Bedienungsanleitung Kompozer 07 (Seite 49 von 58) (Englisch)

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KompoZer User Guide — 17 December 2007 Based on version 0.7.10 49

A6.3.6 UTF encodings

ISO-8859 is fine when using one language at a time

but becomes clumsy and slow when languages are

mixed. UTF coding releases us from this restriction and

provides a mechanism for addressing the full range of

Unicode characters quickly. KompoZer allows coding in

either UTF-8, UTF-16 or UTF-32 formats which are

based on units of 8, 16 or 32 bits respectively. UTF-32

is not usually used for coding web pages.

UTF-8 uses 1 to 4 bytes to represent a character. It

uses 1 byte to represent characters in the ASCII set,

two bytes for the next 1920 characters (including the

Latin alphabet characters with diacritics, Greek,

Cyrillic, Coptic, Armenian, Hebrew, and Arabic charac-

ters) and three bytes for the rest of 65,000 characters

in the Basic Multilingual plane (BMP). Supplementary

characters use 4 bytes.

UTF-16 uses 2 bytes for any character in the BMP,

and 4 bytes for supplementary characters.

UTF-32 uses 4 bytes for all characters

KompoZer offers additional practical advantages

when UTF-8 encoding is used for pages with multiple

languages. Irrespective of the encoding in use in Nor-

mal or Preview mode KompoZer depicts all characters

correctly using the corresponding 'glyph'. In source

view encodings which require characters to be repre-

sented as character references show the character

reference. This reduces readability significantly. With

UTF encoding all characters can be represented as

glyphs so the problem is avoided.

A6.3.7 Symbols

Traditionally computers have relied on special fonts

like ‘Symbol’ or ‘Wingdings’ to produce symbols. This is

not necessary on web pages. Since such fonts do not

support Unicode any attempt to use them will yield

unreliable results which may vary from browser to

browser.

Fortunately Unicode supports a large range of sym-

bols which fulfills many needs.

Inputting special symbols

There are several ways of inserting symbols into a

page using KompoZer.

1 Via the Insert menu. Using Insert > Characters

and Symbols. Covers accented characters and a

number of other common symbols

2 Using Windows Character Map. Using the stand-

ard font in use find the symbol required, select

and copy it, then in KompoZer paste it as re-

quired. Recent versions of Character map allow

you to group characters by Unicode subrange

which makes it easier to find a particular symbol

3 If you use a particular symbol frequently it may

be easier to insert it by keystroke. Several char-

acters permit this and, where it can be done, the

keystroke is shown at the bottom right corner of

Character Map. The euro symbol, €, for instance,

may be inserted using ALT+0128

4 AllChars [Ref21] is a useful utility that allows

any program to insert any Windows-1282 (see

below) character using a few easily discovered

keystrokes

5 In KompoZer Source view any character may be

inserted using the Numeric character reference.

In the bottom left corner of Character Map this

is given in hex format. Thus for euro you insert

€

Note The code is shown in Character map as

U+20AC This is the conventional way of repre-

senting Unicode characters i.e. by 'U+' followed

by the hexadecimal code point

6 In source view, entity references may be inserted

similarly. Many are easy to memorise e.g. €

> <

The first four methods can be used in normal or

preview mode, the last two in source view.

Table A6.3-4

Some useful symbols

Symbol Key code Unicode

En dash – alt+0150 U+2013

Em dash — alt+0151 U+2014

ellipsis ... alt+0133 U+2026

Left single quote ‘ alt+0145 U+2018

Right single quote ’ alt+0146 U+2019

Left double quote “ alt+0147 U+201C

Right double quote ” alt+0148 U+201D

Euro € alt+0128 U+20AC

Pound £ alt+0163 U+00A3

Degree sign ° alt+0176 U+00B0

Multiply sign × alt+0215 U+00D7;

Divide sign ÷ alt+0247 U+00F7;

The keen-eyed may observe that the key codes are

neither the character codes nor the Unicode code

points for the character required. In fact they are the

(decimal) character codes derived from Windows-1252

encoding. KompoZer will convert these to whatever

code is appropriate depending on the encoding selected

and the character involved. (So the key code never

appears in the source.) Incidentally Windows-1252 [Ref

13] encoding is a possible alternative to ISO-8859-1

suitable for western languages. It increases the

number of available character codes to 218 characters

by re-allocating some of the codes in the range 80 to 9F

which are normally unused.

Alan Wood's website [Ref 2] is a useful resource

listing entities (where defined) and Numeric character

references for a large number of characters from the

Monotype Typography Symbol font (as on Windows XP)

including Greek, Mathematical and Punctuation [Ref 6]

and also the Microsoft Wingdings font [Ref 7]. (For

Windings in several cases there is no Unicode equiva-

lent.)

A6.3.8 Unicode support

A6.3.8.1 Fonts

Although Unicode offers tremendous potential the

usual caveats apply when choosing fonts. See for in-

stance section 4.2.1.1 but, in this case, it is important

to check that all fonts in the list include the characters

required. No font covers the full range of Unicode, or

even a small single digit percentage of it. To check the

supported Unicode ranges of a font Microsoft supply an

extension [Ref 12] for Windows Explorer. With it in-

stalled, right-click any TrueType (TTF) font file in Win-

dows Explorer and select the Properties tab. Particular

characters can be searched for using Character map.

Checking for support is more than usually difficult

if unusual characters are required. Compatible fonts

must be installed on any visitor's computer and, where

in a style sheet the font-family is specified as a priori-

tised list of font family names (as it should be), ideally

all fonts in the list should be checked.

Kompozer 07 Seite 49

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