feat: add custom background image with frosted glass effect

- Add background settings (enabled, url, imageData, blur, opacity) to settings.js
- Add watchSettings same-tab reactivity via custom DOM event dispatch
- Create BackgroundSettingsCard.vue with URL input, file upload, sliders, preview
- Apply background layer in App.vue with blur filter and dark overlay
- Add background settings tab to settings.vue navigation

Agent-Logs-Url: https://github.com/ZeroCatDev/Classworks/sessions/6dfae4c0-df49-4612-88b8-9e31287538b0

Co-authored-by: Sunwuyuan <88357633+Sunwuyuan@users.noreply.github.com>

src/App.vue

@@ -1,5 +1,11 @@
 <template>
-  <v-app>
+  <v-app :style="vAppStyle">
+    <!-- 自定义背景层 -->
+    <template v-if="bgEnabled">
+      <div class="app-background-image" :style="bgImageStyle" />
+      <div class="app-background-overlay" :style="bgOverlayStyle" />
+    </template>
+
     <!-- 正常路由 -->
     <router-view v-slot="{ Component, route }">
       <transition mode="out-in" name="md3">
@@ -12,24 +18,71 @@
 </template>
 
 <script setup>
-import { onMounted } from "vue";
+import { ref, computed, onMounted, onUnmounted } from "vue";
 import { useTheme } from "vuetify";
-import { getSetting } from "@/utils/settings";
+import { getSetting, watchSettings } from "@/utils/settings";
 import RateLimitModal from "@/components/RateLimitModal.vue";
 
 const theme = useTheme();
 
+// Background reactive refs
+const bgEnabled = ref(false);
+const bgSrc = ref("");
+const bgBlur = ref(10);
+const bgOpacity = ref(30);
+
+function loadBgSettings() {
+  bgEnabled.value = getSetting("background.enabled") || false;
+  const imageData = getSetting("background.imageData") || "";
+  const url = getSetting("background.url") || "";
+  bgSrc.value = imageData || url;
+  bgBlur.value = getSetting("background.blur") ?? 10;
+  bgOpacity.value = getSetting("background.opacity") ?? 30;
+}
+
+const vAppStyle = computed(() => {
+  if (!bgEnabled.value || !bgSrc.value) return {};
+  return { background: "transparent" };
+});
+
+const bgImageStyle = computed(() => ({
+  backgroundImage: `url(${bgSrc.value})`,
+  backgroundSize: "cover",
+  backgroundPosition: "center",
+  filter: `blur(${bgBlur.value}px)`,
+  // Scale slightly to hide blur edge artifacts
+  transform: "scale(1.05)",
+}));
+
+const bgOverlayStyle = computed(() => ({
+  background: `rgba(0, 0, 0, ${bgOpacity.value / 100})`,
+}));
+
+let unwatchSettings = null;
+
 onMounted(() => {
   // 应用保存的主题设置
   const savedTheme = getSetting("theme.mode");
   theme.global.name.value = savedTheme;
 
+  loadBgSettings();
+
+  unwatchSettings = watchSettings(() => {
+    loadBgSettings();
+    // Reapply theme on settings change too
+    theme.global.name.value = getSetting("theme.mode");
+  });
+
   window.addEventListener('beforeinstallprompt', (e) => {
     e.preventDefault();
     window.deferredPwaPrompt = e;
     window.dispatchEvent(new Event('pwa-prompt-ready'));
   });
 });
+
+onUnmounted(() => {
+  if (unwatchSettings) unwatchSettings();
+});
 </script>
 <style>
 /* 全局样式（从 index.vue 迁移，确保全局可用且仅加载一次） */
@@ -52,4 +105,21 @@ onMounted(() => {
   opacity: 0;
   transform: translateX(-0.5vw);
 }
+
+/* 自定义背景层 */
+.app-background-image,
+.app-background-overlay {
+  position: fixed;
+  top: 0;
+  left: 0;
+  right: 0;
+  bottom: 0;
+  z-index: -1;
+  pointer-events: none;
+}
+
+.app-background-image {
+  transform-origin: center center;
+  will-change: transform, filter;
+}
 </style>

