path: root/docs/EXTENDING.txt

                                   Tux Paint
                                 version 0.9.22
                              Extending Tux Paint

                Copyright 2002-2009 by Bill Kendrick and others
                               New Breed Software

                           bill@newbreedsoftware.com
                            http://www.tuxpaint.org/

                          June 14, 2002 - July 1, 2009

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   If you wish to add or change things like Brushes and Rubber Stamps used by
   Tux Paint, you can do it fairly easily by simply putting or removing files
   on your hard disk.

   Note: You'll need to restart Tux Paint for the changes to take effect.

Where Files Go

  Standard Files

       Tux Paint looks for its various data files in its 'data' directory.

    Linux and Unix

         Where this directory goes depends on what value was set for
         "DATA_PREFIX" when Tux Paint was built. See INSTALL.txt for details.

         By default, though, the directory is:

           /usr/local/share/tuxpaint/

         If you installed from a package, it is more likely to be:

           /usr/share/tuxpaint/

    Windows

         Tux Paint looks for a directory called 'data' in the same directory
         as the executable. This is the directory that the installer used
         when installing Tux Paint e.g.:

           C:\Program Files\TuxPaint\data

    Mac OS X

         Tux Paint stores its data files inside the "Tux Paint" application
         (which is actually a special kind of folder on Mac OS X). The
         following steps explain how to get to the folders within:

          1. Bring up a 'context' menu by holding the [Control] key and
             clicking the Tux Paint icon the in Finder. (If you have a mouse
             with more than one button, you can simply right-click the icon.)
          2. Select "Show Contents" from the menu that appears. A new Finder
             window will appear with a folder inside called "Contents."
          3. Open the "Contents" folder and open the "Resources" folder found
             inside.
          4. There, you will find the "starters", "stamps" and "brushes"
             folders. Adding new content to these folders will make the
             content available to any user that launches this copy (icon) of
             Tux Paint.

         Note: If you install a newer version of Tux Paint and replace or
         discard the old version, you will lose changes made by following the
         instructions above, so keep backups of your new content (stamps,
         brushes, etc.).

         Tux Paint also looks for files in a "TuxPaint" folder that you can
         place in your system's "Application Support" folder (found under
         "Library" at the root of your hard disk):

           /Library/Application Support/TuxPaint/

         It also looks for files in the user's "Application Support" folder:

           /Users/(user name)/Library/Application Support/TuxPaint/

         When you upgrade to a newer version of Tux Paint, the contents of
         this TuxPaint folder will stay the same and remain accessible by all
         users of Tux Paint.

     ----------------------------------------------------------------------

  Personal Files

       You can also create brushes, stamps, fonts and 'starters' in your own
       directory (folder) for Tux Paint to find.

    Windows

         Your personal Tux Paint folder is stored in your "Application Data".
         For example, on newer Windows (set up for an English-speaking user):

           C:\Documents and Settings\(user name)\Application Data\TuxPaint\

    Mac OS X

         Your personal Tux Paint folder is stored in your "Application
         Support" folder:

           /Users/(user name)/Library/Application Support/ TuxPaint/

    Linux and Unix

         Your personal Tux Paint directory is "$(HOME)/.tuxpaint/" (also
         known as "~/.tuxpaint/".

         That is, if your home directory is "/home/karl", then your Tux Paint
         directory is "/home/karl/.tuxpaint/".

         Don't forget the period (".") before the 'tuxpaint'!

       To add brushes, stamps fonts, and 'starters,' create subdirectories
       under your personal Tux Paint directory named "brushes", "stamps",
       "fonts" and "starters" respectively.

       (For example, if you created a brush named "flower.png", you would put
       it in "~/.tuxpaint/brushes/" under Linux or Unix.)

     ----------------------------------------------------------------------

Brushes

     The brushes used for drawing with the 'Brush' and 'Lines' tools in
     Tux Paint are simply PNG image files.

     The alpha (transparency) of the PNG image is used to determine the shape
     of the brush, which means that the shape can be 'anti-aliased' and even
     partially-transparent!

     Greyscale pixels in the brush PNG will be drawn using the
     currently-selected color in Tux Paint. Color pixels will be tinted.

     Brush images should be no wider than 40 pixels across and no taller than
     40 pixels high. (i.e., the maximum size can be 40 x 40.)

