ESPTerm web interface submodule, separated to make testing and development easier
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espterm-front-end/js/term/screen_parser.js

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const $ = require('../lib/chibi')
const { qs, parse2B, parse3B } = require('../utils')
const { themes } = require('./themes')
// constants for decoding the update blob
const SEQ_REPEAT = 2
const SEQ_SET_COLORS = 3
const SEQ_SET_ATTRS = 4
const SEQ_SET_FG = 5
const SEQ_SET_BG = 6
module.exports = class ScreenParser {
constructor (screen) {
this.screen = screen
// true if TermScreen#load was called at least once
this.contentLoaded = false
}
/**
* Parses the content of an `S` message and schedules a draw
* @param {string} str - the message content
*/
loadContent (str) {
// current index
let i = 0
// Uncomment to capture screen content for the demo page
// console.log(JSON.stringify(`S${str}`))
if (!this.contentLoaded) {
let errmsg = qs('#load-failed')
if (errmsg) errmsg.parentNode.removeChild(errmsg)
this.contentLoaded = true
}
// window size
const newHeight = parse2B(str, i)
const newWidth = parse2B(str, i + 2)
const resized = (this.screen.window.height !== newHeight) || (this.screen.window.width !== newWidth)
this.screen.window.height = newHeight
this.screen.window.width = newWidth
i += 4
// cursor position
let [cursorY, cursorX] = [parse2B(str, i), parse2B(str, i + 2)]
i += 4
let cursorMoved = (cursorX !== this.screen.cursor.x || cursorY !== this.screen.cursor.y)
this.screen.cursor.x = cursorX
this.screen.cursor.y = cursorY
if (cursorMoved) {
this.screen.renderer.resetCursorBlink()
this.screen.emit('cursor-moved')
}
// attributes
let attributes = parse3B(str, i)
i += 3
this.screen.cursor.visible = !!(attributes & 1)
this.screen.cursor.hanging = !!(attributes & (1 << 1))
this.screen.input.setAlts(
!!(attributes & (1 << 2)), // cursors alt
!!(attributes & (1 << 3)), // numpad alt
!!(attributes & (1 << 4)), // fn keys alt
!!(attributes & (1 << 12)) // crlf mode
)
let trackMouseClicks = !!(attributes & (1 << 5))
let trackMouseMovement = !!(attributes & (1 << 6))
// 0 - Block blink 2 - Block steady (1 is unused)
// 3 - Underline blink 4 - Underline steady
// 5 - I-bar blink 6 - I-bar steady
let cursorShape = (attributes >> 9) & 0x07
// if it's not zero, decrement such that the two most significant bits
// are the type and the least significant bit is the blink state
if (cursorShape > 0) cursorShape--
let cursorStyle = cursorShape >> 1
let cursorBlinking = !(cursorShape & 1)
if (cursorStyle === 0) this.screen.cursor.style = 'block'
else if (cursorStyle === 1) this.screen.cursor.style = 'line'
else if (cursorStyle === 2) this.screen.cursor.style = 'bar'
if (this.screen.cursor.blinking !== cursorBlinking) {
this.screen.cursor.blinking = cursorBlinking
this.screen.renderer.resetCursorBlink()
}
this.screen.input.setMouseMode(trackMouseClicks, trackMouseMovement)
this.screen.selection.selectable = !trackMouseClicks && !trackMouseMovement
$(this.screen.canvas).toggleClass('selectable', this.screen.selection.selectable)
this.screen.mouseMode = {
clicks: trackMouseClicks,
movement: trackMouseMovement
}
let showButtons = !!(attributes & (1 << 7))
let showConfigLinks = !!(attributes & (1 << 8))
$('.x-term-conf-btn').toggleClass('hidden', !showConfigLinks)
$('#action-buttons').toggleClass('hidden', !showButtons)
this.screen.bracketedPaste = !!(attributes & (1 << 13))
// content
let fg = 7
