# Technical reference

&ktuberling; offers a gentle and rewarding introduction to &kde; customization and programming. The application can be extended. For example, without any coding, new playgrounds can be added by changing the graphics files. By adding appropriate sound files, translators can change the sounds to their native tongue!

If you extend or add to the game please consider sending your additions to the developer Eric Bischoff for inclusion in future releases.

## For artists

The size and shape of the playground and the number of objects can be changed. New playgrounds can be added. Only two image files need to be created for each playground: a gameboard and a mask. A maximum of 8 playgrounds is allowed, out of which only 3 are currently used.

Six images are used in &ktuberling;: `potato-game.png`, `potato-mask.png`, `penguin-game.png`, `penguin-mask.png`, `aquarium-game.png` and `aquarium-mask.png`. The standard location for these files is the directory `$KDEDIR/share/apps/ktuberling/pics/`.

The first type of images, `*-game.png` holds the playground and the objects that the user selects. This is the graphic that the user sees when playing the game.

The second type of images, `*-mask.png`, contains only masks of the objects. The masks are used to delimit the borders of the objects and, in some cases, give the object some transparancy (for example, the spectacles). It is mandatory to put the objects at the same position in the gameboard file as in the mask file.

In the same directory, a file named `layout.xml`. (`$KDEDIR/share/apps/ktuberling/pics/layout.xml`) tells which images to use and links them to menu entries. It also contains the position parameters of the playground and the objects in the gameboard and in the masks. It assigns the sounds to objects and places the objects in groups. It finally declares languages as sets of translated sounds. It follows standard XML syntax (see details below).

Still in the same directory, a file named `layout.i18n` (`$KDEDIR/share/apps/ktuberling/pics/layout.xml`) recapitulates the strings in `layout.xml` that can be translated:

- The menu entries that allow to choose the playground and the language

- The names of the categories of objects

One directory above, a file named `ktuberlingui.rc` (`$KDEDIR/share/apps/ktuberling/ktuberlingui.rc`) is a second XML file describing the menus of &ktuberling;. It should contain one `<action>` tag per playground and language. The symbolic name of the action in this file should be identical to the symbolic name of the action in `layout.xml`.

## Translation

Besides the usual `.po` files mechanism for translating program labels and prompts, the sounds can be localized too.

If the various translators can record their voice to a `.wav` file, they can store that file to the language-specific subdirectory of the sounds directory. The name of the sound is then assigned to a file in the `layout.xml` file. For example, if destination language is Italian, translators can record their voice in `.wav` files located in `$KDEDIR/share/apps/ktuberling/sounds/it`. Then they can assign the sound named hat to the filename `it/cappello.wav`.

In a future release, &ktuberling; will use OGG Vorbis rc3 file format for sounds. At that moment, it will be possible to convert the WAV files to OGG Vorbis rc3 through the following command line:

    $ oggenc_rc3 -o sound.ogg sound.wav

Information on how to work with the translation mechanisms in &kde; is available in The KDE Translation HOWTO.

## For programmers

&ktuberling; isn't really difficult to extend for programmers.

### C++ classes

`TopLevel`

- Top-level window and basic program management

`PlayGround`

- Description of one of the game levels

`ToDraw`

- Description of one of the graphical objects to be drawn

`SoundFactory`

- Description of one of the languages and its sounds

`Action`

- One of the user's manipulation in the undo/redo stack

### `.tuberling` files structure

A `.tuberling` file holds all the necessary data to redraw a tuberling. It can be edited with an ordinary text editor.

The first line holds the number of the playground.

On all other lines, there is one graphical object per line, in the order that is used to draw them. Each line contains 5 numbers: the identifier of the object, and the rectangle where it should be drawn (left, top, right, bottom). The numbers are separated by whitespaces.

## Structure of the layout file (`layout.xml`)

The top-level tag is unique and is named `<ktuberling>`. It contains several `<playground>` tags, one per playground, and several `<language>` tags, one per language.

The `<playground>` tag has two attributes: `gameboard` and `masks`. These attributes give the name of the files holding the pictures. The `<playground>` tag also contains one `<menuitem>` tag, one `<editablearea>` tag, several `<category>` tags, and several `<object>` tags.

The `<menuitem>` tag describes the action identifier of the menu item allowing to select position of the area where you can drop objects, and the label of this menu item. This action identifier should be identical to the one in `ktuberlingui.rc`.

The `<editablearea>` tag describes the position of the area where you can drop objects, and the name of the sound associated with it.

The `<category>` tag describes the position and the label of a text describing a group of objects. For example, it can describe the position and the text of the group of goodies.

The `<object>` tag describes the position (in the gameboard and in the masks) of an object, as well as the name of the sound associated with it.

The `<language>` tag has one attribute: `code` This attribute give the code of the locale for that language. The `<language>` tag also contains one `<menuitem>` tag and several `<sound>` tags.

The lower level tags are not explained here, since their meaning is quite straightforward. If you modify `layout.xml`, don't forget to modify `layout.i18n` and `ktuberlingui.rc` accordingly.