keyman-touch-layout files

Used by: : Keyman Developer.

Description: : A .keyman-touch-layout file is a JSON format file that describes a keyboard layout for touch devices.

Details: : Referenced by a Keyman keyboard (.KMN) and compiles into the target keyboard .js file.

Distributed with keyboard: : This is a keyboard development file and should not be distributed with your package.

Sample JSON

This cut-down sample shows just a single key, with the key cap "ឆ", and a single longpress key under it with the key cap "ឈ".

{
  "phone": {
    "displayUnderlying": false,
    "font": "Khmer Busra Kbd",
    "fontsize": "0.8em",
    "layer": [ {
      "id": "default",
      "row": [ {
        "id": 1,
        "key": [ {
          "id": "K_Q", "text": "ឆ",
          "sk": [ { "text": "ឈ", "id": "K_Q", "layer": "shift" } ]
        } ]
      } ]
    } ]
  }
}

Key properties

For each visual key, the appearance and behaviour is determined by a number of properties:

Key code

Each key must be given an identifying key code which is unique to the key layer. Key codes by and large correspond to the virtual key codes used when creating a keyboard program for a desktop keyboard, and should start with K_, for keys mapped to standard Keyman virtual key names, e.g. K_HYPHEN, and T_ or U_ for user-defined names, e.g. T_ZZZ. If keyboard rules exist matching the key code in context, then the output from the key will be determined by the processing of those rules. It is usually best to include explicit rules to manage the output from each key, but if no rules matching the key code are included in the keyboard program, and the key code matches the pattern U_xxxx[_yyyy...] (where xxxx and yyyy are 4 to 6-digit hex strings), then the Unicode characters U+xxxx and U+yyyy will be output. As of Keyman 15, you can use more than one Unicode character value in the id (earlier versions permitted only one). The key code is always required, and a default code will usually be generated automatically by Keyman Developer.

• K_xxxx is used for a standard Keyman Desktop key name, e.g. K_W, K_ENTER. You cannot make up your own K_xxxx names. Many of the K_ ids have overloaded output behaviour, for instance, if no rule is matched for K_W, Keyman will output 'w' when it is touched. The standard key names are listed in Virtual Keys and Virtual Character Keys. Typically, you would use only the "common" virtual key codes.

• T_xxxx is used for any user defined names, e.g. T_SCHWA. If you wanted to use it, T_ENTER would also be valid. If no rule matches it, the key will have no output behaviour.

• U_####[_####] is used as a shortcut for a key that will output those Unicode values, if no rule matches it. This is similar to the overloaded behaviour for K_ ids. Thus #### must be valid Unicode characters. E.g. U_0259 would generate a schwa if no rule matches. It is still valid to have a rule such as + [U_0259] > ...

As noted above, some K_xxxx codes emit characters, if no rule is defined. There are also some codes which have special functions:

Any key can be used to switch keyboard layers (see nextlayer), but the following layer-switching key codes have been added for switching to some commonly used secondary layers. Note that these keys have no specific meaning; you must still set the nextlayer property on the key.

Key text

The key text is simply the character (or characters) that you want to appear on the key cap. This will usually be the same as the characters generated when the key is touched, unless contextual rules are used to generate output according to a multi-key sequence, as will be true for the GFF Amharic keyboard. Unicode characters can be specified either as a string using a target font or using the standard hex notation \uxxxx. This may be sometimes more convenient, for example, for characters from an uninstalled font, or for diacritic characters that do not render well alone.

A number of special text labels are recognized as identifying special purpose keys, such as Shift, Backspace, Enter, etc., for which icons are more appropriately used than a text label. A special font including these icons is included with Keyman and automatically embedded and used in any web page using Keyman. The list of icons in the font will probably be extended in future, but for now the following special labels are recognized:

The following additional symbols are also available, but intended for working with legacy desktop layouts, and not recommended for general use:

Key type

The general appearance of each key is determined by the key type, which is selected (in Keyman Developer) from a drop-down list. While generally behavior is not impacted by the key type, Spacer keys cannot be selected.

