Add background image upload and real-time layer editing

- Background layer: color picker (real-time) + image upload + clear
- Image preview shows in sidebar after upload
- Uploaded image scales to fill the card dimensions
- All layer properties now update canvas in real-time (no apply button needed)
- Border: color + thickness slider real-time
- Text: font size slider real-time
- Click canvas objects to select layer and sync properties

frontend/src/views/Editor.vue

@@ -37,21 +37,33 @@
         </div>
 
         <h3 style="margin: 25px 0 12px 0; font-size: 14px; color: #888;">属性编辑</h3>
-        <div v-if="activeLayer === 'bg'" style="display: flex; flex-direction: column; gap: 8px;">
-          <label style="font-size: 12px; color: #aaa;">背景颜色</label>
-          <input v-model="bgColor" type="color" @input="updateBgColor" style="width: 100%; height: 30px; border: none; border-radius: 4px; cursor: pointer;">
-          <button @click="applyBgColor" style="padding: 6px 12px; background: #e94560; color: white; border: none; border-radius: 4px; cursor: pointer; font-size: 12px;">应用背景色</button>
+        <div v-if="activeLayer === 'bg'" style="display: flex; flex-direction: column; gap: 10px;">
+          <label style="font-size: 12px; color: #aaa;">背景颜色（实时预览）</label>
+          <input v-model="bgColor" type="color" @input="onBgColorChange" style="width: 100%; height: 32px; border: none; border-radius: 4px; cursor: pointer;">
+          
+          <div style="border-top: 1px solid #333; margin: 4px 0;"></div>
+          
+          <label style="font-size: 12px; color: #aaa;">上传背景图片</label>
+          <input ref="bgFileInput" type="file" accept="image/*" @change="onBgImageUpload" style="display: none;">
+          <div style="display: flex; gap: 8px; flex-wrap: wrap;">
+            <button @click="triggerBgUpload" style="flex: 1; padding: 8px 12px; background: #16213e; color: #aaa; border: 1px solid #444; border-radius: 4px; cursor: pointer; font-size: 12px; white-space: nowrap;">选择图片</button>
+            <button v-if="bgImageUrl" @click="clearBgImage" style="padding: 8px 12px; background: #e94560; color: white; border: none; border-radius: 4px; cursor: pointer; font-size: 12px;">清除</button>
+          </div>
+          
+          <div v-if="bgImageUrl" style="margin-top: 4px;">
+            <div style="font-size: 10px; color: #666; margin-bottom: 4px;">图片预览:</div>
+            <img :src="bgImageUrl" style="width: 100%; max-height: 100px; object-fit: contain; border-radius: 4px; border: 1px solid #333;">
+          </div>
         </div>
         <div v-if="activeLayer === 'border'" style="display: flex; flex-direction: column; gap: 8px;">
-          <label style="font-size: 12px; color: #aaa;">边框颜色</label>
-          <input v-model="borderColor" type="color" @input="updateBorderColor" style="width: 100%; height: 30px; border: none; border-radius: 4px; cursor: pointer;">
+          <label style="font-size: 12px; color: #aaa;">边框颜色（实时）</label>
+          <input v-model="borderColor" type="color" @input="onBorderColorChange" style="width: 100%; height: 32px; border: none; border-radius: 4px; cursor: pointer;">
           <label style="font-size: 12px; color: #aaa;">边框粗细: {{ borderWidth }}px</label>
-          <input v-model="borderWidth" type="range" min="0" max="10" step="1" @input="applyBorder" style="width: 100%; cursor: pointer;">
-          <button @click="applyBorder" style="padding: 6px 12px; background: #e94560; color: white; border: none; border-radius: 4px; cursor: pointer; font-size: 12px;">应用边框</button>
+          <input v-model="borderWidth" type="range" min="0" max="20" step="1" @input="onBorderChange" style="width: 100%; cursor: pointer;">
         </div>
         <div v-if="activeLayer === 'text'" style="display: flex; flex-direction: column; gap: 8px;">
-          <label style="font-size: 12px; color: #aaa;">字体大小: {{ textSize }}px</label>
-          <input v-model="textSize" type="range" min="12" max="120" step="2" @input="applyTextStyle" style="width: 100%; cursor: pointer;">
+          <label style="font-size: 12px; color: #aaa;">字体大小（实时）: {{ textSize }}px</label>
+          <input v-model="textSize" type="range" min="12" max="120" step="2" @input="onTextSizeChange" style="width: 100%; cursor: pointer;">
         </div>
         <div v-if="!['bg','border','text','pattern'].includes(activeLayer)" style="color: #888; font-size: 12px; padding: 10px;">
           选中画布上的对象查看属性
@@ -78,7 +90,7 @@
 <script setup>
 import { ref, onMounted, computed, nextTick } from 'vue'
 import { useRoute, useRouter } from 'vue-router'
-import { Canvas, FabricText, Rect } from 'fabric'
+import { Canvas, FabricText, Rect, FabricImage } from 'fabric'
 import axios from 'axios'
 
 const route = useRoute()
@@ -107,39 +119,87 @@ const currentCards = computed(() => {
 })
 
 const layers = ref([
-  { id: 'bg', name: '背景层', visible: true, zIndex: 0, fillColor: '#ffffff' },
+  { id: 'bg', name: '背景层', visible: true, zIndex: 0, fillColor: '#ffffff', imageData: null },
   { id: 'border', name: '边框层', visible: true, zIndex: 1, strokeColor: '#333333', strokeWidth: 2 },
   { id: 'pattern', name: '图案层', visible: true, zIndex: 2 },
   { id: 'text', name: '文字层', visible: true, zIndex: 3, textSize: 32 }
 ])
 
 const bgColor = ref('#ffffff')
+const bgImageUrl = ref(null)
 const borderColor = ref('#333333')
 const borderWidth = ref(2)
 const textSize = ref(32)
 