src/components/settings/cards/BackgroundSettingsCard.vue

@@ -0,0 +1,422 @@
+<template>
+  <settings-card border icon="mdi-image" title="背景设置">
+    <v-list>
+      <setting-item :setting-key="'background.enabled'" />
+    </v-list>
+
+    <v-divider class="mb-4" />
+
+    <div class="px-4 pb-4">
+      <!-- 预览区域 -->
+      <div class="preview-area mb-6" :style="previewContainerStyle">
+        <div class="preview-bg" :style="previewBgStyle" />
+        <div class="preview-overlay" :style="previewOverlayStyle" />
+        <div class="preview-text">背景预览</div>
+      </div>
+
+      <!-- 图片来源 -->
+      <div class="d-flex align-center mb-4">
+        <v-icon class="mr-2" color="primary">mdi-image-search</v-icon>
+        <span class="text-subtitle-1 font-weight-bold">图片来源</span>
+      </div>
+
+      <!-- 来源选择 -->
+      <v-btn-toggle
+        v-model="imageSource"
+        color="primary"
+        density="comfortable"
+        class="mb-4"
+        mandatory
+        rounded="xl"
+      >
+        <v-btn value="url" prepend-icon="mdi-link-variant">网络地址</v-btn>
+        <v-btn value="upload" prepend-icon="mdi-upload">本地上传</v-btn>
+      </v-btn-toggle>
+
+      <!-- URL 输入 -->
+      <div v-if="imageSource === 'url'" class="mb-4">
+        <v-text-field
+          v-model="localUrl"
+          label="图片地址"
+          placeholder="https://example.com/background.jpg"
+          variant="outlined"
+          density="compact"
+          prepend-inner-icon="mdi-link"
+          clearable
+          hide-details="auto"
+          :rules="[validateUrl]"
+          @update:model-value="onUrlChange"
+        />
+        <div class="d-flex flex-wrap gap-2 mt-2">
+          <v-chip
+            v-for="preset in urlPresets"
+            :key="preset.label"
+            size="small"
+            variant="tonal"
+            color="primary"
+            class="cursor-pointer"
+            @click="applyPreset(preset.url)"
+          >
+            {{ preset.label }}
+          </v-chip>
+        </div>
+      </div>
+
+      <!-- 本地上传 -->
+      <div v-if="imageSource === 'upload'" class="mb-4">
+        <div
+          class="upload-area rounded-xl pa-6 text-center mb-3"
+          :class="{ 'upload-hover': isDragging }"
+          @dragover.prevent="isDragging = true"
+          @dragleave="isDragging = false"
+          @drop.prevent="handleDrop"
+          @click="triggerFileInput"
+        >
+          <v-icon size="40" color="primary" class="mb-2">mdi-image-plus</v-icon>
+          <div class="text-body-2">点击或拖拽图片到此处上传</div>
+          <div class="text-caption text-medium-emphasis mt-1">支持 JPG、PNG、WebP、GIF（建议小于 2MB）</div>
+          <input
+            ref="fileInput"
+            type="file"
+            accept="image/*"
+            style="display: none"
+            @change="handleFileChange"
+          />
+        </div>
+
+        <v-alert
+          v-if="uploadWarning"
+          type="warning"
+          variant="tonal"
+          density="compact"
+          class="mb-2"
+          icon="mdi-alert"
+        >
+          {{ uploadWarning }}
+        </v-alert>
+
+        <div v-if="localImageData" class="d-flex align-center ga-2">
+          <v-chip color="success" prepend-icon="mdi-check-circle" size="small">
+            已上传本地图片
+          </v-chip>
+          <v-btn
+            size="small"
+            variant="text"
+            color="error"
+            prepend-icon="mdi-delete"
+            @click="clearUploadedImage"
+          >
+            清除
+          </v-btn>
+        </div>
+      </div>
+
+      <v-divider class="my-5" />
+
+      <!-- 毛玻璃效果设置 -->
+      <div class="d-flex align-center mb-4">
+        <v-icon class="mr-2" color="blue">mdi-blur</v-icon>
+        <span class="text-subtitle-1 font-weight-bold">毛玻璃效果</span>
+      </div>
+
+      <div class="mb-4">
+        <div class="d-flex justify-space-between align-center mb-1">
+          <span class="text-body-2 text-medium-emphasis">模糊幅度</span>
