图片失败后继续加载阅读页并支持单图重试

src/components/OnlineReader.vue

@@ -1,5 +1,6 @@
 <script setup>
-import {computed, ref, watch} from "vue";
+import {computed, ref, watch, onBeforeUnmount} from "vue";
+import {startImages, settleImage, retryImage} from "../utils/progressiveImages.js";
 import store from "../store/index.js";
 let onlineReadingScrollbar = ref()
 let links = ref()
@@ -7,13 +8,12 @@ let index = ref(0)  //下标
 let page = ref(0)   //页数  下标+1=页数  用于跳转
 
 let imagesForLoading = ref([])
-let loadIndex = ref(0)
 let isReading = ref(false)
 
 let max = ref(0)
 let current_page = 0
 let lengthPerPage = computed(() => {
-  return store.state.lengthPerPage
+  return Math.max(1, Number(store.state.lengthPerPage) || 10)
 })
 let readingGallery = computed(() => {
   return store.state.readingGallery
@@ -36,28 +36,34 @@ function alterPage(){
   }
   index.value = 0
   page.value = 1
-  loadIndex.value = 0
-  imagesForLoading.value.splice(0)
-  loadImage()
+  imagesForLoading.value = startImages(links.value)
 }
 
 //跳转到对应页数
 function jump(targetIndex){
+  if(targetIndex < 0 || targetIndex >= Math.ceil(readingGallery.value.images.length / lengthPerPage.value)) return
+  clearPageSwitchTimer()
   links.value = readingGallery.value.images.slice(targetIndex * lengthPerPage.value, (targetIndex + 1) * lengthPerPage.value)
   index.value = targetIndex
   page.value = targetIndex + 1
-  imagesForLoading.value.splice(0)
-  loadIndex.value = 0
-  loadImage()
+  imagesForLoading.value = startImages(links.value)
   onlineReadingScrollbar.value.setScrollTop(0)
 }
 
-function loadImage(){
-  if(loadIndex.value < links.value.length)
-    imagesForLoading.value.push(links.value[loadIndex.value++])
+function imageResult(item, failed = false){
+  settleImage(imagesForLoading.value, links.value, item, failed)
 }
 
+let pageSwitchTimer
+function clearPageSwitchTimer(){
+  clearInterval(pageSwitchTimer)
+  pageSwitchTimer = undefined
+}
+onBeforeUnmount(clearPageSwitchTimer)
+
 function closeDialog(){
+  clearPageSwitchTimer()
+  imagesForLoading.value = []
   onlineReadingScrollbar.value.setScrollTop(0)
   isReading.value = false
   store.commit("_closeReader")
@@ -70,16 +76,16 @@ function switch_page(target_page){
     jump(index.value - 1)
     onlineReadingScrollbar.value.setScrollTop(onlineReadingScrollbar.value.wrapRef.scrollHeight)
     let top = 0
-    let timer = setInterval(() => {
+    pageSwitchTimer = setInterval(() => {
       if(onlineReadingScrollbar.value.scrollTop === top){
-        clearInterval(timer)
+        clearPageSwitchTimer()
         document.querySelector("div.el-scrollbar__wrap.el-scrollbar__wrap--hidden-default > div > div:last-child > img").click()
       }
       top = onlineReadingScrollbar.value.scrollTop
       onlineReadingScrollbar.value.setScrollTop(onlineReadingScrollbar.value.wrapRef.scrollHeight)
     }, 100)
   //下一页
-  }else if(target_page === 0 && current_page === lengthPerPage.value - 1 && index.value < max.value){
+  }else if(target_page === 0 && current_page === lengthPerPage.value - 1 && index.value < max.value - 1){
     jump(index.value + 1)
     current_page = 0
     document.querySelector("div.el-scrollbar__wrap.el-scrollbar__wrap--hidden-default > div > div:nth-child(1) > img").click()
@@ -105,9 +111,10 @@ function set_current_page(page){
       </div>
     </template>
     <el-scrollbar height="75vh" ref="onlineReadingScrollbar">
-      <div v-for="(link, i) in imagesForLoading" style="display: inline-block; text-align: center; min-height: 300px">
-        <el-image :src="link" :style="{'width': '66vw', 'background-color': 'gary'}"
-                  :preview-src-list="links" :initial-index="i" @switch="switch_page" @show="set_current_page(i)" loading="lazy" @load="loadImage"/><br>
+      <div v-for="(item, i) in imagesForLoading" :key="item.url + '-' + item.attempt" style="display: inline-block; text-align: center; min-height: 300px">
+        <el-image :src="item.src" :style="{'width': '66vw', 'background-color': 'gary'}"
+                  :preview-src-list="links" :initial-index="i" @switch="switch_page" @show="set_current_page(i)" loading="lazy" @load="imageResult(item)" @error="imageResult(item, true)"/>
+        <div v-if="item.failed" role="alert">图片加载失败 <el-button size="small" @click="retryImage(item)">重试</el-button></div><br>
         {{lengthPerPage * index + i + 1}}
       </div>
     </el-scrollbar>

src/utils/progressiveImages.js

@@ -0,0 +1,23 @@
+function imageItem(url, index) {
+    return {url, src: url, index, attempt: 0, failed: false, settled: false}
+}
+
+export function startImages(urls) {
+    return urls.length ? [imageItem(urls[0], 0)] : []
+}
+
+export function settleImage(items, urls, item, failed = false) {
+    // Ignore events from images removed by a page change or dialog close.
+    if (!items.includes(item)) return
+    item.failed = failed
+    if (item.settled) return
+    item.settled = true
+    if (items.length < urls.length)
+        items.push(imageItem(urls[items.length], items.length))
+}
+
+export function retryImage(item) {
+    item.failed = false
+    item.attempt++
+    item.src = item.url + (item.url.includes('?') ? '&' : '?') + 'retry=' + item.attempt
+}

tests/progressiveImages.test.mjs

@@ -0,0 +1,33 @@
+import test from 'node:test'
+import assert from 'node:assert/strict'
+import {startImages, settleImage, retryImage} from '../src/utils/progressiveImages.js'
+
+test('a failed image does not prevent later pages from loading', () => {
+    const urls = ['first', 'second', 'third']
+    const items = startImages(urls)
+    settleImage(items, urls, items[0], true)
+    assert.equal(items[0].failed, true)
+    assert.equal(items[1].url, 'second')
+    settleImage(items, urls, items[1])
+    assert.equal(items[2].url, 'third')
+})
+
+test('retry does not append a duplicate page and bypasses a failed URL cache', () => {
+    const urls = ['first?gid=1', 'second', 'third']
+    const items = startImages(urls)
+    settleImage(items, urls, items[0], true)
+    retryImage(items[0])
+    assert.equal(items[0].src, 'first?gid=1&retry=1')
+    settleImage(items, urls, items[0])
+    assert.equal(items.length, 2)
+    assert.equal(items[0].failed, false)
+})
+
+test('late image events cannot append content after changing pages', () => {
+    const old = startImages(['old'])[0]
+    const urls = ['new', 'next']
+    const items = startImages(urls)
+    settleImage(items, urls, old)
+    assert.equal(items.length, 1)
+    assert.deepEqual(startImages([]), [])
+})