tldraw/hooks/usePageShapes.ts
2021-06-29 13:00:59 +01:00

50 lines
1.3 KiB
TypeScript

import { useEffect } from 'react'
import state, { useSelector } from 'state'
import { getShapeUtils } from 'state/shape-utils'
import { PageState, Bounds } from 'types'
import {
boundsCollide,
boundsContain,
debounce,
deepCompareArrays,
} from 'utils'
import tld from 'utils/tld'
const viewportCache = new WeakMap<PageState, Bounds>()
export default function usePageShapes(): string[] {
// Reset the viewport cache when the window resizes
useEffect(() => {
const handleResize = debounce(() => state.send('RESIZED_WINDOW'), 32)
window.addEventListener('resize', handleResize)
return () => {
window.removeEventListener('resize', handleResize)
}
}, [])
// Get the shapes that fit into the current window
const visiblePageShapeIds = useSelector((s) => {
const pageState = tld.getPageState(s.data)
if (!viewportCache.has(pageState)) {
const viewport = tld.getViewport(s.data)
viewportCache.set(pageState, viewport)
}
const viewport = viewportCache.get(pageState)
return s.values.currentShapes
.filter((shape) => {
const shapeBounds = getShapeUtils(shape).getBounds(shape)
return (
boundsContain(viewport, shapeBounds) ||
boundsCollide(viewport, shapeBounds)
)
})
.map((shape) => shape.id)
}, deepCompareArrays)
return visiblePageShapeIds
}