quasar/src/utils/private.position-engine/position-engine.js

Build high-performance VueJS user interfaces (SPA, PWA, SSR, Mobile and Desktop) in record time

import { getScrollbarWidth } from '../scroll/scroll.js'
import { client } from '../../plugins/platform/Platform.js'

let vpLeft, vpTop

export function validatePosition (pos) {
  const parts = pos.split(' ')
  if (parts.length !== 2) {
    return false
  }
  if ([ 'top', 'center', 'bottom' ].includes(parts[ 0 ]) !== true) {
    console.error('Anchor/Self position must start with one of top/center/bottom')
    return false
  }
  if ([ 'left', 'middle', 'right', 'start', 'end' ].includes(parts[ 1 ]) !== true) {
    console.error('Anchor/Self position must end with one of left/middle/right/start/end')
    return false
  }
  return true
}

export function validateOffset (val) {
  if (!val) { return true }
  if (val.length !== 2) { return false }
  if (typeof val[ 0 ] !== 'number' || typeof val[ 1 ] !== 'number') {
    return false
  }
  return true
}

const horizontalPos = {
  'start#ltr': 'left',
  'start#rtl': 'right',
  'end#ltr': 'right',
  'end#rtl': 'left'
}

;[ 'left', 'middle', 'right' ].forEach(pos => {
  horizontalPos[ `${ pos }#ltr` ] = pos
  horizontalPos[ `${ pos }#rtl` ] = pos
})

export function parsePosition (pos, rtl) {
  const parts = pos.split(' ')
  return {
    vertical: parts[ 0 ],
    horizontal: horizontalPos[ `${ parts[ 1 ] }#${ rtl === true ? 'rtl' : 'ltr' }` ]
  }
}

export function getAnchorProps (el, offset) {
  let { top, left, right, bottom, width, height } = el.getBoundingClientRect()

  if (offset !== void 0) {
    top -= offset[ 1 ]
    left -= offset[ 0 ]
    bottom += offset[ 1 ]
    right += offset[ 0 ]

    width += offset[ 0 ]
    height += offset[ 1 ]
  }

  return {
    top, bottom, height,
    left, right, width,
    middle: left + (right - left) / 2,
    center: top + (bottom - top) / 2
  }
}

function getAbsoluteAnchorProps (el, absoluteOffset, offset) {
  let { top, left } = el.getBoundingClientRect()

  top += absoluteOffset.top
  left += absoluteOffset.left

  if (offset !== void 0) {
    top += offset[ 1 ]
    left += offset[ 0 ]
  }

  return {
    top, bottom: top + 1, height: 1,
    left, right: left + 1, width: 1,
    middle: left,
    center: top
  }
}

function getTargetProps (width, height) {
  return {
    top: 0,
    center: height / 2,
    bottom: height,
    left: 0,
    middle: width / 2,
    right: width
  }
}

function getTopLeftProps (anchorProps, targetProps, anchorOrigin, selfOrigin) {
  return {
    top: anchorProps[ anchorOrigin.vertical ] - targetProps[ selfOrigin.vertical ],
    left: anchorProps[ anchorOrigin.horizontal ] - targetProps[ selfOrigin.horizontal ]
  }
}

export function setPosition (cfg, retryNumber = 0) {
  if (
    cfg.targetEl === null
    || cfg.anchorEl === null
    || retryNumber > 5 // we should try only a few times
  ) {
    return
  }

  // some browsers report zero height or width because
  // we are trying too early to get these dimensions
  if (cfg.targetEl.offsetHeight === 0 || cfg.targetEl.offsetWidth === 0) {
    setTimeout(() => {
      setPosition(cfg, retryNumber + 1)
    }, 10)
    return
  }

  const {
    targetEl,
    offset,
    anchorEl,
    anchorOrigin,
    selfOrigin,
    absoluteOffset,
    fit,
    cover,
    maxHeight,
    maxWidth
  } = cfg

  if (client.is.ios === true && window.visualViewport !== void 0) {
    // uses the q-position-engine CSS class

    const el = document.body.style
    const { offsetLeft: left, offsetTop: top } = window.visualViewport

    if (left !== vpLeft) {
      el.setProperty('--q-pe-left', left + 'px')
      vpLeft = left
    }
    if (top !== vpTop) {
      el.setProperty('--q-pe-top', top + 'px')
      vpTop = top
    }
  }

  // scroll position might change
  // if max-height/-width changes, so we
  // need to restore it after we calculate
  // the new positioning
  const { scrollLeft, scrollTop } = targetEl

  const anchorProps = absoluteOffset === void 0
    ? getAnchorProps(anchorEl, cover === true ? [ 0, 0 ] : offset)
    : getAbsoluteAnchorProps(anchorEl, absoluteOffset, offset)

  // we "reset" the critical CSS properties
  // so we can take an accurate measurement
  Object.assign(targetEl.style, {
    top: 0,
    left: 0,
    minWidth: null,
    minHeight: null,
    maxWidth: maxWidth || '100vw',
    maxHeight: maxHeight || '100vh',
    visibility: 'visible'
  })

  const { offsetWidth: origElWidth, offsetHeight: origElHeight } = targetEl
  const { elWidth, elHeight } = fit === true || cover === true
    ? { elWidth: Math.max(anchorProps.width, origElWidth), elHeight: cover === true ? Math.max(anchorProps.height, origElHeight) : origElHeight }
    : { elWidth: origElWidth, elHeight: origElHeight }

  let elStyle = { maxWidth, maxHeight }

  if (fit === true || cover === true) {
    elStyle.minWidth = anchorProps.width + 'px'
    if (cover === true) {
      elStyle.minHeight = anchorProps.height + 'px'
    }
  }

