module TermBuf::SizeDetector

Overview

Works out how big the terminal is, trying each source in turn and taking the first that answers.

The ioctl comes first because it is exact, free, and needs no cooperation from the terminal. Everything after it is a fallback for the cases where there is no controlling terminal to ask — a pipe, a pty without a size set, a terminal reached across a connection that did not forward one.

Extended Modules

• TermBuf::SizeDetector

Defined in:

termbuf/caps/screen_size.cr

Constant Summary

TIOCGWINSZ = 21523_u64

Instance Method Summary

• #detect(fd : Int32 | Nil = nil, env : Hash(String, String) = ENV.to_h) : ScreenSize

  In order: the kernel, the environment, then the shell utilities.

• #from_commands : ScreenSize | Nil

  stty and tput, which reach the same ioctl by another route.

• #from_env(env : Hash(String, String)) : ScreenSize | Nil

  COLUMNS and LINES, which a shell exports and which can be set by hand when nothing else knows.

• #from_ioctl(fd : Int32 | Nil = nil) : ScreenSize | Nil

  TIOCGWINSZ on the given descriptor, or on stdout, stdin, and stderr in turn when none is named.

Instance Method Detail