class TermBuf::Prober

• TermBuf::Prober
• Reference
• Object

Overview

Asks the terminal what it can do, rather than guessing from its name.

Every query goes out in one batch, and the last of them is a cursor position report. Every terminal answers that one, so its reply is the signal that everything else which was going to answer already has. The common case therefore costs one round trip rather than the full timeout, and the timeout is only a backstop for a terminal that answers nothing.

Bytes arriving during the probe window that are not replies are keystrokes. They are handed back rather than dropped, so a key pressed while the application was starting still reaches it.

Defined in:

termbuf/caps/prober.cr

Constant Summary

CURSOR_POSITION = /\A\e\[(\d+);(\d+)R\z/

DEFAULT_TIMEOUT = 250.milliseconds

Long enough for a terminal on the far end of a slow link, short enough not to be noticed when nothing answers.

KITTY_GRAPHICS_QUERY = "\e_Gi=31,s=1,v=1,a=q,t=d,f=24;AAAA\e\\"

A one pixel RGB image, asked about rather than displayed.

KITTY_KEYBOARD = /\A\e\[\?\d*u\z/

PRIMARY_ATTRIBUTES = /\A\e\[\?[\d;]*c\z/

QUERIES = String.build do |io| io << "\e[c" io << "\e[>c" io << "\e[>0q" io << TCAP_QUERY io << "\e[?2026$p" io << "\e[?u" io << KITTY_GRAPHICS_QUERY io << "\e[6n" end

TCAP_QUERY = "\eP+q5463;524742\e\\"

Tc and RGB are the terminfo capabilities that mean 24 bit colour; asking for them by hex name is how XTGETTCAP works.

TERMINAL_NAME = /\A\eP>\|(.*)\e\\\z/m

Constructors

• .new(input : IO, output : IO, timeout : Time::Span = DEFAULT_TIMEOUT)

Instance Method Summary

• #probe(base : Capabilities) : Result

  Sends the queries and folds whatever comes back into base.

• #probe_temp_file : Bool

  Asks whether the terminal will read image data out of a file rather than take it inline.

• #timeout : Time::Span

  How long to wait for the sentinel before giving up on the batch.

Constructor Detail

Instance Method Detail