* 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 letter.
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
* Two consecutive newlines mark beginning of a new row
* 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`
*`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.
*`codePoints`: when multiple code points should be entered, only available for `multi_text_key`
*`label`: text to display on the key, determined from code if empty
* There are some special values, see the [label section](#labels)
*`groupId`: which additional popup keys to show, `0` is default and does not add anything, `1` adds the comma popup keys, and `2` adds the period popup keys
*`popup`: list of keys to add in the popup, e.g. `"label": ")", "popup": {"relevant": [{ "label": "." }]}` is a `)` key with a `.` popup
* Note that in popup keys, properties are ignored with the exception of `$`, `code`, `codePoints`, and `label`
* When specifying a _selector_ key class in a popup key, it will be evaluated correctly (e.g. for changing popups dependent on shift state)
*`width`: width of the key in units of screen width, e.g. a key with `"width": 0.1` has a width of 10% of the screen, defaults to `0`
* A special value is `-1`, which means the key expands to the available space not already used by other keys (e.g. the space bar)
* If the sum of widths in a row is greater than 1, keys are rescaled to fit on the screen
*`labelFlags`: allows specific effects, see [here](app/src/main/res/values/attrs.xml) in the section _keyLabelFlags_ for names and numeric values
## Labels
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)
* _symbol_alpha_: toggle alpha / symbol keyboard
* _numpad_: switch to numpad layout
* _emoji_: switch to emoji view
* _com_: display common TLDs (.com and similar, currently not localized)
* _language_switch_: language switch key
* _action_: the action (enter) key
* _delete_: delete key
* _shift_: shift key, will change label when in symbols layout
* _period_: `.` key with punctuation popups, will adapt to language-specific period
* _comma_: `,` key with special popups, will adapt to language-specific comma, or display `/` in URL fields and `@` in email fields
* _space_: space key, with icon when using a number layout
* _zwnj_: Zero-width non-joiner (automatically added next to space in alphabet layout for some languages)
* If you want different key label and use text, set the label to [label]|[text], e.g. `aa|bb` will show `aa`, but pressing the key will input `bb`.
You can also specify special key codes like `a|!code/key_action_previous`, 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.
It's also possible to specify an icon together with a code `!icon/previous_key|!code/key_action_previous`, but this is not fully supported yet.
* 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)
