Translations:Basic concept/8/en

Event handling

There are 5 stage of event handling for one event, only 3 of the stages are exposed to user, which are Default, PreInputMethod, and PostInputMethod. There are also ReservedFirst and ReservedLast used by Fcitx internally. The order of different stages is ReservedFirst, PreInputMethod, Default, PostInputMethod, ReservedLast. The Default stage just after the active input method engine receives event. PreInputMethod is one of the most commonly used one to implement sub input method. For example, an addon may define a trigger key. When the trigger key is pressed by user, it sets a flag and handle all the future key event in the PreInputMethod stage until it ends its input mode.