SingleActivator constructor Null safety

const SingleActivator(
  1. LogicalKeyboardKey trigger,
  2. {bool control = false,
  3. bool shift = false,
  4. bool alt = false,
  5. bool meta = false,
  6. bool includeRepeats = true}
)

Triggered when the trigger key is pressed while the modifiers are held.

The trigger should be the non-modifier key that is pressed after all the modifiers, such as LogicalKeyboardKey.keyC as in Ctrl+C. It must not be a modifier key (sided or unsided).

The control, shift, alt, and meta flags represent whether the respect modifier keys should be held (true) or released (false). They default to false.

By default, the activator is checked on all RawKeyDownEvent events for the trigger key. If includeRepeats is false, only the trigger key events with a false RawKeyDownEvent.repeat attribute will be considered.

link
In the following example, the shortcut Control + C increases the counter:
To create a local project with this code sample, run:
flutter create --sample=widgets.SingleActivator.SingleActivator.1 mysample

Implementation

const SingleActivator(
  this.trigger, {
  this.control = false,
  this.shift = false,
  this.alt = false,
  this.meta = false,
  this.includeRepeats = true,
}) : // The enumerated check with `identical` is cumbersome but the only way
     // since const constructors can not call functions such as `==` or
     // `Set.contains`. Checking with `identical` might not work when the
     // key object is created from ID, but it covers common cases.
     assert(
       !identical(trigger, LogicalKeyboardKey.control) &&
       !identical(trigger, LogicalKeyboardKey.controlLeft) &&
       !identical(trigger, LogicalKeyboardKey.controlRight) &&
       !identical(trigger, LogicalKeyboardKey.shift) &&
       !identical(trigger, LogicalKeyboardKey.shiftLeft) &&
       !identical(trigger, LogicalKeyboardKey.shiftRight) &&
       !identical(trigger, LogicalKeyboardKey.alt) &&
       !identical(trigger, LogicalKeyboardKey.altLeft) &&
       !identical(trigger, LogicalKeyboardKey.altRight) &&
       !identical(trigger, LogicalKeyboardKey.meta) &&
       !identical(trigger, LogicalKeyboardKey.metaLeft) &&
       !identical(trigger, LogicalKeyboardKey.metaRight),
     );