1], l);
  SetLength(AnsiBuffer, l);
  Result := AnsiToUtf8(AnsiBuffer);
  l := Windows.GetWindowTextLength(Handle);
  SetLength(Result, l);
  Windows.GetWindowText(Handle, @Result[1], l);
=== Roadmap ===
==== What should already be working with Unicode: ====
* TForm, TButton, TLabel
* Most controls
* Menus
* LCLIntf.ExtTextOut and most other text related winapis
* TStrings based controls. Examples: TComboBox, TListBox, etc
* SynEdit shows and can input UTF-8 characters correctly
* Setting/Getting unicode strings to/from the ClipBoard
* Setting the Application Title in the project options to (for example) 'Minha Aplicação'.
* Double clicking words with non-ascii chars in the editor to select them
==== Known problems with Unicode support ====
* Many components either do not support RTL or support it incorrectly.
* SynEdit does not support RTL (right to left)
* <s>Is OpenFileDialogCallBack tested with selection large numbers of files?
** Is this problem unicode specific? I think it's a generic problem. --[[User:Sekelsenmat|Sekelsenmat]] 13:40, 14 February 2008 (CET)
*** Maybe. I know I tested it with large number of files before the Unicode version was added. If it is a generic problem, then the the non-Unicode version got broken, when the Unicode version was added. [[User:Vincent|Vincent]] 21:45, 15 February 2008 (CET)
**** Associated bugtracker item: http://bugs.freepascal.org/view.php?id=10918</s> Fixed and implemented.
* <s>class function TWin32WSSelectDirectoryDialog.CreateHandle: Title, FileName and InitialDir should be made Unicode aware.
** Associated bugtracker item: http://bugs.freepascal.org/view.php?id=10919</s> Implemented.
'''Possible problems with Unicode support'''
Based on a code review, the following needs to be tested, because the code doesn't seem to be Unicode aware:
* <s>class procedure TWin32WSCustomComboBox.SetText</s>
* <s>TWin32WSCustomTrayIcon.Show: ATrayIcon.Hint is not Unicode aware</s>
* <s>TWin32WidgetSet.MessageBox doesn't call MessageBoxW.</s>
* TWin32WidgetSet.TextOut: Is Windows.TextOut supported on windows 9X?
** Yes, please see [[LCL_Unicode_Support#Wide_functions_present_on_Windows_9x]]. Althought I never tested this.
* MessageBox buttons don't show unicode correctly when they are translated. Tested on the IDE. Could be a problem on the IDE however.
** Note: I couldn't reproduce using the portuguese translation --[[User:Sekelsenmat|Sekelsenmat]] 22:20, 12 January 2008 (CET)
* (list of unconfirmed problems, if confirmed can be moved to the list above)
=== Screenshots ===
[[Image:Lazarus Unicode Test.png]]
== See Also ==
* [[UTF-8]] - Description of UTF-8 strings

Latest revision as of 00:58, 25 October 2019