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Move GConvert docs inline
This commit is contained in:
Matthias Clasen
parent
f837e15972
commit
def0dc01f7
@ -2,159 +2,10 @@
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Character Set Conversion
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<!-- ##### SECTION Short_Description ##### -->
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convert strings between different character sets using iconv()
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<!-- ##### SECTION Long_Description ##### -->
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<para>
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</para>
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<refsect2 id="file-name-encodings">
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<title>File Name Encodings</title>
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<para>
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Historically, Unix has not had a defined encoding for file
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names: a file name is valid as long as it does not have path
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separators in it ("/"). However, displaying file names may
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require conversion: from the character set in which they were
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created, to the character set in which the application
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operates. Consider the Spanish file name
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"<filename>Presentación.sxi</filename>". If the
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application which created it uses ISO-8859-1 for its encoding,
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then the actual file name on disk would look like this:
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</para>
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<programlisting id="filename-iso8859-1">
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Character: P r e s e n t a c i ó n . s x i
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Hex code: 50 72 65 73 65 6e 74 61 63 69 f3 6e 2e 73 78 69
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</programlisting>
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<para>
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However, if the application use UTF-8, the actual file name on
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disk would look like this:
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</para>
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<programlisting id="filename-utf-8">
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Character: P r e s e n t a c i ó n . s x i
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Hex code: 50 72 65 73 65 6e 74 61 63 69 c3 b3 6e 2e 73 78 69
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</programlisting>
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<para>
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Glib uses UTF-8 for its strings, and GUI toolkits like GTK+
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that use Glib do the same thing. If you get a file name from
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the file system, for example, from
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<function>readdir(3)</function> or from <link
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linkend="g_dir_read_name"><function>g_dir_read_name()</function></link>,
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and you wish to display the file name to the user, you
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<emphasis>will</emphasis> need to convert it into UTF-8. The
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opposite case is when the user types the name of a file he
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wishes to save: the toolkit will give you that string in
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UTF-8 encoding, and you will need to convert it to the
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character set used for file names before you can create the
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file with <function>open(2)</function> or
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<function>fopen(3)</function>.
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</para>
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<para>
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By default, Glib assumes that file names on disk are in UTF-8
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encoding. This is a valid assumption for file systems which
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were created relatively recently: most applications use UTF-8
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encoding for their strings, and that is also what they use for
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the file names they create. However, older file systems may
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still contain file names created in "older" encodings, such as
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ISO-8859-1. In this case, for compatibility reasons, you may
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want to instruct Glib to use that particular encoding for file
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names rather than UTF-8. You can do this by specifying the
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encoding for file names in the <link
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linkend="G_FILENAME_ENCODING"><envar>G_FILENAME_ENCODING</envar></link>
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environment variable. For example, if your installation uses
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ISO-8859-1 for file names, you can put this in your
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<filename>~/.profile</filename>:
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</para>
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<programlisting>
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export G_FILENAME_ENCODING=ISO-8859-1
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</programlisting>
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<para>
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Glib provides the functions <link
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linkend="g_filename_to_utf8"><function>g_filename_to_utf8()</function></link>
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and <link
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linkend="g_filename_from_utf8"><function>g_filename_from_utf8()</function></link>
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to perform the necessary conversions. These functions convert
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file names from the encoding specified in
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<envar>G_FILENAME_ENCODING</envar> to UTF-8 and vice-versa.
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<xref linkend="file-name-encodings-diagram"/> illustrates how
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these functions are used to convert between UTF-8 and the
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encoding for file names in the file system.
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</para>
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<figure id="file-name-encodings-diagram">
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<title>Conversion between File Name Encodings</title>
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<graphic fileref="file-name-encodings.png" format="PNG"/>
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</figure>
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<refsect3 id="file-name-encodings-checklist">
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<title>Checklist for Application Writers</title>
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<para>
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This section is a practical summary of the detailed
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description above. You can use this as a checklist of
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things to do to make sure your applications process file
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name encodings correctly.
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</para>
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<orderedlist>
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<listitem>
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<para>
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If you get a file name from the file system from a
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function such as <function>readdir(3)</function> or
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<function>gtk_file_chooser_get_filename()</function>,
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you do not need to do any conversion to pass that
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file name to functions like <function>open(2)</function>,
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<function>rename(2)</function>, or
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<function>fopen(3)</function> — those are "raw"
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file names which the file system understands.
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</para>
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</listitem>
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<listitem>
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<para>
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If you need to display a file name, convert it to UTF-8
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first by using <link
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linkend="g_filename_to_utf8"><function>g_filename_to_utf8()</function></link>.
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If conversion fails, display a string like
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"<literal>Unknown file name</literal>". <emphasis>Do
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not</emphasis> convert this string back into the
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encoding used for file names if you wish to pass it to
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the file system; use the original file name instead.
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For example, the document window of a word processor
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could display "Unknown file name" in its title bar but
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still let the user save the file, as it would keep the
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raw file name internally. This can happen if the user
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has not set the <envar>G_FILENAME_ENCODING</envar>
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environment variable even though he has files whose
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names are not encoded in UTF-8.
