core/dev.fritz2.core/Shortcut

Shortcut

data class Shortcut(val key: String, val ctrl: Boolean = false, val alt: Boolean = false, val shift: Boolean = false, val meta: Boolean = false) : ModifierShortcut

Shortcut represents a grouping type upon the "key" and the modifier key properties of a KeyboardEvent. More info here

A shortcut can be easily constructed by a KeyboardEvent which makes this abstraction so feasible to use with the keyboard event handling like:

div {
    // raw usage (prefer next example!)
    keydowns.map { Shortcut(it) } handledBy { /* use object for further processing */}

    // use factory function to create a Shortcut object
    keydowns.map { shortcutOf(it) } handledBy { /* use object for further processing */}

    // combine with `filter` functions is a common pattern:
    keydowns.filter { shortcutOf(it) == Keys.Control + "k") handledBy {
        // only if combination was pressed and with access to the original event too!
        // all other key events will be ignored
    }
}

This class enables by its implementation of ModifierShortcut the concatenation with other modifiers, but it prevents the meaningless combination of shortcuts:

// this works:
Shortcut("F") + Keys.Alt + Keys.Shift
// this won't work:
Shortcut("F") + Shortcut("P")

// Ths first example could also be constructed by an appropriate constructor call:
Shortcut("F", alt = true, shift = true)

Be aware that the Shortcut.key property is case sensitive just likte the KeyboardEvent.key property. So in order to match a shortcut with a capital key of an event, you must the Shortcut.shift flag to true.

// A capital "K" should be matched, but would fail here:
keydowns.map { shortcutOf(it) == Shortcut("K") } // would emit `false`!
// Instead this will work:
keydowns.map { shortcutOf(it) == Shortcut("K", shift = true) }
// or with this operator an better readbility:
keydowns.map { shortcutOf(it) == Keys.Shift + "K" }

On the other hand there will be no matching for a lowercase key with shift property set to true either!