Function convertImage

app/javascript/elements/convert_upload.js:1–29

(sourceFile, targetType, quality)

export function convertImage (sourceFile, targetType, quality) {
  return new Promise((resolve, reject) => {
    const reader = new FileReader()

    reader.onload = function (event) {
      const img = new Image()

      img.onload = function () {
        const canvas = document.createElement('canvas')
        const ctx = canvas.getContext('2d')

        canvas.width = img.width
        canvas.height = img.height
        ctx.drawImage(img, 0, 0)
        canvas.toBlob(function (blob) {
          const ext = targetType === 'image/jpeg' ? '.jpg' : '.png'
          const newFile = new File([blob], sourceFile.name.replace(/\.\w+$/, ext), { type: targetType })
          resolve(newFile)
        }, targetType, quality)
      }

      img.onerror = () => reject(new Error(`browser cannot decode ${sourceFile.type || sourceFile.name}`))

      img.src = event.target.result
    }
    reader.onerror = reject
    reader.readAsDataURL(sourceFile)
  })
}

export async function convertImagesInInput (input) {
  if (!input.files || input.files.length === 0) return