The colour, shading and borders of each key type is actually set by a style sheet which can be customized by the page developer.

font-family

If a different font is required for a particular key text, the font-family name can be specified. The font used to display icons for the special keys (as mentioned above) does not need to be specified, as it will be automatically applied to a key that uses any of the special key text labels.

font-size

If a particular key cap text requires a different font size from the default for the layout, it should be specified in em units. This can be helpful if a the key text is either an unusually large character or, alternatively, a word or string of several characters that would not normally fit on the key.

width

The layout is scaled to fit the widest row of keys in the device width, assuming a default key width of 100 units. Keys that are to be wider or narrower than the default width should have width specified as a percentage of the default width. For any key row that is narrower than the widest row, the width of the last key in the row will be automatically increased to align the right hand side of the key with the key with the right edge of the keyboard. However, where this is not wanted, a "spacer" key can be inserted to leave a visible space instead. As shown in the above layouts, where the spacer key appears on the designer screen as a narrow key, but will not be visible in actual use.

pad

Padding to the left of each key can be adjusted, and specified as a percentage of the default key width. If not specified, a standard padding of 5% of the key width is used between adjacent keys.

layer

To simplify correspondence with desktop keyboards and avoid the need for using a separate keyboard mapping program, touch layout keys can specify a desktop keyboard layer that the keystroke should be interpreted as coming from. Layer names of shift, ctrl, alt, ctrlshift, altshift, ctrlalt and ctrlaltshift can be used to simulate use of the appropriate modifier keys when processing rules.

nextlayer

The virtual keys K_SHIFT, K_CONTROL, K_MENU, etc. are normally used to switch to another key layer, which is implied by the key code. The left and right variants of those key codes, and also additional layer-switching keys mentioned above (K_NUMERALS, K_SYMBOLS, K_CURRENCIES, K_ALTGR) can also be used to automatically switch to the appropriate key layer instead of outputting a character. However, it is sometimes useful for a key to output a character first, then switch to a new layer, for example, switching back to the default keyboard layer after a punctuation key on a secondary layer had been used. Specifying the nextlayer for a key allows a different key layer to be selected automatically following the output of the key. Of course, that can be manually overridden by switching to a different layer if preferred.

Another way the nextlayer property can be used is for a non-standard layer switching key. So, for example, for the GFF Amharic keyboard phone layout, switching back to the base layer uses a T_ALPHA key code, in which nextlayer is set as default. In this case, it is also necessary to add a rule to the keyboard program:

+ [T_ALPHA] > nul

to ensure that the key's scan code is ignored by the keyboard mapping.

When a key in a touch layout definition includes a Next Layer control, this takes precedence over setting layer via the layer store (as the Next Layer control is applied once the rule has finished processing).

subkey

Arrays of longpress 'subkeys' or pop-up keys can be defined for any key, and will appear momentarily after the key is touched if not immediately released. This provides a major advantage over physical desktop keyboards in that many more keys can be made available from a single layer, without cluttering up the basic appearance of the layout. For the GFF Amharic keyboard, we have already noted how such subkey arrays are used to manage the extra keys that, on the desktop keyboard, would appear in the shift layer. But they are also used to provide another way to enter the two different types of each syllable-initial vowels (glottal or pharyngeal), as a visual alternative to pressing the key twice.

The same properties that are defined for standard keys can also be specified for each subkey except that the width of each key in a subkey array will always be the same as the width of the key that causes the subkeys to be shown, and key spacing always uses the default padding value.

The GFF Amharic keyboard, like many others, is mnemonic, so it is useful to also display the standard key cap letter that would appear on the key of a desktop keyboard. This is enabled globally in the On-Screen layout editor and applies to both the On-Screen keyboard and touch layouts.

JSON Schema

{
  "$schema": "http://json-schema.org/schema#",
  "$ref": "#/definitions/touch-layout",
  "$comment": "Version: 16.0",
  "description": "A Keyman Touch Layout file, per version 16.0, clean spec, no legacy data or types",

  "definitions": {
    "touch-layout": {
      "type": "object",
      "properties": {
        "tablet": { "$ref": "#/definitions/platform" },
        "phone": { "$ref": "#/definitions/platform" },
        "desktop": { "$ref": "#/definitions/platform" }
      },
      "minProperties": 1,
      "additionalProperties": false
    },