  Brush Options

       Aside from a graphical shape, brushes can also be given other
       attributes. To do this, you need to create a 'data file' for the
       brush.

       A brush data file is simply a text file containing the options.

       The file has the same name as the PNG image, but a ".dat" extension.
       (e.g., "brush.png"'s data file is the text file "brush.dat" in the
       same directory.)

    Brush Spacing

         As of Tux Paint version 0.9.16, you can now specify the spacing for
         brushes (that is, how often they are drawn). By default, the spacing
         will be the brush's height, divided by 4.

         Add a line containing the line "spacing=N" to the brush's data file,
         where N is the spacing you want for the brush. (The lower the
         number, the more often the brush is drawn.)

    Animated Brushes

         As of Tux Paint version 0.9.16, you may now create animated brushes.
         As the brush is used, each frame of the animation is drawn.

         Lay each frame out across a wide PNG image. For example, if your
         brush is 30x30 and you have 5 frames, the image should be 150x30.

         Add a line containing the line "frames=N" to the brush's data file,
         where N is the number of frames in the brush.

         Note: If you'd rather the frames be flipped through randomly, rather
         than sequentially, also add a line containing "random" to the
         brush's data file.

    Directional Brushes

         As of Tux Paint version 0.9.16, you may now create directional
         brushes. As the brush is used, different shapes are drawn, depending
         on the direction the brush is going.

         The directional shapes are divided into a 3x3 square in a PNG image.
         For example, if your brush is 30x30, the image should be 90x90, and
         each of the direction's shapes placed in a 3x3 grid. The center
         region is used for no motion. The top right is used for motion
         that's both up, and to the right. And so on.

         Add a line containing the line "directional" to the brush's data
         file.

    Animated Directional Brushes

         You may mix both animated and directional features into one brush.
         Use both options ("frames=N" and "directional"), in separate lines
         in the brush's "".dat" file.

         Lay the brush out so that each 3x3 set of directional shapes are
         laid out across a wide PNG image. For example, if the brush is 30x30
         and there are 5 frames, it would be 450x90. (The leftmost 150x90
         pixels of the image represent the 9 direction shapes for the first
         frame, for example.)

     Place the brush image PNGs (and any data text files) in the "brushes"
     directory.

     Note: If your new brushes all come out as solid squares or rectangles,
     it's because you forgot to use alpha transparency! See the documentation
     file "PNG.txt" for more information and tips.

     ----------------------------------------------------------------------

Stamps

     All stamp-related files go in the "stamps" directory. It's useful to
     create subdirectories and sub-subdirectories there to organize the
     stamps. (For example, you can have a "holidays" folder with "halloween"
     and "christmas" sub-folders.)

  Images

       Rubber Stamps in Tux Paint can be made up of a number of separate
       files. The one file that is required is, of course, the picture
       itself.

       As of Tux Paint version 0.9.17, Stamps may be either PNG bitmap images
       or SVG vector images. They can be full-color or greyscale. The alpha
       (transparency) channel of PNGs is used to determine the actual shape
       of the picture (otherwise you'll stamp a large rectangle on your
       drawings).

       PNGs can be any size, and Tux Paint (by default) provides a set of
       sizing buttons to let the user scale the stamp up (larger) and down
       (smaller).

       SVGs are vector-based, and will be scaled appropriately for the canvas
       being used in Tux Paint.

       Note: If your new PNG stamps all have solid rectangular-shaped
       outlines of a solid color (e.g., white or black), it's because you
       forgot to use alpha transparency! See the documentation file "PNG.txt"
       for more information and tips.

       Note: If your new SVG stamps seem to have a lot of whitespace, make
       sure the SVG 'document' is no larger than the shape(s) within. If they
       are being clipped, make sure the 'document' is large enough to contain
       the shape(s). See the documentation file "SVG.txt" for more
       information and tips.

       Advanced Users: The Advanced Stamps HOWTO describes, in detail, how to
       make PNG images which will scale perfectly when used as stamps in
       Tux Paint.

     ----------------------------------------------------------------------

  Description Text

       Text (".TXT") files with the same name as the PNG or SVG. (e.g.,
       "picture.png"'s description is stored in "picture.txt" in the same
       directory.)

       The first line of the text file will be used as the US English
       description of the stamp's image. It must be encoded in UTF-8.

