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const ansi = require('../util/ansi')
const DisplayElement = require('./DisplayElement')
const FocusElement = require('./form/FocusElement')
module.exports = class Root extends DisplayElement {
// An element to be used as the root of a UI. Handles lots of UI and
// socket stuff.
constructor(interfacer) {
super()
this.interfacer = interfacer
this.selectedElement = null
this.cursorBlinkOffset = Date.now()
this.oldSelectionStates = []
interfacer.on('inputData', buf => this.handleData(buf))
}
render() {
this.renderTo(this.interfacer)
}
handleData(buffer) {
if (this.selectedElement) {
const els = [
this.selectedElement, ...this.selectedElement.directAncestors]
for (const el of els) {
if (el instanceof FocusElement) {
const shouldBreak = (el.keyPressed(buffer) === false)
if (shouldBreak) {
break
}
el.emit('keypressed', buffer)
}
}
}
}
drawTo(writable) {
writable.write(ansi.moveCursor(0, 0))
writable.write(' '.repeat(this.w * this.h))
}
didRenderTo(writable) {
// Render the cursor, based on the cursorX and cursorY of the currently
// selected element.
if (this.selectedElement && this.selectedElement.cursorVisible) {
if ((Date.now() - this.cursorBlinkOffset) % 1000 < 500) {
writable.write(ansi.moveCursor(
this.selectedElement.absCursorY, this.selectedElement.absCursorX))
writable.write(ansi.invert())
writable.write('I')
writable.write(ansi.resetAttributes())
}
writable.write(ansi.showCursor())
writable.write(ansi.moveCursor(
this.selectedElement.absCursorY, this.selectedElement.absCursorX))
} else {
writable.write(ansi.hideCursor())
}
}
cursorMoved() {
// Resets the blinking animation for the cursor. Call this whenever you
// move the cursor.
this.cursorBlinkOffset = Date.now()
}
select(el) {
// Select an element. Calls the unfocus method on the already-selected
// element, if there is one.
const oldSelected = this.selectedElement
const newSelected = el
// Relevant elements that COULD have their "isSelected" state change.
const relevantElements = ([
...(oldSelected ? [...oldSelected.directAncestors, oldSelected] : []),
...(newSelected ? newSelected.directAncestors : [])
]
// We ignore elements where isSelected is undefined, because they aren't
// built to handle being selected, and they break the compare-old-and-new-
// state code below.
.filter(el => typeof el.isSelected !== 'undefined')
// Get rid of duplicates - including any that occurred in the already
// existing array of selection states. (We only care about the oldest
// selection state, i.e. the one when we did the first .select().)
.reduce((acc, el) => {
// Duplicates from relevant elements of current .select()
if (acc.includes(el)) return acc
// Duplicates from already existing selection states
if (this.oldSelectionStates.some(x => x[0] === el)) return acc
return acc.concat([el])
}, []))
// Keep track of whether those elements were selected before we call the
// newly selected element's selected() function. We store these on a
// property because we might actually be adding to it from a previous
// root.select() call, if that one itself caused this root.select().
// One all root.select()s in the "chain" (as it is) have finished, we'll
// go through these states and call the appropriate .select/unselect()
// functions on each element whose .isSelected changed.
const selectionStates = relevantElements.map(el => [el, el.isSelected])
this.oldSelectionStates = this.oldSelectionStates.concat(selectionStates)
this.selectedElement = el
// Same stuff as in the for loop below. We always call selected() on the
// passed element, even if it was already selected before.
if (el.selected) el.selected()
if (typeof el.focused === 'function') el.focused()
// If the selection changed as a result of the element's selected()
// function, stop here. We will leave calling the appropriate functions on
// the elements in the oldSelectionStates array to the final .select(),
// i.e. the one which caused no change in selected element.
if (this.selectedElement !== newSelected) return
// Compare the old "isSelected" state of every relevant element with their
// current "isSelected" state, and call the respective selected/unselected
// functions. (Also call focused and unfocused for some sense of trying to
// not break old programs, but, like, old programs are going to be broken
// anyways.)
const states = this.oldSelectionStates.slice()
for (const [ el, wasSelected ] of states) {
// Now that we'll have processed it, we don't want it in the array
// anymore.
this.oldSelectionStates.shift()
const { isSelected } = el
if (isSelected && !wasSelected) {
// Don't call these functions if this element is the newly selected
// one, because we already called them above!
if (el !== newSelected) {
if (el.selected) el.selected()
if (typeof el.focused === 'function') el.focused()
}
} else if (wasSelected && !isSelected) {
if (el.unselected) el.unselected()
if (typeof el.unfocused === 'function') el.unfocused()
}
// If the (un)selected() handler actually selected a different element
// itself, then further processing of new selected states is irrelevant,
// so stop here. (We return instead of breaking the for loop because
// anything after this loop would have already been handled by the call
// to Root.select() from the (un)selected() handler.)
if (this.selectedElement !== newSelected) {
return
}
}
this.cursorMoved()
}
isChildOrSelfSelected(el) {
if (!this.selectedElement) return false
if (this.selectedElement === el) return true
if (this.selectedElement.directAncestors.includes(el)) return true
return false
}
}
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