    "platform": {
      "type": "object",
      "properties": {
        "font": { "$ref": "#/definitions/font-spec" },
        "fontsize": { "$ref": "#/definitions/fontsize-spec" },
        "layer": { "$ref": "#/definitions/layers" },
        "displayUnderlying": { "type": "boolean" },
        "defaultHint": { "type": "string", "enum": ["none","dot","longpress","multitap","flick","flick-n","flick-ne","flick-e","flick-se","flick-s","flick-sw","flick-w","flick-nw"] }
      },
      "required": ["layer"],
      "additionalProperties": false
    },

    "layers": {
      "type": "array",
      "items": { "$ref": "#/definitions/layer" },
      "minItems": 1
    },

    "layer": {
      "type": "object",
      "properties": {
        "id": { "$ref": "#/definitions/layer-id" },
        "row": { "$ref": "#/definitions/rows" }
      },
      "required": ["id", "row"],
      "additionalProperties": false
    },

    "layer-id": {
      "type": "string",
      "pattern": "^[a-zA-Z0-9_-]+$"
    },

    "rows": {
      "type": "array",
      "items": { "$ref": "#/definitions/row" },
      "minItems": 1
    },

    "row": {
      "type": "object",
      "properties": {
        "id": { "$ref": "#/definitions/row-id" },
        "key": { "$ref": "#/definitions/keys" }
      },
      "required": ["id", "key"],
      "additionalProperties": false
    },

    "row-id": {
      "type": "integer",
      "minimum": 0,
      "maximum": 100
    },

    "keys": {
      "type": "array",
      "items": { "$ref": "#/definitions/key" },
      "minItems": 1
    },

    "key": {
      "type": "object",
      "properties": {
        "id": { "$ref": "#/definitions/key-id" },
        "text": { "type": "string" },
        "layer": { "$ref": "#/definitions/layer-id" },
        "nextlayer": { "$ref": "#/definitions/layer-id" },
        "font": { "$ref": "#/definitions/font-spec" },
        "fontsize": { "$ref": "#/definitions/fontsize-spec" },
        "sp": { "$ref": "#/definitions/key-sp" },
        "pad": { "$ref" : "#/definitions/key-pad" },
        "width": { "$ref" : "#/definitions/key-width" },
        "sk": { "$ref": "#/definitions/subkeys" },
        "flick": { "$ref": "#/definitions/flick" },
        "multitap": { "$ref": "#/definitions/subkeys" },
        "hint": { "type": "string" }
      },
      "anyOf": [
        {"required": ["id"]},
        {"required": ["sp"]},
        {"required": ["sk"]},
        {"required": ["flick"]},
        {"required": ["multitap"]}
      ],
      "additionalProperties": false
    },

    "key-id": {
      "type": "string",
      "pattern": "^[TKUtku]_[a-zA-Z0-9_]+$"
    },

    "key-sp": {
      "type": "integer",
      "enum": [0, 1, 2, 8, 9, 10]
    },

    "key-pad": {
      "type": "number",
      "minimum": 0,
      "maximum": 100000
    },

    "key-width": {
      "type": "number",
      "minimum": 0,
      "maximum": 100000
    },

    "subkeys": {
      "type": "array",
      "items": { "$ref": "#/definitions/subkey" },
      "minItems": 1
    },

    "subkey": {
      "type": "object",
      "properties": {
        "id": { "$ref": "#/definitions/key-id" },
        "text": { "type": "string" },
        "layer": { "$ref": "#/definitions/layer-id" },
        "nextlayer": { "$ref": "#/definitions/layer-id" },
        "font": { "$ref": "#/definitions/font-spec" },
        "fontsize": { "$ref": "#/definitions/fontsize-spec" },
        "sp": { "$ref": "#/definitions/key-sp" },
        "pad": { "$ref" : "#/definitions/key-pad" },
        "width": { "$ref" : "#/definitions/key-width" }
      },
      "required": ["id"],
      "additionalProperties": false
    },

    "flick": {
      "type": "object",
      "patternProperties": {
        "^(n|s|e|w|ne|nw|se|sw)$": { "$ref": "#/definitions/subkey" }
      },
      "minProperties": 1,
      "additionalProperties": false
    },

    "font-spec": {
      "type": "string"
    },

    "fontsize-spec": {
      "type": "string"
    }
  }
}