class TermBuf::Encoder

• TermBuf::Encoder
• Reference
• Object

Overview

Turns paint operations into terminal bytes, as few of them as it can.

The encoder carries the state the terminal has: where the cursor is and what style is in force. That is what lets it drop a MoveTo that is already true, pick the shortest of the half-dozen ways to move the cursor a few columns, and emit an SGR delta instead of a reset plus everything.

It also holds the capability mask, and is the only place a style is narrowed to what the terminal can actually render. Colours are downgraded here rather than at write time, so the buffer keeps full fidelity and a later repaint against a wider mask comes out better.

Defined in:

termbuf/core/encoder.cr

Constant Summary

CSI = "\e["

RESETS = { {Attributes::Italic, "23"}, {Attributes::Reverse, "27"}, {Attributes::Conceal, "28"}, {Attributes::Strike, "29"}, {Attributes::Overline, "55"} }

Attributes with a reset of their own.

SHARED_RESETS = { {Attributes::Bold | Attributes::Faint, "22"}, {Attributes::SlowBlink | Attributes::RapidBlink, "25"}, {Attributes::Superscript | Attributes::Subscript, "75"} }

Attributes that share a reset with a sibling: turning one off turns the whole group off, so any member that should survive has to be reasserted.

Constructors

• .new(styles : StyleTable, capabilities : Capabilities, width : Int32, height : Int32)

Instance Method Summary

• #capabilities : Capabilities

  What the terminal can do.

• #capabilities=(capabilities : Capabilities) : Capabilities

  Replaces the capability mask, discarding the style cache built under the old one.

• #cursor_x : Int32 | Nil

  Where the terminal's cursor is, or nil when it is not known and the next move has to be absolute.

• #cursor_y : Int32 | Nil

  Where the terminal's cursor is, or nil when it is not known and the next move has to be absolute.

• #effective(id : StyleId) : Style

  The style as this terminal can actually render it: unsupported attributes dropped, colours narrowed to the deepest supported space.

• #encode(ops : Array(Op), io : IO) : Nil

  Encodes ops straight to io.

• #encode(ops : Array(Op)) : String

  Encodes ops and returns the bytes.

• #move_to(x : Int32, y : Int32, io : IO) : Nil

  Emits the shortest sequence that puts the cursor at (x, y).

• #reset_state : Nil

  Forgets what the terminal was showing.

• #resize(width : Int32, height : Int32) : Nil

  Tells the encoder the screen changed size, and forgets where the cursor was.

• #set_style(id : StyleId, io : IO) : Nil

  Emits whatever SGR takes the terminal from the style it is in to id, after capabilities have had their say.

Constructor Detail

Instance Method Detail