    Language Support

         Additional lines can be added to the text file to provide
         translations of the description, to be displayed when Tux Paint is
         running in a different locale (like French or Spanish).

         The beginning of the line should correspond to the language code of
         the language in question (e.g., "fr" for French, and "zh_TW" for
         Traditional Chinese), followed by ".utf8=" and the translated
         description (encoded in UTF-8).

         There are scripts in the "po" directory for converting the text
         files to PO format (and back) for easy translation to different
         languages. Therefore you should never add or change translations in
         the .txt files directly.

         If no translation is available for the language Tux Paint is
         currently running in, the US English text is used.

    Windows Users

         Use NotePad or WordPad to edit/create these files. Be sure to save
         them as Plain Text, and make sure they have ".txt" at the end of the
         filename...

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  Sound Effects

       WAVE (".wav") or OGG Vorbis (".ogg") files with the same name as the
       PNG or SVG. (e.g., "picture.svg"'s sound effect is the sound file
       "picture.wav" in the same directory.)

    Language Support

         For sounds for different locales (e.g., if the sound is someone
         saying a word, and you want translated versions of the word said),
         also create WAV or OGG files with the locale's label in the
         filename, in the form: "STAMP_LOCALE.EXT"

         "picture.png"'s sound effect, when Tux Paint is run in Spanish mode,
         would be "picture_es.wav". In French mode, "picture_fr.wav". In
         Brazilian Portuguese mode, "picture_pt_BR.wav". And so on...

         If no localized sound effect can be loaded, Tux Paint will attempt
         to load the 'default' sound file. (e.g., "picture.wav")

       Note: For descriptive sounds (not sound effects, like a bang or a bird
       chirping), consider using the Descriptive Sounds, described below.

     ----------------------------------------------------------------------

  Descriptive Sound

       WAVE (".wav") or OGG Vorbis (".ogg") files with the same name as the
       PNG or SVG, followed by "_desc" (e.g., "picture.svg"'s descriptive
       sound is the sound file "picture_desc.ogg" in the same directory.)

    Language Support

         For descriptions in different languages, also create WAV or OGG
         files with both "_desc" and the locale's label in the filename, in
         the form: "STAMP_desc_LOCALE.EXT"

         "picture.png"'s descriptive sound, when Tux Paint is run in Spanish
         mode, would be "picture_desc_es.wav". In French mode,
         "picture_desc_fr.wav". In Brazilian Portuguese mode,
         "picture_desc_br_PT.wav". And so on...

         If no localized descriptive sound can be loaded, Tux Paint will
         attempt to load the 'default' descriptive sound file. (e.g.,
         "picture_desc.wav")

     ----------------------------------------------------------------------

  Stamp Options

       Aside from a graphical shape, a textual description, and a sound
       effect, stamps can also be given other attributes. To do this, you
       need to create a 'data file' for the stamp.

       A stamp data file is simply a text file containing the options.

       The file has the same name as the PNG or SVG image, but a ".dat"
       extension. (e.g., "picture.png"'s data file is the text file
       "picture.dat" in the same directory.)

    Colored Stamps

         Stamps can be made to be either "colorable" or "tintable."

      Colorable

           "Colorable" stamps they work much like brushes - you pick the
           stamp to get the shape, and then pick the color you want it to be.
           (Symbol stamps, like the mathematical and musical ones, are an
           example.)

           Nothing about the original image is used except the transparency
           (from "alpha" channel). The color of the stamp comes out solid.

           Add a line containing the word "colorable" to the stamp's data
           file.

      Tinted

           "Tinted" stamps are similar to "colorable" ones, except the
           details of the original image are kept. (To put it technically,
           the original image is used, but its hue is changed, based on the
           currently-selected color.)

           Add a line containing the word "tintable" to the stamp's data
           file.

        Tinting Options:

             Depending on the contents of your stamp, you might want to have
             Tux Paint use one of a numer of methods when tinting it. Add one
             of the following lines to the stamp's data file:

             "tinter=normal" (default)
                     This is the normal tinting mode. (Hue range is
                     +/- 18 degrees, 27 replace.)

             "tinter=anyhue"
                     This remaps all hues in the stamp. (Hue range is
                     +/- 180 degrees.)

             "tinter=narrow"
                     This like 'anyhue', but a narrower hue angle. (Hue range
                     is +/- 6 degrees, 9 replace.)

