to_if_held_down

to_if_held_down posts events when the from key is held down.

Example

The following json changes the escape key to open Launchpad when the escape key is held down.

💡 How to use this example 
{
    "description": "Open Launchpad when escape is held down",
    "manipulators": [
        {
            "type": "basic",
            "from": {
                "key_code": "escape",
                "modifiers": { "optional": ["caps_lock"] }
            },
            "to_if_alone": [{ "key_code": "escape" }],
            "to_if_held_down": [
                { "apple_vendor_keyboard_key_code": "launchpad" }
            ],
            "parameters": {
                "basic.to_if_alone_timeout_milliseconds": 250,
                "basic.to_if_held_down_threshold_milliseconds": 250
            }
        }
    ]
}

Parameter

You can adjust the threshold of holding down periods by parameters > basic.to_if_held_down_threshold_milliseconds like the above example.

More advanced example

The nature of to_if_held_down means that events may not fire in the order the keys are pressed when typing in combination with other keys. (Even if the to_if_held_down key is pressed first, its event will fire after the others.)

In cases where this behavior becomes problematic, such as wanting to modify a letter key to another key only when held down, a more advanced configuration will be necessary.

In the example below, the f key becomes the left shift key when held down.

In this example, to_if_held_down.to_if_canceled is used to send the f key event when the next key is pressed. Additionally, to_if_alone is used to send the f key when it is pressed alone.

The halt specified in to_if_alone prevents the f key from being sent by both to_if_alone and to_delayed_action.

💡 How to use this example 
{
    "description": "Change the f key to the left shift key if held down",
    "manipulators": [
        {
            "type": "basic",
            "from": {
                "key_code": "f",
                "modifiers": { "optional": ["any"] }
            },
            "to_if_alone": [
                {
                    "key_code": "f",
                    "halt": true
                }
            ],
            "to_if_held_down": [{ "key_code": "left_shift" }],
            "to_delayed_action": {
                "to_if_canceled": [{ "key_code": "f" }]
            },
            "parameters": {
                "basic.to_delayed_action_delay_milliseconds": 500,
                "basic.to_if_held_down_threshold_milliseconds": 500
            }
        }
    ]
}