* the _simple_ format is a text file with one key label per line, and two consecutive line breaks indicating a switch to the next row, [example](app/src/main/assets/layouts/qwerty.txt)
* the _json_ format taken from [FlorisBoard](https://github.com/florisboard/florisboard/blob/master/CONTRIBUTING.md#adding-the-layout), but only "normal" keys are supported (i.e. no action keys and similar), [example](app/src/main/assets/layouts/azerty.json)
Adding too many keys or too long texts will make the keyboard look awkward or broken, and even crash the app under some specific conditions (popup keys are especially prone for this).
If you use an external glide typing library, you likely will have issues if your layout contains duplicate keys, or keys with text longer than a single character.
If the layout has exactly 2 keys in the bottom row, these keys will replace comma and period keys. More exactly: the first key will replace the first functional key with `"groupId": 1` in the bottom row, and the second key with replace the first key with `"groupId": 2`.
* Key format: [label] [popup keys], all separated by space, e.g. `a 0 + *` will create a key with text `a`, and the keys `0`, `+`, and `*` on long press
* Normal json layout with [lenient](https://kotlinlang.org/api/kotlinx.serialization/kotlinx-serialization-json/kotlinx.serialization.json/-json-builder/is-lenient.html) parsing, and ignoring lines starting with `//`.
* For anything else than small changes and copy/pasting text the in-app editor is unsuitable. A proper text editor (e.g. Kate or Notepad++) can significantly simplify work on json files.
* There is no need for specifying a `code`, it will be determined from the label automatically
* You can still specify it, but it's only necessary if you want key label and code to be different (please avoid contributing layout with unnecessary codes to HeliBoard)
* Key classes: specified with `$`, usually you can omit them in HeliBoard
*`text_key`: normal key, default
*`auto_text_key`: used in FlorisBoard for a key that changes text case when shift is enabled, HeliBoard does that anyway unless disabled with a _labelFlag_
*`multi_text_key`: key with an array of code points, e.g. `{ "$": "multi_text_key", "codePoints": [2509, 2480], "label": "্র" }`
* there are also selector classes, which allow to change keys conditionally, see the [dvorak layout](https://github.com/Helium314/HeliBoard/blob/main/app/src/main/assets/layouts/dvorak.json) for an example:
*`case_selector`: keys for `lower` and `upper` (both mandatory), similar to `shift_state_selector`
* the `<emoji/language>KeyEnabled` keys will be used if the corresponding setting is enabled, `symbols`, `moreSymbols`, `alphabet` will be used when the said keyboard view is active
*`code`: code point that is entered when the key is pressed, determined from the label by default, not available for `multi_text_key`
* There are special negative values available, e.g. the ones used by functional keys, see [KeyCode.kt](/app/src/main/java/helium314/keyboard/keyboard/internal/keyboard_parser/floris/KeyCode.kt). There are several not yet supported key codes in there, you can see in the function `checkAndConvertCode` which ones are working.
*`groupId`: which additional popup keys to show, `0` is default and does not add anything, `1` adds the comma popup keys, `2` adds the period popup keys, `3` adds the action key popup keys (looks awkward though), `-1` suppresses additional popups based on the label
*`labelFlags`: allows specific effects, see [here](app/src/main/res/values/attrs.xml#L251-L287) in the section _keyLabelFlags_ for names and numeric values
* Since json does not support hexadecimal-values, you have to use the decimal values in the comments in the same line.
* In case you want to apply multiple flags, you will need to combine them using [bitwise OR](https://en.wikipedia.org/wiki/Bitwise_operation#OR). In most cases this means you can just add the individual values, only exceptions are `fontDefault`, `followKeyLabelRatio`, `followKeyHintLabelRatio`, and `autoScale`.
In the simple format you only specify labels, in json layouts you do it explicitly via the `label` property.