-function updateBgColor() {
-  const l = layers.value.find(x => x.id === 'bg')
-  if (l) l.fillColor = bgColor.value
+const bgFileInput = ref(null)
+
+function triggerBgUpload() {
+  bgFileInput.value?.click()
 }
 
-function applyBgColor() {
-  updateBgColor()
+function onBgImageUpload(e) {
+  const file = e.target.files[0]
+  if (!file) return
+  const reader = new FileReader()
+  reader.onload = (ev) => {
+    bgImageUrl.value = ev.target.result
+    const l = layers.value.find(x => x.id === 'bg')
+    if (l) l.imageData = ev.target.result
+    drawCard()
+  }
+  reader.readAsDataURL(file)
+}
+
+function clearBgImage() {
+  bgImageUrl.value = null
+  const l = layers.value.find(x => x.id === 'bg')
+  if (l) l.imageData = null
   drawCard()
 }
 
-function applyBorder() {
+function onBgColorChange() {
+  const l = layers.value.find(x => x.id === 'bg')
+  if (l) l.fillColor = bgColor.value
+  drawCard()
+}
+
+function toggleLayer(layer) {
+  activeLayer.value = layer.id
+  layer.visible = !layer.visible
+  syncLayerProps()
+  drawCard()
+}
+
+function syncLayerProps() {
+  const bgLayer = layers.value.find(x => x.id === 'bg')
+  if (bgLayer) {
+    bgColor.value = bgLayer.fillColor
+    bgImageUrl.value = bgLayer.imageData
+  }
+  const bLayer = layers.value.find(x => x.id === 'border')
+  if (bLayer) {
+    borderColor.value = bLayer.strokeColor
+    borderWidth.value = bLayer.strokeWidth
+  }
+  const tLayer = layers.value.find(x => x.id === 'text')
+  if (tLayer) {
+    textSize.value = tLayer.textSize
+  }
+}
+
+function onBorderColorChange() {
+  const l = layers.value.find(x => x.id === 'border')
+  if (l) l.strokeColor = borderColor.value
+  drawCard()
+}
+
+function onBorderChange() {
   const l = layers.value.find(x => x.id === 'border')
   if (l) { l.strokeColor = borderColor.value; l.strokeWidth = parseInt(borderWidth.value) }
   drawCard()
 }
 
-function updateBorderColor() {
-  const l = layers.value.find(x => x.id === 'border')
-  if (l) l.strokeColor = borderColor.value
-}
-
-function applyTextStyle() {
+function onTextSizeChange() {
   const l = layers.value.find(x => x.id === 'text')
   if (l) l.textSize = parseInt(textSize.value)
   drawCard()
@@ -153,12 +213,6 @@ function isRed(suit) {
   return suit === 'heart' || suit === 'diamond'
 }
 
-function toggleLayer(layer) {
-  activeLayer.value = layer.id
-  layer.visible = !layer.visible
-  drawCard()
-}
-
 function moveLayer(layer, delta) {
   const newZ = layer.zIndex + delta
   const swapped = layers.value.find(l => l.zIndex === newZ)
@@ -196,6 +250,7 @@ function initCanvas() {
     const obj = e.selected[0]
     if (obj && obj.layerId) {
       activeLayer.value = obj.layerId
+      syncLayerProps()
     }
   })
 
@@ -203,6 +258,7 @@ function initCanvas() {
     const obj = e.selected[0]
     if (obj && obj.layerId) {
       activeLayer.value = obj.layerId
+      syncLayerProps()
     }
   })
 
@@ -227,9 +283,22 @@ function drawCard() {
     if (!layer.visible) continue
 
     if (layer.id === 'bg') {
-      const bg = new Rect({ left: 0, top: 0, width: cardW, height: cardH, fill: layer.fillColor || '#ffffff', selectable: true, hasControls: false, lockMovementX: true, lockMovementY: true, stroke: 'transparent', strokeWidth: 0 })
-      bg.layerId = 'bg'
-      c.add(bg)
+      if (layer.imageData) {
+        const bgImg = new Image()
+        bgImg.crossOrigin = 'anonymous'
+        bgImg.onload = () => {
+          const fImg = new FabricImage(bgImg, { left: 0, top: 0, selectable: true, hasControls: false, lockMovementX: true, lockMovementY: true })
+          fImg.scaleX = cardW / bgImg.width
+          fImg.scaleY = cardH / bgImg.height
+          fImg.layerId = 'bg'
+          c.insertAt(0, fImg)
+          c.renderAll()
+        }
+        bgImg.src = layer.imageData
+      }
+      const bgRect = new Rect({ left: 0, top: 0, width: cardW, height: cardH, fill: layer.imageData ? 'transparent' : (layer.fillColor || '#ffffff'), selectable: true, hasControls: false, lockMovementX: true, lockMovementY: true, stroke: 'transparent', strokeWidth: 0 })
+      bgRect.layerId = 'bg'
+      c.add(bgRect)
     }
 
     if (layer.id === 'border') {