tldraw/hooks/useZoomEvents.ts
2021-05-13 09:34:56 +01:00

69 lines
1.6 KiB
TypeScript

import React, { useEffect, useRef } from "react"
import state from "state"
import inputs from "state/inputs"
import * as vec from "utils/vec"
/**
* Capture zoom gestures (pinches, wheels and pans) and send to the state.
* @param ref
* @returns
*/
export default function useZoomEvents(
ref: React.MutableRefObject<SVGSVGElement>
) {
const rTouchDist = useRef(0)
useEffect(() => {
const element = ref.current
if (!element) return
function handleWheel(e: WheelEvent) {
e.preventDefault()
if (e.ctrlKey) {
state.send("ZOOMED_CAMERA", {
delta: e.deltaY,
...inputs.wheel(e),
})
return
}
state.send("PANNED_CAMERA", {
delta: [e.deltaX, e.deltaY],
...inputs.wheel(e),
})
}
function handleTouchMove(e: TouchEvent) {
e.preventDefault()
if (e.touches.length === 2) {
const { clientX: x0, clientY: y0 } = e.touches[0]
const { clientX: x1, clientY: y1 } = e.touches[1]
const dist = vec.dist([x0, y0], [x1, y1])
const point = vec.med([x0, y0], [x1, y1])
state.send("WHEELED", {
delta: dist - rTouchDist.current,
point,
})
rTouchDist.current = dist
}
}
element.addEventListener("wheel", handleWheel)
element.addEventListener("touchstart", handleTouchMove)
element.addEventListener("touchmove", handleTouchMove)
return () => {
element.removeEventListener("wheel", handleWheel)
element.removeEventListener("touchstart", handleTouchMove)
element.removeEventListener("touchmove", handleTouchMove)
}
}, [ref])
return {}
}