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</para>
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</listitem>
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<listitem>
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<para>
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If your user interface lets the user type a file name
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for saving or renaming, convert it to the encoding used
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for file names in the file system by using <link
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linkend="g_filename_from_utf8"><function>g_filename_from_utf8()</function></link>.
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Pass the converted file name to functions like
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<function>fopen(3)</function>. If conversion fails, ask
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the user to enter a different file name. This can
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happen if the user types Japanese characters when
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<envar>G_FILENAME_ENCODING</envar> is set to
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<literal>ISO-8859-1</literal>, for example.
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</para>
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</listitem>
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</orderedlist>
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</refsect3>
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</refsect2>
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<!-- ##### SECTION See_Also ##### -->
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<para>
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@ -200,9 +51,7 @@ export G_FILENAME_ENCODING=ISO-8859-1
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<!-- ##### STRUCT GIConv ##### -->
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<para>
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The <structname>GIConv</structname> struct wraps an
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<function>iconv()</function> conversion descriptor. It contains private data
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and should only be accessed using the following functions.
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</para>
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@ -222,9 +71,7 @@ and should only be accessed using the following functions.
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<!-- ##### MACRO G_CONVERT_ERROR ##### -->
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<para>
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Error domain for character set conversions. Errors in this domain will
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be from the #GConvertError enumeration. See #GError for information on
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error domains.
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</para>
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@ -342,16 +189,15 @@ error domains.
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<!-- ##### ENUM GConvertError ##### -->
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<para>
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Error codes returned by character set conversion routines.
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</para>
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@G_CONVERT_ERROR_NO_CONVERSION: Conversion between the requested character sets
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is not supported.
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@G_CONVERT_ERROR_ILLEGAL_SEQUENCE: Invalid byte sequence in conversion input.
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@G_CONVERT_ERROR_FAILED: Conversion failed for some reason.
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@G_CONVERT_ERROR_PARTIAL_INPUT: Partial character sequence at end of input.
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@G_CONVERT_ERROR_BAD_URI: URI is invalid.
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@G_CONVERT_ERROR_NOT_ABSOLUTE_PATH: Pathname is not an absolute path.
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@G_CONVERT_ERROR_NO_CONVERSION:
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@G_CONVERT_ERROR_ILLEGAL_SEQUENCE:
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@G_CONVERT_ERROR_FAILED:
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@G_CONVERT_ERROR_PARTIAL_INPUT:
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@G_CONVERT_ERROR_BAD_URI:
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@G_CONVERT_ERROR_NOT_ABSOLUTE_PATH:
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<!-- ##### FUNCTION g_get_charset ##### -->
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<para>
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121
glib/gconvert.c
121
glib/gconvert.c
@ -56,6 +56,127 @@
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#endif
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/**
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* SECTION:conversions
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* @title: Character Set Conversion
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* @short_description: Convert strings between different character sets
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*
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* The g_convert() family of function wraps the functionality of iconv(). In
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* addition to pure character set conversions, GLib has functions to deal
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* with the extra complications of encodings for file names.
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*
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* <refsect2 id="file-name-encodings">
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* <title>File Name Encodings</title>
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* <para>
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* Historically, Unix has not had a defined encoding for file
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* names: a file name is valid as long as it does not have path
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* separators in it ("/"). However, displaying file names may
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* require conversion: from the character set in which they were
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* created, to the character set in which the application
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* operates. Consider the Spanish file name
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* "<filename>Presentación.sxi</filename>". If the
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* application which created it uses ISO-8859-1 for its encoding,
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* </para>
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* <programlisting id="filename-iso8859-1">
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* Character: P r e s e n t a c i ó n . s x i
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* Hex code: 50 72 65 73 65 6e 74 61 63 69 f3 6e 2e 73 78 69
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* </programlisting>
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* <para>
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* However, if the application use UTF-8, the actual file name on
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* disk would look like this:
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* </para>
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* <programlisting id="filename-utf-8">
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* Character: P r e s e n t a c i ó n . s x i
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* Hex code: 50 72 65 73 65 6e 74 61 63 69 c3 b3 6e 2e 73 78 69
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* </programlisting>
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* <para>
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* Glib uses UTF-8 for its strings, and GUI toolkits like GTK+
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* that use Glib do the same thing. If you get a file name from
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* the file system, for example, from readdir(3) or from g_dir_read_name(),
|
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* and you wish to display the file name to the user, you
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* emphasis>will</emphasis> need to convert it into UTF-8. The
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* opposite case is when the user types the name of a file he
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* wishes to save: the toolkit will give you that string in
|
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* UTF-8 encoding, and you will need to convert it to the
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* character set used for file names before you can create the
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* file with open(2) or fopen(3).