+          <span class="text-body-2 font-weight-bold">{{ localBlur }}px</span>
+        </div>
+        <v-slider
+          v-model="localBlur"
+          :min="0"
+          :max="50"
+          :step="1"
+          color="primary"
+          track-color="grey-lighten-3"
+          thumb-label
+          hide-details
+          @update:model-value="onBlurChange"
+        >
+          <template #prepend>
+            <v-icon size="small" color="grey">mdi-blur-off</v-icon>
+          </template>
+          <template #append>
+            <v-icon size="small" color="primary">mdi-blur</v-icon>
+          </template>
+        </v-slider>
+      </div>
+
+      <div class="mb-4">
+        <div class="d-flex justify-space-between align-center mb-1">
+          <span class="text-body-2 text-medium-emphasis">遮罩暗色程度</span>
+          <span class="text-body-2 font-weight-bold">{{ localOpacity }}%</span>
+        </div>
+        <v-slider
+          v-model="localOpacity"
+          :min="0"
+          :max="80"
+          :step="1"
+          color="blue-grey"
+          track-color="grey-lighten-3"
+          thumb-label
+          hide-details
+          @update:model-value="onOpacityChange"
+        >
+          <template #prepend>
+            <v-icon size="small" color="grey">mdi-brightness-7</v-icon>
+          </template>
+          <template #append>
+            <v-icon size="small" color="blue-grey">mdi-brightness-2</v-icon>
+          </template>
+        </v-slider>
+      </div>
+
+      <v-divider class="my-5" />
+
+      <!-- 保存按钮 -->
+      <div class="d-flex justify-end ga-3">
+        <v-btn variant="text" prepend-icon="mdi-restore" @click="resetAll">
+          重置
+        </v-btn>
+        <v-btn
+          color="primary"
+          variant="elevated"
+          prepend-icon="mdi-content-save"
+          :loading="saving"
+          @click="saveAll"
+        >
+          保存设置
+        </v-btn>
+      </div>
+    </div>
+  </settings-card>
+</template>
+
+<script>
+import SettingsCard from '@/components/SettingsCard.vue';
+import SettingItem from '@/components/settings/SettingItem.vue';
+import { getSetting, setSetting, resetSetting } from '@/utils/settings';
+
+const URL_PRESETS = [
+  { label: 'Bing 每日壁纸', url: 'https://bing.img.run/rand_uhd.php' },
+  { label: '随机风景', url: 'https://picsum.photos/1920/1080?random=1' },
+  { label: '随机自然', url: 'https://source.unsplash.com/1920x1080/?nature' },
+];
+
+const MAX_IMAGE_SIZE_MB = 2;
+
+export default {
+  name: 'BackgroundSettingsCard',
+  components: { SettingsCard, SettingItem },
+
+  data() {
+    const imageData = getSetting('background.imageData') || '';
+    const url = getSetting('background.url') || '';
+
+    return {
+      imageSource: imageData ? 'upload' : 'url',
+      localUrl: url,
+      localImageData: imageData,
+      localBlur: getSetting('background.blur') ?? 10,
+      localOpacity: getSetting('background.opacity') ?? 30,
+      isDragging: false,
+      saving: false,
+      uploadWarning: '',
+      urlPresets: URL_PRESETS,
+    };
+  },
+
+  computed: {
+    /** The active image src for preview */
+    activeImageSrc() {
+      if (this.imageSource === 'upload' && this.localImageData) {
+        return this.localImageData;
+      }
+      if (this.imageSource === 'url' && this.localUrl) {
+        return this.localUrl;
+      }
+      return '';
+    },
+
+    previewContainerStyle() {
+      return {
+        position: 'relative',
+        width: '100%',
+        height: '160px',
+        borderRadius: '12px',
+        overflow: 'hidden',
+        border: '1px solid rgba(128,128,128,0.3)',
+      };
+    },
+
+    previewBgStyle() {
+      if (!this.activeImageSrc) {
+        return {
+          position: 'absolute',
+          inset: '0',
+          background: 'linear-gradient(135deg, #667eea 0%, #764ba2 100%)',
+          filter: `blur(${this.localBlur}px)`,
+          transform: 'scale(1.1)',