Usually the label is what is displayed on the key. However, there are some special labels:
* Currency keys
*`$$$` will be replaced by the local currency, depending on your current layout language. If you define a key with `$$$` without defining popup keys, it will get the first 4 additional currencies (see below) as popup
*`$$$1` - `$$$5` will be replaced by currencies available on long-pressing the currency key
* Functional keys (incomplete list)
* _alpha_: switch to alphabet keyboard (or main phone keyboard in case of phone layout)
* _symbol_: switch to symbol keyboard (or phone symbols keyboard in case of phone layout)
* See [KeyLabel.kt](app/src/main/java/helium314/keyboard/keyboard/internal/keyboard_parser/floris/KeyLabel.kt) for more available labels that are parsed to the corresponding key.
* In case a label clashes with text you want to add, put a `\` in front of the text you want, e.g. `\space` will write the label `space` instead of adding a space bar.
* Note that you need to escape the `\` in json files by adding a second `\`.
You can also specify special key codes like `a|!code/key_action_previous` or `abc|!code/-10043`, but it's cleaner to use a json layout and specify the code explicitly. Note that when specifying a code in the label, and a code in a json layout, the code in the label will be ignored.
* You can find available icon names in [KeyboardIconsSet](/app/src/main/java/helium314/keyboard/keyboard/internal/KeyboardIconsSet.kt). You can also use toolbar key icons using the uppercase name of the [toolbar key](/app/src/main/java/helium314/keyboard/latin/utils/ToolbarUtils.kt#L109), e.g. `!icon/redo`
* If you add a layout to an existing language, add a string with the layout name to use instead of `subtype_generic`. The new string should be added to default [`strings.xml`](/app/src/main/res/values/strings.xml), and optionally to other languages. `%s` will be replaced with the language.
*`[labels]` may contain non-default labels for the following keys `symbol`, `alphabet`, `shift_symbol`, `shift_symbol_tablet`, `comma`, `period`, `question`
*`[number_row]` may contain a custom number row (1-9 and 0 separated by space). You should also add the language to `numberRowLocales` in [`PreferencesSettingsFragment`](app/src/main/java/helium314/keyboard/latin/settings/PreferencesSettingsFragment.java) so the user can opt into having a localized number row.
*`[extra_keys]` are typically keys shown in the default layout of the language. This is currently only used for latin layouts to avoid duplicating layouts for just adding few keys on the right side. The layout name need to end with `+`, but the `+` is removed when looking up the actual layout.
* If you add a new language for which Android does not have a display name, it will be displayed using the language tag
* Avoiding this currently is more complicated than necessary: add the language tag to [LocaleUtils.getLocaleDisplayNameInSystemLocale](/app/src/main/java/helium314/keyboard/latin/common/LocaleUtils.kt#L181) to have an exception, and add a string named `subtype_<langage tag, but with _ instead of ->` to [`strings.xml`](/app/src/main/res/values/strings.xml). Further you may need to add a `subtype_in_root_locale_<language tag>` to [donottranslate.xml](/app/src/main/res/values/donottranslate.xml), and add the language tag to `subtype_locale_exception_keys` and `subtype_locale_displayed_in_root_locale`.
* If a newly added language does not use latin script, please update the default scripts method `Locale.script` in [ScriptUtils](app/src/main/java/helium314/keyboard/latin/utils/ScriptUtils.kt)
Customizing functional keys mostly works like other layouts, with some specific adjustments:
* When using the default functional layout, emoji, language switch and numpad keys are actually always in the layout, but get removed depending on settings and the main layout (alphabet, symbols or more symbols). This removal is disabled when you customize any functional layout, so to not block you from adding e.g. a numpad key in alphabet layout.
* When you use a language that has a ZWNJ key, the key will automatically be added to the right of the (first) space bar in the bottom row
* Adding popups to keys that switch layout does not work properly, as usually the layout is switched as soon as the key gets pressed.
* separating top and bottom rows in case you want to have functional key rows aligned to the top of the keyboard (add a row with the placeholder as the only key)
* if the last row in functional keys does not contain a placeholder, it is used as bottom row (like in the default functional layout)
* When you functional keys only for some of alphabet, symbols and more symbols, behavior is as follows
* more symbols will fall back to symbols, then normal
* symbols will fall back to normal, then default (if you only customized more symbols functional layout)
* normal will fall back to default (if you only customized symbols and/or more symbols functional layout)
