optimize for large files

app/javascript/template_builder/document.vue

@@ -56,8 +56,26 @@ export default {
     }
   },
   computed: {
+    numberOfPages () {
+      return this.document.metadata?.pdf?.number_of_pages || this.document.preview_images.length
+    },
     sortedPreviewImages () {
-      return [...this.document.preview_images].sort((a, b) => parseInt(a.filename) - parseInt(b.filename))
+      const lazyloadMetadata = this.document.preview_images[this.document.preview_images.length - 1].metadata
+
+      return [...Array(this.numberOfPages).keys()].map((i) => {
+        return this.previewImagesIndex[i] || {
+          metadata: lazyloadMetadata,
+          id: Math.random().toString(),
+          url: `/preview/${this.document.uuid}/${i}.jpg`
+        }
+      })
+    },
+    previewImagesIndex () {
+      return this.document.preview_images.reduce((acc, e) => {
+        acc[parseInt(e.filename)] = e
+
+        return acc
+      }, {})
     }
   },
   beforeUpdate () {

app/javascript/template_builder/page.vue

@@ -5,11 +5,12 @@
   >
     <img
       ref="image"
+      loading="lazy"
       :src="image.url"
       :width="width"
-      class="border rounded mb-4"
       :height="height"
-      loading="lazy"
+      class="border rounded mb-4"
+      @load="onImageLoad"
     >
     <div
       class="top-0 bottom-0 left-0 right-0 absolute"
@@ -117,6 +118,10 @@ export default {
     this.areaRefs = []
   },
   methods: {
+    onImageLoad (e) {
+      e.target.setAttribute('width', e.target.naturalWidth)
+      e.target.setAttribute('height', e.target.naturalHeight)
+    },
     setAreaRefs (el) {
       if (el) {
         this.areaRefs.push(el)

app/javascript/template_builder/preview.vue

@@ -114,7 +114,7 @@ export default {
   emits: ['scroll-to', 'change', 'remove', 'up', 'down', 'replace'],
   computed: {
     previewImage () {
-      return this.document.preview_images[0]
+      return [...this.document.preview_images].sort((a, b) => parseInt(a.filename) - parseInt(b.filename))[0]
     }
   },
   mounted () {