The zsh/curses Module (zsh)

### 22.9 The zsh/curses Module ¶

The `zsh/curses` module makes available one builtin command and various parameters.

#### 22.9.1 Builtin ¶

`zcurses` `init` ¶
`zcurses` `end`
`zcurses` `addwin` targetwin nlines ncols begin_y begin_x [ parentwin ]
`zcurses` `delwin` targetwin
`zcurses` `refresh` [ targetwin ... ]
`zcurses` `touch` targetwin ...
`zcurses` `move` targetwin new_y new_x
`zcurses` `clear` targetwin [ `redraw` | `eol` | `bot` ]
`zcurses` `position` targetwin array
`zcurses` `char` targetwin character
`zcurses` `string` targetwin string
`zcurses` `border` targetwin border
`zcurses` `attr` targetwin [ [`+`|`-`]attribute | fg_col`/`bg_col ] [...]
`zcurses` `bg` targetwin [ [`+`|`-`]attribute | fg_col`/`bg_col | `@`char ] [...]
`zcurses` `scroll` targetwin [ `on` | `off` | [`+`|`-`]lines ]
`zcurses` `input` targetwin [ param [ kparam [ mparam ] ] ]
`zcurses` `mouse` [ `delay` num | [`+`|`-`]`motion` ]
`zcurses` `timeout` targetwin intval
`zcurses` `querychar` targetwin [ param ]
`zcurses` `resize` height width [ `endwin` | `nosave` | `endwin_nosave` ]

  Manipulate curses windows. All uses of this command should be bracketed by ‘`zcurses init`’ to initialise use of curses, and ‘`zcurses end`’ to end it; omitting ‘`zcurses end`’ can cause the terminal to be in an unwanted state.

  The subcommand `addwin` creates a window with nlines lines and ncols columns. Its upper left corner will be placed at row begin_y and column begin_x of the screen. targetwin is a string and refers to the name of a window that is not currently assigned. Note in particular the curses convention that vertical values appear before horizontal values.

  If `addwin` is given an existing window as the final argument, the new window is created as a subwindow of parentwin. This differs from an ordinary new window in that the memory of the window contents is shared with the parent’s memory. Subwindows must be deleted before their parent. Note that the coordinates of subwindows are relative to the screen, not the parent, as with other windows.

  Use the subcommand `delwin` to delete a window created with `addwin`. Note that `end` does not implicitly delete windows, and that `delwin` does not erase the screen image of the window.

  The window corresponding to the full visible screen is called `stdscr`; it always exists after ‘`zcurses init`’ and cannot be delete with `delwin`.

  The subcommand `refresh` will refresh window targetwin; this is necessary to make any pending changes (such as characters you have prepared for output with `char`) visible on the screen. `refresh` without an argument causes the screen to be cleared and redrawn. If multiple windows are given, the screen is updated once at the end.

  The subcommand `touch` marks the targetwins listed as changed. This is necessary before `refresh`ing windows if a window that was in front of another window (which may be `stdscr`) is deleted.

  The subcommand `move` moves the cursor position in targetwin to new coordinates new_y and new_x. Note that the subcommand `string` (but not the subcommand `char`) advances the cursor position over the characters added.

  The subcommand `clear` erases the contents of targetwin. One (and no more than one) of three options may be specified. With the option `redraw`, in addition the next `refresh` of targetwin will cause the screen to be cleared and repainted. With the option `eol`, targetwin is only cleared to the end of the current cursor line. With the option `bot`, targetwin is cleared to the end of the window, i.e everything to the right and below the cursor is cleared.

  The subcommand `position` writes various positions associated with targetwin into the array named array. These are, in order:

  -

    The y and x coordinates of the cursor relative to the top left of targetwin

  -

    The y and x coordinates of the top left of targetwin on the screen

  -

    The size of targetwin in y and x dimensions.

  Outputting characters and strings are achieved by `char` and `string` respectively.

  To draw a border around window targetwin, use `border`. Note that the border is not subsequently handled specially: in other words, the border is simply a set of characters output at the edge of the window. Hence it can be overwritten, can scroll off the window, etc.

  The subcommand `attr` will set targetwin’s attributes or foreground/background color pair for any successive character output. Each attribute given on the line may be prepended by a `+` to set or a `-` to unset that attribute; `+` is assumed if absent. The attributes supported are `blink`, `bold`, `dim`, `reverse`, `standout`, and `underline`.

  Each fg_col`/`bg_col attribute (to be read as ‘fg_col on bg_col’) sets the foreground and background color for character output. The color `default` is sometimes available (in particular if the library is ncurses), specifying the foreground or background color with which the terminal started. The color pair `default/default` is always available. To use more than the 8 named colors (red, green, etc.) construct the fg_col`/`bg_col pairs where fg_col and bg_col are decimal integers, e.g `128/200`. The maximum color value is 254 if the terminal supports 256 colors.

  `bg` overrides the color and other attributes of all characters in the window. Its usual use is to set the background initially, but it will overwrite the attributes of any characters at the time when it is called. In addition to the arguments allowed with `attr`, an argument `@`char specifies a character to be shown in otherwise blank areas of the window. Owing to limitations of curses this cannot be a multibyte character (use of ASCII characters only is recommended). As the specified set of attributes override the existing background, turning attributes off in the arguments is not useful, though this does not cause an error.

