convert images on upload

app/javascript/template_builder/upload.vue

@@ -168,6 +168,65 @@
 <script>
 import { IconUpload, IconInnerShadowTop, IconChevronDown, IconBrandGoogleDrive } from '@tabler/icons-vue'
 
+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)
+  })
+}
+
+async function convertImagesInInput (input) {
+  if (!input.files || input.files.length === 0) return
+
+  const dt = new DataTransfer()
+  let didConvert = false
+
+  for (const file of Array.from(input.files)) {
+    let converted = file
+
+    try {
+      if (['image/bmp', 'image/vnd.microsoft.icon', 'image/svg+xml'].includes(file.type)) {
+        converted = await convertImage(file, 'image/png')
+        didConvert = true
+      } else if (['image/heic', 'image/heif', 'image/heic-sequence', 'image/heif-sequence', 'image/avif', 'image/avif-sequence'].includes(file.type)) {
+        converted = await convertImage(file, 'image/jpeg', 0.9)
+        didConvert = true
+      }
+    } catch (e) {
+      alert(e.message)
+    }
+
+    dt.items.add(converted)
+  }
+
+  if (didConvert) {
+    input.files = dt.files
+  }
+}
+
 export default {
   name: 'DocumentsUpload',
   components: {
@@ -282,6 +341,10 @@ export default {
     async upload ({ path } = {}) {
       this.isLoading = true
 
+      if (this.$refs.input) {
+        await convertImagesInInput(this.$refs.input)
+      }
+
       return this.baseFetch(path || this.uploadUrl, {
         method: 'POST',
         headers: { Accept: 'application/json' },