tcell/tty.go

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// Copyright 2021 The TCell Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use file except in compliance with the License.
// You may obtain a copy of the license at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package tcell
import "io"
// Tty is an abstraction of a tty (traditionally "teletype"). This allows applications to
// provide for alternate backends, as there are situations where the traditional /dev/tty
// does not work, or where more flexible handling is required. This interface is for use
// with the terminfo-style based API. It extends the io.ReadWriter API. It is reasonable
// that the implementation might choose to use different underlying files for the Reader
// and Writer sides of this API, as part of it's internal implementation.
type Tty interface {
// Start is used to activate the Tty for use. Upon return the terminal should be
// in raw mode, non-blocking, etc. The implementation should take care of saving
// any state that is required so that it may be restored when Stop is called.
Start() error
// Stop is used to stop using this Tty instance. This may be a suspend, so that other
// terminal based applications can run in the foreground. Implementations should
// restore any state collected at Start(), and return to ordinary blocking mode, etc.
// Drain is called first to drain the input. Once this is called, no more Read
// or Write calls will be made until Start is called again.
Stop() error
// Drain is called before Stop, and ensures that the reader will wake up appropriately
// if it was blocked. This workaround is required for /dev/tty on certain UNIX systems
// to ensure that Read() does not block forever. This typically arranges for the tty driver
// to send data immediately (e.g. VMIN and VTIME both set zero) and sets a deadline on input.
// Implementations may reasonably make this a no-op. There will still be control sequences
// emitted between the time this is called, and when Stop is called.
Drain() error
// NotifyResize is used register a callback when the tty thinks the dimensions have
// changed. The standard UNIX implementation links this to a handler for SIGWINCH.
// If the supplied callback is nil, then any handler should be unregistered.
NotifyResize(cb func())
// WindowSize is called to determine the terminal dimensions. This might be determined
// by an ioctl or other means.
WindowSize() (width int, height int, err error)
io.ReadWriteCloser
}