Problem to solve

Allow desktop and web games to use the second mouse button. The right-click is a common input method for some games. Think deselecting in a city builder, issuing commands in an RTS, or secondary weapon fire in a top-down shooter.

Background

Flame is currently in transition from the TapDetector-Tappable API to the newer HasTappableComponents -TapCallbacks API. The old TapDetector API doesn't seem to work with the new CameraComponent API (at least I can't make it work - I always get screen coords, never game coords). The new API is better in every way, except that its callbacks don't give info about the button (primary / secondary / tertiary).

The new API's main workhorse class is HasTappableComponents (a mixin on Game). This class implements MultiTapListener, and that class is a facade to Flutter framework's MultiTapGestureRecognizer (code here).

The problem: Flutter's MultiTapGestureRecognizer doesn't have a concept of the right click. If Flame uses MultiTapGestureRecognizer as the underlying API, it cannot support secondary mouse button action.

Proposal

I'm not sure where the new API is heading, so I can only offer a newcomer's view. I'm guessing I would add a new class, SingleTapListener, that closely follows MultiTapListener in functionality. This class would be "the new TapDetector" — it would forward events from Flutter's TapGestureRecognizer, but in the new way that respects the CameraComponent.

The old TapDetector and the new SingleTapListener would likely have to be exclusive (you either implement from one or the other).

HasTappableComponents would then implement the new SingleTapListener alongside the MultiTapListener, and would send the event down (like so).

The TapDownEvent class would gain a new member, pointerEvent, which would just copy Flutter's PointerEvent. This const class has everything anyone could need, including pressure, tilt, kind, buttons, etc. The primary / secondary / tertiary button is easily extracted from PointerEvent.buttons.

More information

• This has been discussed on Discord here and here
• I'm very new to the codebase but I'm willing to have a stab at it. I do need someone to give me the blessing. As I mentioned, I have no idea where the new API is heading. I might be misreading the direction.