  Object.assign(targetEl.style, elStyle)

  const targetProps = getTargetProps(elWidth, elHeight)
  let props = getTopLeftProps(anchorProps, targetProps, anchorOrigin, selfOrigin)

  if (absoluteOffset === void 0 || offset === void 0) {
    applyBoundaries(props, anchorProps, targetProps, anchorOrigin, selfOrigin)
  }
  else { // we have touch position or context menu with offset
    const { top, left } = props // cache initial values

    // apply initial boundaries
    applyBoundaries(props, anchorProps, targetProps, anchorOrigin, selfOrigin)

    let hasChanged = false

    // did it flip vertically?
    if (props.top !== top) {
      hasChanged = true
      const offsetY = 2 * offset[ 1 ]
      anchorProps.center = anchorProps.top -= offsetY
      anchorProps.bottom -= offsetY + 2
    }

    // did it flip horizontally?
    if (props.left !== left) {
      hasChanged = true
      const offsetX = 2 * offset[ 0 ]
      anchorProps.middle = anchorProps.left -= offsetX
      anchorProps.right -= offsetX + 2
    }

    if (hasChanged === true) {
      // re-calculate props with the new anchor
      props = getTopLeftProps(anchorProps, targetProps, anchorOrigin, selfOrigin)

      // and re-apply boundaries
      applyBoundaries(props, anchorProps, targetProps, anchorOrigin, selfOrigin)
    }
  }

  elStyle = {
    top: props.top + 'px',
    left: props.left + 'px'
  }

  if (props.maxHeight !== void 0) {
    elStyle.maxHeight = props.maxHeight + 'px'

    if (anchorProps.height > props.maxHeight) {
      elStyle.minHeight = elStyle.maxHeight
    }
  }
  if (props.maxWidth !== void 0) {
    elStyle.maxWidth = props.maxWidth + 'px'

    if (anchorProps.width > props.maxWidth) {
      elStyle.minWidth = elStyle.maxWidth
    }
  }

  Object.assign(targetEl.style, elStyle)

  // restore scroll position
  if (targetEl.scrollTop !== scrollTop) {
    targetEl.scrollTop = scrollTop
  }
  if (targetEl.scrollLeft !== scrollLeft) {
    targetEl.scrollLeft = scrollLeft
  }
}

function applyBoundaries (props, anchorProps, targetProps, anchorOrigin, selfOrigin) {
  const
    currentHeight = targetProps.bottom,
    currentWidth = targetProps.right,
    margin = getScrollbarWidth(),
    innerHeight = window.innerHeight - margin,
    innerWidth = document.body.clientWidth

  if (props.top < 0 || props.top + currentHeight > innerHeight) {
    if (selfOrigin.vertical === 'center') {
      props.top = anchorProps[ anchorOrigin.vertical ] > innerHeight / 2
        ? Math.max(0, innerHeight - currentHeight)
        : 0
      props.maxHeight = Math.min(currentHeight, innerHeight)
    }
    else if (anchorProps[ anchorOrigin.vertical ] > innerHeight / 2) {
      const anchorY = Math.min(
        innerHeight,
        anchorOrigin.vertical === 'center'
          ? anchorProps.center
          : (anchorOrigin.vertical === selfOrigin.vertical ? anchorProps.bottom : anchorProps.top)
      )
      props.maxHeight = Math.min(currentHeight, anchorY)
      props.top = Math.max(0, anchorY - currentHeight)
    }
    else {
      props.top = Math.max(0, anchorOrigin.vertical === 'center'
        ? anchorProps.center
        : (anchorOrigin.vertical === selfOrigin.vertical ? anchorProps.top : anchorProps.bottom)
      )
      props.maxHeight = Math.min(currentHeight, innerHeight - props.top)
    }
  }

  if (props.left < 0 || props.left + currentWidth > innerWidth) {
    props.maxWidth = Math.min(currentWidth, innerWidth)
    if (selfOrigin.horizontal === 'middle') {
      props.left = anchorProps[ anchorOrigin.horizontal ] > innerWidth / 2
        ? Math.max(0, innerWidth - currentWidth)
        : 0
    }
    else if (anchorProps[ anchorOrigin.horizontal ] > innerWidth / 2) {
      const anchorX = Math.min(
        innerWidth,
        anchorOrigin.horizontal === 'middle'
          ? anchorProps.middle
          : (anchorOrigin.horizontal === selfOrigin.horizontal ? anchorProps.right : anchorProps.left)
      )
      props.maxWidth = Math.min(currentWidth, anchorX)
      props.left = Math.max(0, anchorX - props.maxWidth)
    }
    else {
      props.left = Math.max(0, anchorOrigin.horizontal === 'middle'
        ? anchorProps.middle
        : (anchorOrigin.horizontal === selfOrigin.horizontal ? anchorProps.left : anchorProps.right)
      )
      props.maxWidth = Math.min(currentWidth, innerWidth - props.left)
    }
  }
}