Keyboard input

Apps can capture input from the user by reading key presses and passing them to the active widget.

Each widget must have a controls attribute with a dictionary mapping keys to function. The keys of this dictionary can take one of two types:

  • Char: a single character. Used to map a "letter" key to a function. For example q generally quits the app and h displays help.
  • a KeyInput type like ArrowLeft() or HomeKey(). These are special keys including the arrows, page up/down, Esc, Del and SpaceBar.

The values of the dictionary are functions. The function should have a signature: fn(w, k) where w is the widget they are assigned to and k is the key that was pressed. For example in Pager you can use ArrowRight, PageDownKey and ] to scroll down so a function is defined as:

next_page(p::Pager, ::Union{PageDownKey,ArrowRight,Char})

and with similar functions the controls for Pager are:

pager_controls = Dict(
    ArrowRight() => next_page,
    ']' => next_page,
    ArrowLeft() => prev_page,
    '[' => prev_page,
    ArrowDown() => next_line,
    '.' => next_line,
    ArrowUp() => prev_line,
    ',' => prev_line,
    HomeKey() => home,
    EndKey() => toend,
    Esc() => quit,
    'q' => quit,

there's no restriction to which/how many control functions you should have and how they should affect your widget. However having quit is generally a good idea or the user can't quit the app while that widget is active! Different widgets will have different controls. A widget's controls are only activated if the corresponding key is pressed while the widget is active.