             "tinter=vector"
                     This is map 'black through white' to 'black through
                     destination'.

    Unalterable Stamps

         By default, a stamp can be flipped upside down, shown as a mirror
         image, or both. This is done using the control buttons below the
         stamp selector, at the lower right side of the screen in Tux Paint.

         Sometimes, it doesn't make sense for a stamp to be flippable or
         mirrored; for example, stamps of letters or numbers. Sometimes
         stamps are symmetrical, so letting the user flip or mirror them
         isn't useful.

         To make a stamp un-flippable, add the option "noflip" to the stamp's
         data file.

         To keep a stamp from being mirrored, add a line containing the word
         "nomirror" to the stamp's data file.

    Initial Stamp Size

         By default, Tux Paint assumes that your stamp is sized appropriately
         for unscaled display on a 608x472 canvas. This is the original
         Tux Paint canvas size, provided by a 640x480 screen. Tux Paint will
         then adjust the stamp according to the current canvas size and, if
         enabled, the user's stamp size controls.

         If your stamp would be too big or too small, you can specify a scale
         factor. If your stamp would be 2.5 times as wide (or tall) as it
         should be, add the option "scale 40%" or "scale 5/2" or "scale 2.5"
         or "scale 2:5" to your image. You may include an "=" if you wish, as
         in "scale=40%".

    Windows Users

         You can use NotePad or WordPad to create these file. Be sure to save
         it as Plain Text, and make sure the filename has ".dat" at the end,
         and not ".txt"...

  Pre-Mirrored and Flipped Images

       In some cases, you may wish to provide a pre-drawn version of a
       stamp's mirror-image, flipped image, or even both. For example,
       imagine a picture of a fire truck with the words "Fire Department"
       written across the side. You probably do not want that text to appear
       backwards when the image is flipped!

       To create a mirrored version of a stamp that you want Tux Paint to
       use, rather than mirroring one on its own, simply create a second
       ".png" or ".svg" graphics file with the same name, except with
       "_mirror" before the filename extension.

       For example, for the stamp "truck.png" you would create another file
       named "truck_mirror.png", which will be used when the stamp is
       mirrored (rather than using a backwards version of 'truck.png').

       As of Tux Paint 0.9.18, you may similarly provide a pre-flipped image
       with "_flip" in the name, and/or an image that is both mirrored and
       flipped, by naming it "_mirror_flip".

       Note: If the user flips and mirrors an image, and a pre-drawn
       "_mirror_flip" doesn't exist, but either "_flip" or "_mirror" does, it
       will be used, and mirrored or flipped, respectively.

     ----------------------------------------------------------------------

Fonts

     The fonts used by Tux Paint are TrueType Fonts (TTF).

     Simply place them in the "fonts" directory. Tux Paint will load the font
     and provide four different sizes in the 'Letters' selector when using
     the 'Text' tool.

     ----------------------------------------------------------------------

'Starters'

     'Starter' images appear in the 'New' dialog, along with solid color
     background choices. (Note: In earlier versions of Tux Paint, they
     appeared in the 'Open' dialog, together with saved drawings.)

     Unlike pictures drawn in Tux Paint by users and then opened later,
     opening a 'starter' creates a new drawing. When you save, the 'starter'
     image is not overwritten. Additionally, as you edit your new picture,
     the contents of the original 'starter' affect it.

     Coloring-Book Style

       The most basic kind of 'starter' is similar to a picture in a coloring
       book. It's an outline of a shape which you can then color in and add
       details to. In Tux Paint, as you draw, type text, or stamp stamps, the
       outline remains 'above' what you draw. You can erase the parts of the
       drawing you made, but you can't erase the outline.

       To create this kind of 'starter' image, simply draw an outlined
       picture in a paint program, make the rest of the graphic transparent
       (that will come out as white in Tux Paint), and save it as a PNG
       format file.

       Note: Previous to Tux Paint 0.9.21, images needed to be black and
       transparent. As of 0.9.21, if a Starter is black and white, with no
       transparency, white will be converted to transparent when the Starter
       is opened.

       Note: Previous to Tux Paint 0.9.22, Starters had to be in PNG or JPEG
       (backgrounds only) format. As of 0.9.22, they may be in SVG (vector
       graphics) or KPX (templates from Kid Pix, another childrens' drawing
       program; they are special files which simply contain a JPEG within).

