ComfyUI_frontend/src/components/common/LazyImage.vue

<template>
  <div
    ref="containerRef"
    class="relative flex size-full items-center justify-center overflow-hidden"
    :class="containerClass"
  >
    <Skeleton
      v-if="!isImageLoaded"
      width="100%"
      height="100%"
      class="absolute inset-0"
    />
    <img
      v-if="cachedSrc"
      ref="imageRef"
      :src="cachedSrc"
      :alt="alt"
      draggable="false"
      :class="imageClass"
      :style="imageStyle"
      @load="onImageLoad"
      @error="onImageError"
    />
    <div
      v-if="hasError"
      class="bg-surface-50 text-muted dark-theme:bg-surface-800 absolute inset-0 flex items-center justify-center"
    >
      <img
        src="/assets/images/default-template.png"
        :alt="alt"
        draggable="false"
        :class="imageClass"
        :style="imageStyle"
      />
    </div>
  </div>
</template>

<script setup lang="ts">
import Skeleton from 'primevue/skeleton'
import { computed, onUnmounted, ref, watch } from 'vue'

import { useIntersectionObserver } from '@/composables/useIntersectionObserver'
import { useMediaCache } from '@/services/mediaCacheService'
import type { ClassValue } from '@/utils/tailwindUtil'

const {
  src,
  alt = '',
  containerClass = '',
  imageClass = '',
  imageStyle,
  rootMargin = '300px'
} = defineProps<{
  src: string
  alt?: string
  containerClass?: ClassValue
  imageClass?: ClassValue
  imageStyle?: Record<string, any>
  rootMargin?: string
}>()

const containerRef = ref<HTMLElement | null>(null)
const imageRef = ref<HTMLImageElement | null>(null)
const isIntersecting = ref(false)
const isImageLoaded = ref(false)
const hasError = ref(false)
const cachedSrc = ref<string | undefined>(undefined)

const { getCachedMedia, acquireUrl, releaseUrl } = useMediaCache()

// Use intersection observer to detect when the image container comes into view
useIntersectionObserver(
  containerRef,
  (entries) => {
    const entry = entries[0]
    isIntersecting.value = entry?.isIntersecting ?? false
  },
  {
    rootMargin,
    threshold: 0.1
  }
)

// Only start loading the image when it's in view
const shouldLoad = computed(() => isIntersecting.value)

watch(
  shouldLoad,
  async (shouldLoadVal) => {
    if (shouldLoadVal && src && !cachedSrc.value && !hasError.value) {
      try {
        const cachedMedia = await getCachedMedia(src)
        if (cachedMedia.error) {
          hasError.value = true
        } else if (cachedMedia.objectUrl) {
          const acquiredUrl = acquireUrl(src)
          cachedSrc.value = acquiredUrl || cachedMedia.objectUrl
        } else {
          cachedSrc.value = src
        }
      } catch (error) {
        console.warn('Failed to load cached media:', error)
        cachedSrc.value = src
      }
    } else if (!shouldLoadVal) {
      if (cachedSrc.value?.startsWith('blob:')) {
        releaseUrl(src)
      }
      // Hide image when out of view
      isImageLoaded.value = false
      cachedSrc.value = undefined
      hasError.value = false
    }
  },
  { immediate: true }
)

const onImageLoad = () => {
  isImageLoaded.value = true
  hasError.value = false
}

const onImageError = () => {
  hasError.value = true
  isImageLoaded.value = false
}

onUnmounted(() => {
  if (cachedSrc.value?.startsWith('blob:')) {
    releaseUrl(src)
  }
})
</script>