  The subcommand `scroll` can be used with `on` or `off` to enabled or disable scrolling of a window when the cursor would otherwise move below the window due to typing or output. It can also be used with a positive or negative integer to scroll the window up or down the given number of lines without changing the current cursor position (which therefore appears to move in the opposite direction relative to the window). In the second case, if scrolling is `off` it is temporarily turned `on` to allow the window to be scrolled.

  The subcommand `input` reads a single character from the window without echoing it back. If param is supplied the character is assigned to the parameter param, else it is assigned to the parameter `REPLY`.

  If both param and kparam are supplied, the key is read in ‘keypad’ mode. In this mode special keys such as function keys and arrow keys return the name of the key in the parameter kparam. The key names are the macros defined in the `curses.h` or `ncurses.h` with the prefix ‘`KEY_`’ removed; see also the description of the parameter `zcurses_keycodes` below. Other keys cause a value to be set in param as before. On a successful return only one of param or kparam contains a non-empty string; the other is set to an empty string.

  If mparam is also supplied, `input` attempts to handle mouse input. This is only available with the ncurses library; mouse handling can be detected by checking for the exit status of ‘`zcurses mouse`’ with no arguments. If a mouse button is clicked (or double- or triple-clicked, or pressed or released with a configurable delay from being clicked) then kparam is set to the string `MOUSE`, and mparam is set to an array consisting of the following elements:

  -

    An identifier to discriminate different input devices; this is only rarely useful.

  -

    The x, y and z coordinates of the mouse click relative to the full screen, as three elements in that order (i.e. the y coordinate is, unusually, after the x coordinate). The z coordinate is only available for a few unusual input devices and is otherwise set to zero.

  -

    Any events that occurred as separate items; usually there will be just one. An event consists of `PRESSED`, `RELEASED`, `CLICKED`, `DOUBLE_CLICKED` or `TRIPLE_CLICKED` followed immediately (in the same element) by the number of the button.

  -

    If the shift key was pressed, the string `SHIFT`.

  -

    If the control key was pressed, the string `CTRL`.

  -

    If the alt key was pressed, the string `ALT`.

  Not all mouse events may be passed through to the terminal window; most terminal emulators handle some mouse events themselves. Note that the ncurses manual implies that using input both with and without mouse handling may cause the mouse cursor to appear and disappear.

  The subcommand `mouse` can be used to configure the use of the mouse. There is no window argument; mouse options are global. ‘`zcurses mouse`’ with no arguments returns status 0 if mouse handling is possible, else status 1. Otherwise, the possible arguments (which may be combined on the same command line) are as follows. `delay` num sets the maximum delay in milliseconds between press and release events to be considered as a click; the value 0 disables click resolution, and the default is one sixth of a second. `motion` proceeded by an optional ‘`+`’ (the default) or `-` turns on or off reporting of mouse motion in addition to clicks, presses and releases, which are always reported. However, it appears reports for mouse motion are not currently implemented.

  The subcommand `timeout` specifies a timeout value for input from targetwin. If intval is negative, ‘`zcurses input`’ waits indefinitely for a character to be typed; this is the default. If intval is zero, ‘`zcurses input`’ returns immediately; if there is typeahead it is returned, else no input is done and status 1 is returned. If intval is positive, ‘`zcurses input`’ waits intval milliseconds for input and if there is none at the end of that period returns status 1.

  The subcommand `querychar` queries the character at the current cursor position. The return values are stored in the array named param if supplied, else in the array `reply`. The first value is the character (which may be a multibyte character if the system supports them); the second is the color pair in the usual fg_col`/`bg_col notation, or `0` if color is not supported. Any attributes other than color that apply to the character, as set with the subcommand `attr`, appear as additional elements.

  The subcommand `resize` resizes `stdscr` and all windows to given dimensions (windows that stick out from the new dimensions are resized down). The underlying curses extension (`resize_term call`) can be unavailable. To verify, zeroes can be used for height and width. If the result of the subcommand is `0`, resize_term is available (`2` otherwise). Tests show that resizing can be normally accomplished by calling `zcurses end` and `zcurses refresh`. The `resize` subcommand is provided for versatility. Multiple system configurations have been checked and `zcurses end` and `zcurses refresh` are still needed for correct terminal state after resize. To invoke them with `resize`, use endwin argument. Using nosave argument will cause new terminal state to not be saved internally by `zcurses`. This is also provided for versatility and should normally be not needed.

#### 22.9.2 Parameters ¶

`ZCURSES_COLORS` ¶

  Readonly integer. The maximum number of colors the terminal supports. This value is initialised by the curses library and is not available until the first time `zcurses init` is run.

`ZCURSES_COLOR_PAIRS` ¶

  Readonly integer. The maximum number of color pairs fg_col`/`bg_col that may be defined in ‘`zcurses attr`’ commands; note this limit applies to all color pairs that have been used whether or not they are currently active. This value is initialised by the curses library and is not available until the first time `zcurses init` is run.

`zcurses_attrs` ¶

  Readonly array. The attributes supported by `zsh/curses`; available as soon as the module is loaded.

`zcurses_colors` ¶

  Readonly array. The colors supported by `zsh/curses`; available as soon as the module is loaded.

`zcurses_keycodes` ¶

  Readonly array. The values that may be returned in the second parameter supplied to ‘`zcurses input`’ in the order in which they are defined internally by curses. Not all function keys are listed, only `F0`; curses reserves space for `F0` up to `F63`.

`zcurses_windows` ¶

  Readonly array. The current list of windows, i.e. all windows that have been created with ‘`zcurses addwin`’ and not removed with ‘`zcurses delwin`’.