     Scene-Style

       Along with the 'coloring-book' style overlay, you can also provide a
       separate background image as part of a 'starter' picture. The overlay
       acts the same: it can't be drawn over, erased, or affected by 'Magic'
       tools. However, the background can be!

       When the 'Eraser' tool is used on a picture based on this kind of
       'starter' image, rather than turning the canvas to a solid color, such
       as white, it returns that part of the canvas to the original
       background picture from the 'starter'.

       By creating both an overlay and a background, you can create a
       'starter' which simulates depth. Imagine a background that shows the
       ocean, and an overlay that's a picture of a reef. You can then draw
       (or stamp) fish in the picture. They'll appear in the ocean, but never
       'in front of' the reef.

       To create this kind of 'starter' picture, simply create an overlay
       (with transparency) as described above, and save it as a PNG. Then
       create another image (without transparency), and save it with the same
       filename, but with "-back" appended to the name. (e.g.,
       "reef-back.png" would be the background ocean picture that corresponds
       to the "reef.png" overlay, or foreground.)

     The 'starter' images should be the same size as Tux Paint's canvas. (See
     the "Loading Other Pictures into Tux Paint" section of README for
     details on sizing.) If they are not, they will be stretched, without
     affecting the shape ("aspect ratio"); however some smudging may be
     applied to the edges.

     Place them in the "starters" directory. When the 'New' dialog is
     accessed in Tux Paint, the 'starter' images will appear in the screen
     that appears, after the various solid color choices.

     Note: 'Starters' can't be saved over from within Tux Paint, since
     loading a 'starter' is really like creating a new image. (Instead of
     being blank, though there's already something there to work with.) The
     'Save' command simply creates a new picture, like it would if the 'New'
     command had been used.

     Note: 'Starters' are 'attached' to saved pictures, via a small text file
     that has the same name as the saved file, but with ".dat" as the
     extension. This allows the overlay and background, if any, to continue
     to affect the drawing even after Tux Paint has been quit, or another
     picture loaded or started. (In other words, if you base a drawing on a
     'starter' image, it will always be affected by it.)

     ----------------------------------------------------------------------

'Templates'

     'Template' images also appear in the 'New' dialog, along with solid
     color background choices and 'Starters'. (Note: Tux Paint prior to
     version 0.9.22 did not have the 'Template' feature.)

     Unlike pictures drawn in Tux Paint by users and then opened later,
     opening a 'template' creates a new drawing. When you save, the
     'template' image is not overwritten. Unlike 'starters', there is no
     immutable 'layer' above the canvas. You may draw over any part of it.

     When the 'Eraser' tool is used on a picture based on a 'template',
     rather than turning the canvas to a solid color, such as white, it
     returns that part of the canvas to the original picture from the
     'template'.

     'Templates' are simply image files (in PNG, JPG, SVG or KPX format). No
     preparation or conversion should be required.

     The 'template' images should be the same size as Tux Paint's canvas.
     (See the "Loading Other Pictures into Tux Paint" section of README for
     details on sizing.) If they are not, they will be stretched, without
     affecting the shape ("aspect ratio"); however some smudging may be
     applied to the edges.

     Place them in the "templates" directory. When the 'New' dialog is
     accessed in Tux Paint, the 'template' images will appear in the screen
     that appears, after the various solid color choices and 'starters'.

     Note: 'Templates' can't be saved over from within Tux Paint, since
     loading a 'template' is really like creating a new image. (Instead of
     being blank, though there's already something there to work with.) The
     'Save' command simply creates a new picture, like it would if the 'New'
     command had been used.

     Note: 'Templates' are 'attached' to saved pictures, via a small text
     file that has the same name as the saved file, but with ".dat" as the
     extension. This allows the background to continue to be available to the
     drawing (e.g., when using the 'Eraser' tool) even after Tux Paint has
     been quit, or another picture loaded or started. (In other words, if you
     base a drawing on a 'template' image, it will always be affected by it.)

     ----------------------------------------------------------------------

Translations

     Tux Paint supports numerous languages, thanks to use of the "gettext"
     localization library. (See OPTIONS for how to change locales in
     Tux Paint.)

