Hotkeys (architecture)

General

Across the chapters, the following definitions shall apply:

Hotkey Source (Device): Implementation or device object, which can trigger a hotkey function, e.g. keyboard, joystick, remote event

Hotkey Action: String based object with hierarchical syntax, describing and grouping hotkey purpose, e.g. push-to-talk

Hotkey Receiver Object: Any kind of object which registers one if its methods for a Hotkey Function

Object Interface Overview

Different objects and interfaces are involved and will be explained in details below

Interface CInputManager vs. Hotkey Receiver Objects

First of all a hotkey receiver object is an object which exposes one or more of its methods as hotkey method. Typical examples are CContextAudio for push to talk and GUI for different GUI hotkeys.

Sources and receivers of a hotkey action are not coupled. A receiver does not know which source triggered the hotkey action. The same is applicable the other way round. A source does not know, which hotkey function it might trigger - if any. The mapping logic is done in CInputManager. It is the central node wiring source and receiver together.

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Hotkey receiver objects bind a method to a hotkey action. The hotkey action is a string with a hierarchical syntax, e.g. /Test/Message. Test stands for an arbitrary group into which Message belongs. This syntax can be used to logically group hotkeys together. No Hotkey Source is involved at this stage (no keyboard keys, no joystick etc). To the object itself it is transparent which Hotkey Source the call had issued.

Usage example: BlackCore::CActionBind m_action { "/Test/Message", this, &CFoo::bar };

Interface CInputManager vs. Hotkey Source (Device)

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CInputManager will feed all configured keys/buttons to the corresponding device interface. Registered CKeyboardKeys will be registered in IKeyboard, joystick buttons will be registered in IJoystick. IKeyboard and IJoystick will signal back if one of the registered keys/buttons have been pressed. No actions are involved at this stage. CInputManager knows, which Hotkey Receiver Objects are registered and will call their functions.

Advantages:

  • Only keys need to be registered which have to be monitored locally
  • Can be extended easily by adding a new input device.

Hotkey Action forwarding to Remote

Hotkey actions do not have to be limited to local execution. If forwarding is enabled, all triggered actions will be forwarded to a remote process running on any machine. This allows for example to configure a push to talk hotkey on one machine, even though core is running in a different process.

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Advantages:

  • Only one event type is required, even if more input devices are added
  • Remote CInputManager does not need to know the configuration of the local GUI, it will just react on the given inputs from DBus.

Interface CInputManager vs. Settings

CInputManager is interfacing with the settings API. The list of action hotkeys - which is the mapping between a hotkey combination and the hotkey action is loaded during start up and modifications saved to disk.

Summary

The design is conceptual only. It addresses the new requirements of different instead of only one input device. Input has to be transparent (keyboard, joystick, event, anything else) and decoupling of different objects is IMHO good OO design. It hopefully reduces complexity within swift a lot.

Last modified 28.06.2020: Add content (0e00ae5)