+        };
+      }
+      return {
+        position: 'absolute',
+        inset: '0',
+        backgroundImage: `url(${this.activeImageSrc})`,
+        backgroundSize: 'cover',
+        backgroundPosition: 'center',
+        filter: `blur(${this.localBlur}px)`,
+        transform: 'scale(1.1)',
+      };
+    },
+
+    previewOverlayStyle() {
+      return {
+        position: 'absolute',
+        inset: '0',
+        background: `rgba(0, 0, 0, ${this.localOpacity / 100})`,
+      };
+    },
+  },
+
+  methods: {
+    validateUrl(val) {
+      if (!val) return true;
+      try {
+        new URL(val);
+        return true;
+      } catch {
+        return '请输入有效的图片地址';
+      }
+    },
+
+    onUrlChange(val) {
+      this.localUrl = val || '';
+    },
+
+    onBlurChange(val) {
+      this.localBlur = val;
+    },
+
+    onOpacityChange(val) {
+      this.localOpacity = val;
+    },
+
+    applyPreset(url) {
+      this.localUrl = url;
+      this.imageSource = 'url';
+    },
+
+    triggerFileInput() {
+      this.$refs.fileInput.click();
+    },
+
+    handleDrop(event) {
+      this.isDragging = false;
+      const file = event.dataTransfer?.files?.[0];
+      if (file) this.processFile(file);
+    },
+
+    handleFileChange(event) {
+      const file = event.target.files?.[0];
+      if (file) this.processFile(file);
+      // Reset input so same file can be re-selected
+      event.target.value = '';
+    },
+
+    processFile(file) {
+      this.uploadWarning = '';
+
+      if (!file.type.startsWith('image/')) {
+        this.uploadWarning = '请选择图片文件';
+        return;
+      }
+
+      const sizeMB = file.size / 1024 / 1024;
+      if (sizeMB > MAX_IMAGE_SIZE_MB) {
+        this.uploadWarning = `图片大小为 ${sizeMB.toFixed(1)}MB，超过 ${MAX_IMAGE_SIZE_MB}MB 建议大小，可能影响性能`;
+      }
+
+      const reader = new FileReader();
+      reader.onload = (e) => {
+        this.localImageData = e.target.result;
+      };
+      reader.readAsDataURL(file);
+    },
+
+    clearUploadedImage() {
+      this.localImageData = '';
+      this.uploadWarning = '';
+    },
+
+    async saveAll() {
+      this.saving = true;
+      try {
+        // Determine which image source to persist
+        if (this.imageSource === 'upload') {
+          setSetting('background.imageData', this.localImageData || '');
+          setSetting('background.url', '');
+        } else {
+          setSetting('background.url', this.localUrl || '');
+          setSetting('background.imageData', '');
+        }
+
+        setSetting('background.blur', this.localBlur);
+        setSetting('background.opacity', this.localOpacity);
+      } finally {
+        this.saving = false;
+      }
+    },
+
+    resetAll() {
+      resetSetting('background.enabled');
+      resetSetting('background.url');
+      resetSetting('background.imageData');
+      resetSetting('background.blur');
+      resetSetting('background.opacity');
+
+      this.localUrl = getSetting('background.url') || '';
+      this.localImageData = getSetting('background.imageData') || '';
+      this.localBlur = getSetting('background.blur') ?? 10;
+      this.localOpacity = getSetting('background.opacity') ?? 30;
+      this.imageSource = 'url';
+      this.uploadWarning = '';
+    },
+  },
+};
+</script>
+
+<style scoped>
+.preview-area {
+  transition: all 0.3s ease;
+}
+
+.preview-text {
+  position: absolute;
+  inset: 0;
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  color: white;
+  font-size: 1.1rem;
+  font-weight: 600;
+  text-shadow: 0 1px 4px rgba(0, 0, 0, 0.5);
+  z-index: 1;
+  pointer-events: none;
+}
+
+.upload-area {
+  border: 2px dashed rgba(128, 128, 128, 0.4);
+  cursor: pointer;
+  transition: all 0.2s ease;
+  background: rgba(128, 128, 128, 0.05);
+}
+
+.upload-area:hover,
+.upload-hover {
+  border-color: rgb(var(--v-theme-primary));
+  background: rgba(var(--v-theme-primary), 0.05);
+}
+
+.gap-2 {
+  gap: 8px;
+}
+</style>

