The Keyboard Layout Editor
(this entry is a repost, the original was lost in a database mishap.)
As part of the 2008 GSoC program, I worked on a Keyboard Layout Editor for the X.Org Foundation.
The Keyboard Layout Editor (KLE) is an application that allows you to create keyboard layouts for the X.Org server, commonly found in the Linux, OpenSolaris, *BSD, etc Desktops.
My mentor was Sergey Udaltsov, maintainer of xkeyboard-config, the Keyboard Indicator applet in GNOME, supporting libraries for keyboard layouts and much more. I had great help and Sergey was very supportive. Highly recommended mentor for your GSoC’09 project.
The Keyboard Layout Editor showing a layout
The screenshot above shows the main window of the program; a keyboard with blank layout (keys are empty), a section Add to layout with items that can be used to populate the layout, and a section for the description of the layout (Layout details).
There are typically two workflows; first you start off with a blank layout and you add Unicode characters, dead keys, include files, then you save.
The other workflow is to start with an appropriate existing layout as a base, then add more characters, make changes, etc.
It might be strange to talk about different workflows, but in terms of usability it’s important provide assistance for such cases. For example, having tooltips is important when a person starts off with a new layout.
Using the Keyboard Layout Editor
Here we started with a blank layout; we click on Start Character Map, then locate the characters you need, and drag and drop them to the appropriate keys. Each key is composed of four parts, and we number these from 1 to 4. The way we count is quite peculiar,
- bottom left, when you press the key as is (key)
- top left, when you press the key with Shift (Shift + key)
- bottom right, when you press the key with AltGr (AltGr + key)
- top right, when you press the key with Shilft+AltGr (Shift + AltGr + key)
Analysis of a key
This is my entry to the most engineered diagram competition.
The dead keys relate to diacritic marks such as grave and acute. Since they are too small to see, we present them next to a D letter (D for Dead key). In some cases I could not find a character equivalent to the diacritic mark, so I put ?, therefore it looks like D?. If you put the mouse pointer over the key, you can see the full details in the tooltip.
Including files
In many cases, there exist layouts/variants that contain most of the characters you want to add. In this case, you add and enable in the Include files section. You can then override any of those characters by dragging and dropping to the layout.
At this stage in the blog post, it is important to clarify the notions of a layout and a variant. The two are quite similar and the distinction is messy when trying to explain to the end-user. The French layout file is fr, which contains several variants (distinct groups of mappings of physical keys to Unicode characters). When you are actually talking about a French keyboard layout, you are actually referring to the default variant of the «fr» file. Oftentimes people refer to the «fr» file as a whole as the French layout. You can also pick a non-default variant of the layout file, and call it your layout.
The way I would like to define layout and variant is this: a layout refers to the default variant of the layout file. This is consistent to the fact that distributions pick the default variant in the settings so it’s what get the most visibility, or when users select a new layout, they are presented with the default setting first. Regarding layouts in general, it is important for different languages/scripts to make effort that the default layout is updated and includes extra useful and relevant characters.
The new Greek keyboard layout
This is the updated Greek keyboard layout, and is the near-final version that we are planning to submit to xkeyboard-config. It adds Greek Polytonic to the existing Greek layout. It does not make changes to the previous default layout, so users will not be unpleasantly surprised. It also adds all sort of characters that are found in the Greek Unicode block.
In this post I simplified some of the terms/description. If I went a bit too far, please correct me and I’ll update in-place.
Update 8th Sep 08: What are the plans for further development of the layout editor;
- Increase the user base and get more people trying out the editor. This requires some more cleanup of the code, more instructions on how to run it youselves, and get people to provide feedback. An open-source project without users is not a successful project.
- Make it easier for developers to contribute on the project. If you use Eclipse, you can install pydev, antlr3ide, mylyn, subclipse, and you can do the full development from within the cozy Eclipse environment. These need documentation.
- The Issues page at the project has about ten items. This list needs to be reduced.
- The natural place for users of the layout editor is the http://listserv.bat.ru/xkb/List.html mailing list. We need to promote the editor there, and get examples of users actually using it to maintain layouts.