let bg = 0
let attrs = 0
let cell = 0 // cell index
let lastChar = ' '
let screenLength = this.screen.window.width * this.screen.window.height
if (resized) {
this.screen.updateSize()
this.screen.blinkingCellCount = 0
this.screen.screen = new Array(screenLength).fill(' ')
this.screen.screenFG = new Array(screenLength).fill(' ')
this.screen.screenBG = new Array(screenLength).fill(' ')
this.screen.screenAttrs = new Array(screenLength).fill(' ')
}
let strArray = Array.from ? Array.from(str) : str.split('')
const MASK_LINE_ATTR = 0xC8
const MASK_BLINK = 1 << 4
let setCellContent = () => {
// Remove blink attribute if it wouldn't have any effect
let myAttrs = attrs
if ((myAttrs & MASK_BLINK) !== 0 &&
((lastChar === ' ' && ((myAttrs & MASK_LINE_ATTR) === 0)) || // no line styles
fg === bg // invisible text
)
) {
myAttrs ^= MASK_BLINK
}
// update blinking cells counter if blink state changed
if ((this.screen.screenAttrs[cell] & MASK_BLINK) !== (myAttrs & MASK_BLINK)) {
if (myAttrs & MASK_BLINK) this.screen.blinkingCellCount++
else this.screen.blinkingCellCount--
}
this.screen.screen[cell] = lastChar
this.screen.screenFG[cell] = fg
this.screen.screenBG[cell] = bg
this.screen.screenAttrs[cell] = myAttrs
}
while (i < strArray.length && cell < screenLength) {
let character = strArray[i++]
let charCode = character.codePointAt(0)
let data
switch (charCode) {
case SEQ_REPEAT:
let count = parse2B(strArray[i] + strArray[i + 1])
i += 2
for (let j = 0; j < count; j++) {
setCellContent(cell)
if (++cell > screenLength) break
}
break
case SEQ_SET_COLORS:
data = parse3B(strArray[i] + strArray[i + 1] + strArray[i + 2])
i += 3
fg = data & 0xFF
bg = (data >> 8) & 0xFF
break
case SEQ_SET_ATTRS:
data = parse2B(strArray[i] + strArray[i + 1])
i += 2
attrs = data & 0xFF
break
case SEQ_SET_FG:
data = parse2B(strArray[i] + strArray[i + 1])
i += 2
fg = data & 0xFF
break
case SEQ_SET_BG:
data = parse2B(strArray[i] + strArray[i + 1])
i += 2
bg = data & 0xFF
break
default:
if (charCode < 32) character = '\ufffd'
lastChar = character
setCellContent(cell)
cell++
}
}
if (this.screen.window.debug) console.log(`Blinky cells: ${this.screen.blinkingCellCount}`)
this.screen.renderer.scheduleDraw('load', 16)
this.screen.emit('load')
}
/**
* Parses the content of a `T` message and updates the screen title and button
* labels.
* @param {string} str - the message content
*/
loadLabels (str) {
let pieces = str.split('\x01')
let screenTitle = pieces[0]
qs('#screen-title').textContent = screenTitle
if (screenTitle.length === 0) screenTitle = 'Terminal'
qs('title').textContent = `${screenTitle} :: ESPTerm`
$('#action-buttons button').forEach((button, i) => {
let label = pieces[i + 1].trim()
// if empty string, use the "dim" effect and put nbsp instead to
// stretch the button vertically
button.innerHTML = label ? $.htmlEscape(label) : '&nbsp;'
button.style.opacity = label ? 1 : 0.2
})
}
/**
* Loads a message from the server, and optionally a theme.
* @param {string} str - the message
* @param {number} [theme] - the new theme index
*/
load (str, theme = -1) {
const content = str.substr(1)
if (theme >= 0 && theme < themes.length) {
this.screen.renderer.palette = themes[theme]
}
switch (str[0]) {
case 'S':
this.loadContent(content)
break
case 'T':
this.loadLabels(content)
break
case 'B':
this.screen.beep()
break
case 'G':
this.screen.showNotification(content)
break
default:
console.warn(`Bad data message type; ignoring.\n${JSON.stringify(str)}`)
}
}
}