src/pages/settings.vue

@@ -195,6 +195,10 @@
           <homework-template-card border/>
         </v-tabs-window-item>
 
+        <v-tabs-window-item value="background">
+          <background-settings-card border />
+        </v-tabs-window-item>
+
         <v-tabs-window-item value="developer"
         >
           <settings-card border icon="mdi-developer-board" title="开发者选项">
@@ -280,6 +284,7 @@ import KvDatabaseCard from "@/components/settings/cards/KvDatabaseCard.vue";
 import HitokotoSettings from "@/components/HitokotoSettings.vue";
 import NotificationSoundSettings from "@/components/settings/NotificationSoundSettings.vue";
 import NoiseSettingsCard from "@/components/settings/cards/NoiseSettingsCard.vue";
+import BackgroundSettingsCard from "@/components/settings/cards/BackgroundSettingsCard.vue";
 
 export default {
   name: "Settings",
@@ -304,6 +309,7 @@ export default {
     HitokotoSettings,
     NotificationSoundSettings,
     NoiseSettingsCard,
+    BackgroundSettingsCard,
   },
   setup() {
     const {mobile} = useDisplay();
@@ -442,6 +448,12 @@ export default {
           value: "randomPicker",
         },
 
+        {
+          title: "背景",
+          icon: "mdi-image",
+          value: "background",
+        },
+
         {
           title: "开发者",
           icon: "mdi-developer-board",

src/utils/settings.js

@@ -441,6 +441,40 @@ const settingsDefinitions = {
     // 设置应用的主题模式，可选亮色或暗色主题
   },
 
+  // 背景设置
+  "background.enabled": {
+    type: "boolean",
+    default: false,
+    description: "启用自定义背景",
+    icon: "mdi-image",
+  },
+  "background.url": {
+    type: "string",
+    default: "",
+    description: "背景图片地址",
+    icon: "mdi-link",
+  },
+  "background.imageData": {
+    type: "string",
+    default: "",
+    description: "本地背景图片（Base64）",
+    icon: "mdi-image-area",
+  },
+  "background.blur": {
+    type: "number",
+    default: 10,
+    validate: (value) => value >= 0 && value <= 50,
+    description: "毛玻璃模糊幅度（px）",
+    icon: "mdi-blur",
+  },
+  "background.opacity": {
+    type: "number",
+    default: 30,
+    validate: (value) => value >= 0 && value <= 80,
+    description: "遮罩暗色程度（%）",
+    icon: "mdi-circle-half-full",
+  },
+
   // 通知铃声设置
   "notification.singleSound": {
     type: "string",
@@ -674,6 +708,13 @@ class SettingsManagerClass {
       this.saveSettings();
       this.logSettingsChange(key, oldValue, value);
 
+      // 触发同标签页内的设置变化事件
+      if (typeof window !== "undefined") {
+        window.dispatchEvent(new CustomEvent("classworks-settings-changed", {
+          detail: { key, value },
+        }));
+      }
+
       // 为了保持向后兼容，同时更新旧的localStorage键
       const legacyKey = definition.legacyKey;
       if (legacyKey && typeof localStorage !== "undefined") {
@@ -721,6 +762,13 @@ class SettingsManagerClass {
 
     this.settingsCache[key] = definition.default;
     this.saveSettings();
+
+    // 触发同标签页内的设置变化事件
+    if (typeof window !== "undefined") {
+      window.dispatchEvent(new CustomEvent("classworks-settings-changed", {
+        detail: { key, value: definition.default },
+      }));
+    }
   }
 
   /**
@@ -743,15 +791,23 @@ class SettingsManagerClass {
     if (typeof window === "undefined") return () => {
     };
 
-    const handler = (event) => {
+    const storageHandler = (event) => {
       if (event.key === SETTINGS_STORAGE_KEY) {
         this.settingsCache = JSON.parse(event.newValue);
         callback(this.settingsCache);
       }
     };
 
-    window.addEventListener("storage", handler);
+    const customHandler = () => {
-    return () => window.removeEventListener("storage", handler);
+      callback(this.settingsCache);
+    };
+
+    window.addEventListener("storage", storageHandler);
+    window.addEventListener("classworks-settings-changed", customHandler);
+    return () => {
+      window.removeEventListener("storage", storageHandler);
+      window.removeEventListener("classworks-settings-changed", customHandler);
+    };
   }
 
   /**