- An issue that plagues some users is when they need compose sequences to generate characters that no pre-composed forms exist. If users really need this (mainly Latin and Cyrillic scripts, complex scripts), it can be adapted to the UI.
- It is technically easy to adapt the editor so that it produces XML layouts. Considering the state of XKB-atkins, this may not be a top priority at the moment. libxml2 comes with the MIT license, so in license terms it would be OK. Not sure if it is OK to link libxml2 to the X.org server. It might actually solve the slow parsing of the configurations files and the issues of xkbcomp.
- At the moment the default geometry is a somewhat generic keyboard. In addition, I deactivated several keys (such as the function keys), in order not to confuse users (you can activate with a small change in the code). The keyboard can be expanded to a full 105-keys style. A related project would be to figure out an efficient way to edit those geometry files, and make the keyboard customised. If people start creating layouts with the editor, they will certainly love to edit geometry files!
Συνέδριο XOrg Developer Summit
Αυτές τις μέρες (αρχές Σεπτεμβρίου 2008) διεξάγεται το συνέδριο XOrg Developer Summit Εδιμβούργο της Σκωτίας.
Διαρκεί 3 μέρες και οι σημειώσεις περιγράφουν τι ειπώθηκε.
Testing the updated IM support in GTK+
In Improving input method support in GTK+-based apps, we talked about some work to update the list of compose sequences that GTK+ knows to the latest version that comes from Xorg. From 691 compose sequences, we now support over 5000.
The patch has landed in GTK+ (trunk), and here are instructions for testing.
- If you have not used jhbuild before, read the jhbuild instructions and install it.
- Add the following to your ~/.jhbuildrc file
branches['gtk+'] = None # Makes sure you build from the trunk of GTK+
- Install gtk+ using the command (see the comment of James on this post on how to avoid Step 5 below)
jhbuild build gtk+
- About 40 minutes later, and about 700MB of space (~600MB for source, ~100MB for installation of files) consumed, you should get a working copy of GTK+ 2.12.
- You can use this compiled version of GTK+ by running
jhbuild shell
This should give you a new shell, and whatever you run from here will use our fresh GTK+. Try running “gedit”. You will notice that the theme is different; it uses the default theme due to the special GTK+. This shell has set special environment variables so that program that run will use the fresh GTK+. The rest of the libraries come from our distribution.
If you try to type compose sequences, you will notice no improvement. This is because at the moment jhbuild builds the branch 2.12 of GTK+ and not trunk. We need to download GTK+ from trunk and rebuild.cd ~/checkout/gnome2/ mv gtk+ gtk+-branch-2.12 svn co svn://svn.gnome.org/svn/gtk+/trunk gtk+ jhbuild build --no-network gtk+Perform Step 4 and get gedit running.
How to test?
- Setup a keyboard layout that supports a good variety of dead keys. My preference is GBr (United Kingdom). Here, AltGr+[];’#/ and AltGr+{}:@~? produce different dead keys. You press one of these combinations and then you press a letter. If such a combination exists, then it gets printed. For example, the old GTK+ produces öõóôòx åōőxxx. The new GTK+ produces öõóôòọ åōőǒŏȯ (12 dead keys).
- Setup Greek, Polytonic (Ancient Greek). The dead keys are [];’ {}:@ AltGr+[] (10 dead keys). Produce characters such as ᾅᾂᾷῗὕὒᾥᾢῷ.
- Try compose sequences as described from the upstream file at XOrg. For example,
ComposeKey+( 1 0 ) produces ⑩. Try the same for 0-20, a-zA-Z.
- Other miscellaneous, Ṩǟấẫǡ (using GBr layout)
The next step would be to parse the list of compose sequences and produce a documentation file.
Keyboard layout for combining diacritics
Typically, if you want to type characters with accents, such as á, ë, ś, you need to configure a suitable keyboard layout that includes compose sequences for those characters. The produced characters are what we call as precomposed characters; which were included in the early stages of Unicode. Nowdays, the idea is that you do not need to define á as a distinct character because it can be represented as a and ´, where the latter is a combining diacritic.