     To translate Tux Paint to a new language, copy the translation template
     file, "tuxpaint.pot" (found in Tux Paint's source code, in the folder
     "src/po/"). Rename the copy as a ".po" file, with an appropriate name
     for the locale you're translating to (e.g., "es.po" for Spanish; or
     "pt_BR.po" for Brazilian Portuguese, versus "pt.po" or "pt_PT.po" for
     Portuguese spoken in Portugal.)

     Open the newly-created ".po" file - you can edit in a plain text edtior,
     such as Emacs, Pico or VI on Linux, or NotePad on Windows. The original
     English text used in Tux Paint is listed in lines starting with "msgid".
     Enter your translations of each of these pieces of text in the empty
     "msgstr" lines directly below the corresponding "msgid" lines. (Note: Do
     not remove the quotes.)

     Example:

       msgid "Smudge"
       msgstr "Manchar"
        
       msgid "Click and move to draw large bricks."
       msgstr "Haz clic y arrastra para dibujar ladrillos grandes."

     A graphical tool, called poEdit (http://www.poedit.net/), is available
     for Linux, Windows and Mac OS X.

     Note: It is best to always work off of the latest Tux Paint text catalog
     template ("tuxpaint.pot"), since new text is added, and old text is
     occasionally changed. The text catalog for the upcoming, unreleased
     version of Tux Paint can be found in Tux Paint's CVS repository (see:
     http://www.tuxpaint.org/download/source/cvs/), and on the Tux Paint
     website at http://www.tuxpaint.org/help/po/.

     To edit an existing translation, download the latest ".po" file for that
     language, and edit it as described above.

     You may send new or edited translation files to Bill Kendrick, lead
     developer of Tux Paint, at: bill@newbreedsoftware.com, or post them to
     the "tuxpaint-i18n" mailing list (see: http://www.tuxpaint.org/lists/).

     Alternatively, if you have an account with SourceForge.net, you can
     request to be added to the "tuxpaint" project and receive write-access
     to the CVS source code repository so that you may commit your changes
     directly.

     Note: Additional locale support also requires additions to Tux Paint's
     source code (/src/i18n.h and /src/i18n.c), and requires updates to the
     Makefile, to have the ".po" gettext catalog source files compiled into
     ".mo" files, and installed, for use at runtime.

Alternative Input Methods

     As of version 0.9.17, Tux Paint's "Text" tool can provide alternative
     input methods for some languages. For example, when Tux Paint is running
     with a Japanese locale, the right [Alt] key can be pressed to cycle
     between Latin, Romanized Hiragana and Romanized Katakana modes. This
     allows native characters and words to be entered into the "Text" tool by
     typing one or more keys on a keyboard with Latin characters (e.g., a
     US QWERTY keyboard).

     To create an input method for a new locale, create a text file with a
     name based on the locale (e.g., "ja" for Japanese), with ".im" as the
     extension (e.g., "ja.im").

     The ".im" file can have multiple character mapping sections for
     different character mapping modes. For example, on a Japanese typing
     system, typing [K] [A] in Hiragana mode generates a different Unicode
     character than typing [K] [A] in Katakana mode.

     List the character mappings in this file, one per line. Each line should
     contain (separated by whitespace):

       * the Unicode value of the character, in hexadecimal (more than one
         character can be listed, separated by a colon (':'), this allowing
         some sequences to map to words)
       * the keycode sequence (the ASCII characters that must be entered to
         generate the Unicode character)
       * a flag (or "-")

     Start additional character mapping sections with a line containign the
     word "section".

     Example:

       # Hiragana
       304B   ka   -
       304C   ga   -
       304D   ki   -
       304E   gi   -
       304D:3083   kya   -
       3063:305F   tta   -
        
       # Katakana
       section
       30AB   ka   -
       30AC   ga   -
       30AD   ki   -
       30AE   gi   -

     Note: Blank lines within the ".im" file will be ignored, as will any
     text following a "#" (pound/hash) character - it can be used to denote
     comments, as seen in the example above.

     Note: Meanings of the flags are locale-specific, and are processed by
     the language-specific source code in "src/im.c". For example, "b" is
     used in Korean to handle Batchim, which may carry over to the next
     character.

     Note: Additional input method support also requires additions to
     Tux Paint's source code (/src/im.c), and requires updates to the
     Makefile, to have the ".im" files installed, for use at runtime.