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* </para>
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* <para>
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* By default, Glib assumes that file names on disk are in UTF-8
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* encoding. This is a valid assumption for file systems which
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* were created relatively recently: most applications use UTF-8
|
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* encoding for their strings, and that is also what they use for
|
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* the file names they create. However, older file systems may
|
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* still contain file names created in "older" encodings, such as
|
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* ISO-8859-1. In this case, for compatibility reasons, you may
|
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* want to instruct Glib to use that particular encoding for file
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* names rather than UTF-8. You can do this by specifying the
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* encoding for file names in the <link
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* linkend="G_FILENAME_ENCODING"><envar>G_FILENAME_ENCODING</envar></link>
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* environment variable. For example, if your installation uses
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* ISO-8859-1 for file names, you can put this in your
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* <filename>~/.profile</filename>:
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* </para>
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* <programlisting>
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* export G_FILENAME_ENCODING=ISO-8859-1
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* </programlisting>
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* <para>
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* Glib provides the functions g_filename_to_utf8() and
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* g_filename_from_utf8() to perform the necessary conversions. These
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* functions convert file names from the encoding specified in
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* <envar>G_FILENAME_ENCODING</envar> to UTF-8 and vice-versa.
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* <xref linkend="file-name-encodings-diagram"/> illustrates how
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* these functions are used to convert between UTF-8 and the
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* encoding for file names in the file system.
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* </para>
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* <figure id="file-name-encodings-diagram">
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* <title>Conversion between File Name Encodings</title>
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* <graphic fileref="file-name-encodings.png" format="PNG"/>
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* </figure>
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* <refsect3 id="file-name-encodings-checklist">
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* <title>Checklist for Application Writers</title>
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* <para>
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* This section is a practical summary of the detailed
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* description above. You can use this as a checklist of
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* things to do to make sure your applications process file
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* name encodings correctly.
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* </para>
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* <orderedlist>
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* <listitem><para>
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* If you get a file name from the file system from a function
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* such as readdir(3) or gtk_file_chooser_get_filename(),
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* you do not need to do any conversion to pass that
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* file name to functions like open(2), rename(2), or
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* fopen(3) — those are "raw" file names which the file
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* system understands.
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* </para></listitem>
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* <listitem><para>
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* If you need to display a file name, convert it to UTF-8 first by
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* using g_filename_to_utf8(). If conversion fails, display a string like
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* "<literal>Unknown file name</literal>". <emphasis>Do not</emphasis>
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* convert this string back into the encoding used for file names if you
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* wish to pass it to the file system; use the original file name instead.
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* For example, the document window of a word processor could display
|
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* "Unknown file name" in its title bar but still let the user save the
|
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* file, as it would keep the raw file name internally. This can happen
|
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* if the user has not set the <envar>G_FILENAME_ENCODING</envar>
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* environment variable even though he has files whose names are not
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* encoded in UTF-8.
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* </para></listitem>
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* <listitem><para>
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* If your user interface lets the user type a file name for saving or
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* renaming, convert it to the encoding used for file names in the file
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* system by using g_filename_from_utf8(). Pass the converted file name
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* to functions like fopen(3). If conversion fails, ask the user to enter
|
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* a different file name. This can happen if the user types Japanese
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* characters when <envar>G_FILENAME_ENCODING</envar> is set to
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* <literal>ISO-8859-1</literal>, for example.
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* </para></listitem>
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* orderedlist>
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* </refsect3>
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* </refsect2>
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*/
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/* We try to terminate strings in unknown charsets with this many zero bytes
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* to ensure that multibyte strings really are nul-terminated when we return
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* them from g_convert() and friends.
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@ -35,7 +35,19 @@
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G_BEGIN_DECLS
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typedef enum
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/**
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* GConvertError:
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* @G_CONVERT_ERROR_NO_CONVERSION: Conversion between the requested character
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* sets is not supported.
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* @G_CONVERT_ERROR_ILLEGAL_SEQUENCE: Invalid byte sequence in conversion input.
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* @G_CONVERT_ERROR_FAILED: Conversion failed for some reason.
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* @G_CONVERT_ERROR_PARTIAL_INPUT: Partial character sequence at end of input.
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* @G_CONVERT_ERROR_BAD_URI: URI is invalid.
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* @G_CONVERT_ERROR_NOT_ABSOLUTE_PATH: Pathname is not an absolute path.
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*
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* Error codes returned by character set conversion routines.
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*/
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typedef enum
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{
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G_CONVERT_ERROR_NO_CONVERSION,
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G_CONVERT_ERROR_ILLEGAL_SEQUENCE,
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@ -45,10 +57,22 @@ typedef enum
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G_CONVERT_ERROR_NOT_ABSOLUTE_PATH
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} GConvertError;
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/**
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* G_CONVERT_ERROR:
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*
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* Error domain for character set conversions. Errors in this domain will
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* be from the #GConvertError enumeration. See #GError for information on
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* error domains.
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*/
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#define G_CONVERT_ERROR g_convert_error_quark()
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GQuark g_convert_error_quark (void);
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/* Thin wrappers around iconv
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/**
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* GIconv:
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*
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* The <structname>GIConv</structname> struct wraps an
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* iconv() conversion descriptor. It contains private data
|
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* and should only be accessed using the following functions.
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*/
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typedef struct _GIConv *GIConv;
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Reference in New Issue
Block a user