leafer的Canvas元素改变宽高后，获取imageData很慢

[bgyh2003]

leafer的Canvas元素改变宽高后，获取imageData很慢，要100多毫秒

const { Canvas } = LeaferUI
const canvas = new Canvas({ width: 10000, height: 10000 })

canvas.width = 700
canvas.height = 300

console.time("getImageData")
const imageData = canvas.context.getImageData(0, 0, 700, 300)
console.timeEnd("getImageData") // getImageData: 102.496826171875 ms

原生canvas只需要4毫秒

const canvas = document.createElement("canvas")
canvas.width = 10000
canvas.height = 10000
const ctx = canvas.getContext("2d")

canvas.width = 700
canvas.height = 300

console.time("getImageData")
const imageData = ctx.getImageData(0, 0, 700, 300)
console.timeEnd("getImageData") // getImageData: 3.77783203125 ms

延迟一秒获取，速度就恢复正常了，5-10毫秒，这是为什么呢

const { Canvas } = LeaferUI
const canvas = new Canvas({ width: 10000, height: 10000 })

canvas.width = 700
canvas.height = 300

setTimeout(() => {
  console.time("getImageData")
  const imageData = canvas.context.getImageData(0, 0, 700, 300)
  console.timeEnd("getImageData") // getImageData: 10.425048828125 ms
}, 1000)

因为我需要处理canvas的像素，可能要不断的getImageData，100多毫秒很慢啊，怎样解决呢

[leaferjs]

Canvas 增加 contextSettings.willReadFrequently 配置试试

https://www.leaferjs.com/ui/reference/display/Canvas.html#contextsettings-icanvasrenderingcontext2dsettings

[bgyh2003]

Canvas 增加 contextSettings.willReadFrequently 配置试试

https://www.leaferjs.com/ui/reference/display/Canvas.html#contextsettings-icanvasrenderingcontext2dsettings

不好使，已经用别的方法解决了