When put together a character and a combining diacritic, they fuse together, producing a seemingly single character. á is a precomposed (really one character), while á is letter a and the combining diacritic called acute (two characters). You can type the latter á by
- Type a
- Press Ctrl+Shift+u, then type 301, then press space bar.
Western languages do not really require combining marks, so the existing keyboard layouts do not use them. Other scripts, such as the Congolese keyboard layout (based on Latin) make good use of them.
This is gedit showing off pango and DejaVu fonts (default font in major distributions).
Line 3 is a bit of an extreme, showing a sandwich of combining diacritics.
Line 4 shows the base character a with the combining diacritics from the Unicode range 0×300 to 0×315.
Both lines 3 and 4 were produced easily with a modified keyboard layout, which is show below.
Line 5 is just me being silly. You can have combining diacritics that enclose your base character.
$ cat /usr/share/X11/xkb/symbols/combining
partial alphanumeric_keys alternate_group
xkb_symbols "combining" {
name[Group1] = "Combining diacritics";
key.type[Group1] = "FOUR_LEVEL";
key <AD11> { [ NoSymbol, NoSymbol, 0x1000300, 0x1000301 ] }; // à á
key <AD12> { [ NoSymbol, NoSymbol, 0x1000302, 0x1000303 ] }; // â ã
key <AC10> { [ NoSymbol, NoSymbol, 0x1000304, 0x1000305 ] }; // ā a̅
key <AC11> { [ NoSymbol, NoSymbol, 0x1000306, 0x1000307 ] }; // ă ȧ
key <BKSL> { [ NoSymbol, NoSymbol, 0x1000308, 0x1000309 ] }; // ä ả
key <AB08> { [ NoSymbol, NoSymbol, 0x1000310, 0x1000311 ] }; // a̐ ȃ
key <AB09> { [ NoSymbol, NoSymbol, 0x1000312, 0x1000313 ] }; // a̒ a̓
key <AB10> { [ NoSymbol, NoSymbol, 0x1000314, 0x1000315 ] }; // a̔ a̕
};
$ diff -u /usr/share/X11/xkb/symbols/us.ORIGINAL /usr/share/X11/xkb/symbols/us
--- /usr/share/X11/xkb/symbols/us.ORIGINAL 2008-02-20 11:11:13.000000000 +0000
+++ /usr/share/X11/xkb/symbols/us 2008-02-20 13:02:07.000000000 +0000
@@ -492,3 +492,12 @@
name[Group1]= "U.S. English - Macintosh";
};
+partial alphanumeric_keys modifier_keys
+xkb_symbols "combining_us" {
+
+ include "us"
+ include "combining"
+
+ key.type[Group1] = "FOUR_LEVEL";
+ name[Group1] = "U.S. English - Combining";
+};
$ diff -u /usr/share/X11/xkb/rules/xorg.xml.ORIGINAL /usr/share/X11/xkb/rules/xorg.xml
--- /usr/share/X11/xkb/rules/xorg.xml.ORIGINAL 2008-02-20 11:27:00.000000000 +0000
+++ /usr/share/X11/xkb/rules/xorg.xml 2008-02-20 11:27:48.000000000 +0000
@@ -3643,6 +3643,12 @@
<description xml:lang="zh_TW">Macintosh</description>
</configItem>
</variant>
+ <variant>
+ <configItem>
+ <name>combining_us</name>
+ <description>Combining</description>
+ </configItem>
+ </variant>
</variantList>
</layout>
<layout>
$ _
Then, you select this keyboard layout (U.S. English) and variant (Combining) in the Keyboard Indicator applet.
Unlike dead keys, with combining diacritics you first type the base character (such as a) and then any combining diacritics.
Our sample layout variant puts the diacritics in the physical keys for [];’#,./. For example,
- a + AltGr+[ : à
- a + AltGr+Shift+[ : á
- a + AltGr+[ + AltGr+’ : ằ
If your language has needs that can be solved with combining diacritics, this is how they are solved.
It is quite important to create keyboard layouts for all languages, and actually make good use of them.
