feat: 预设素材库 - 4 套主题 × 4 张图 = 16 张 PNG

主题：classical 古典宫廷（王子/皇后/国王/小丑）
      modern    现代人物（小孩/女青年/男青年/小丑鱼）
      astronomy 天文（星星/月亮/太阳/黑洞）
      minimal   简笔符号（圆点/♀/♂/叉）

改动：
- 新增 LibraryAsset 模型（全局素材库，theme_id/role/asset_id 索引）
- 新增 seed_library 管理命令，用 Pillow 画 16 张 PNG 素材
- 新增 /api/projects/library/ 列表 API
- 新增 /api/projects/{pid}/library/{id}/apply/ 应用 API
  把预设素材复制到 projects/<pid>/joker 或 face_card 下，作为该牌位的素材
- AssetPanel 加 tab 切换：「我的素材」+「预设主题」，主题可筛选、点击套用到当前牌
- 修复 generate_card_png 的 joker asset 匹配 bug：which 应该是 card_key（含前缀）才能匹配 asset_key

设计要点：
- 预设素材只画上半身（y=0~150），下半留空，让系统的'自动对称'流水线正确工作
- 预设素材 PNG 200×300，深色描边 + 半透明浅色填充，在任意牌面背景上叠加都清晰

backend/apps/exports/utils.py

@@ -430,9 +430,10 @@ def generate_card_png(project, card_key, resolution='standard'):
 
     # 3. 主体内容
     if card_key.startswith('joker-'):
+        # which 是去掉前缀的 'big'/'small'，但 asset_key 含 'joker-' 前缀
         which = card_key.split('-', 1)[1]  # big / small
         asset = None
-        for a in project.assets.filter(asset_type='joker', asset_key=which):
+        for a in project.assets.filter(asset_type='joker', asset_key=card_key):
             p = os.path.join('media', a.file_path) if a.file_path else None
             asset = load_image_safe(p) if p else None
             break

backend/apps/projects/management/commands/seed_library.py

@@ -0,0 +1,428 @@
+"""
+初始化预设素材库：用 Pillow 直接画 PNG（200×300），存到 media/library/，并写入 LibraryAsset 表。
+
+主题（4 套 × 4 张 = 16 张）：
+  classical  古典宫廷：王子/皇后/国王/宫廷小丑
+  modern     现代人物：小孩/女青年/男青年/小丑鱼
+  astronomy  天文：    星星/月亮/太阳/黑洞
+  minimal    简笔符号：圆点/♀/♂/叉
+
+风格：深色描边 4px + 半透明浅色填充，便于在任意牌面背景上叠加。
+"""
+import os
+import math
+from django.core.management.base import BaseCommand
+from django.conf import settings
+from apps.projects.models import LibraryAsset
+from PIL import Image, ImageDraw
+
+
+W, H = 200, 300
+STROKE = (26, 26, 26, 255)
+STROKE_W = 4
+# 关键：素材主体只画在 y=20~200（上半身），y=200~300 留空。
+# 因为后端会把整图 fill 到 body 区域，再切上半 + 翻转下半拼成上下对称，
+# 所以素材本身只需要"上半身"，下半由系统自动翻转生成。
+BODY_TOP = 20
+BODY_BOTTOM = 200
+
+
+def new_canvas():
+    img = Image.new('RGBA', (W, H), (255, 255, 255, 0))
+    return img, ImageDraw.Draw(img)
+
+
+def shift_up(img, dy=-30):
+    """把图整体上移 dy 像素，下方留空。
+    因为素材只需要画上半身，下半由系统对称生成。"""
+    out = Image.new('RGBA', (W, H), (0, 0, 0, 0))
+    out.paste(img, (0, dy), img)
+    return out
+
+
+def crop_to_upper(img):
+    """把图裁到 y=0~150 区域（只保留上半身），下面 150px 留空。
+    后端 fill 整图后切上下半 = 上半=原图上半(0~150)，下半=原图下半(150~300 留空)
+    → 翻转下半也是空白 → 整张牌上半身 + 空白（不会有奇怪的下半）"""
+    out = Image.new('RGBA', (W, H), (0, 0, 0, 0))
+    upper = img.crop((0, 0, W, 150))
+    out.paste(upper, (0, 0), upper)
+    return out
+
+
+# ----------------- 古典宫廷 -----------------
+def classical_prince():
+    img, d = new_canvas()
+    # 头发
+    d.polygon([(50, 110), (55, 130), (145, 130), (150, 110), (145, 100), (55, 100)],
+              fill=(180, 140, 80, 100), outline=STROKE, width=STROKE_W)
+    # 脸
+    d.ellipse((60, 100, 140, 180), fill=(255, 224, 189, 150), outline=STROKE, width=STROKE_W)
+    # 眼睛
+    d.ellipse((85, 134, 91, 140), fill=STROKE)
+    d.ellipse((109, 134, 115, 140), fill=STROKE)
+    # 嘴
+    d.arc((90, 148, 110, 162), start=0, end=180, fill=STROKE, width=3)
+    # 小皇冠
+    d.polygon([(70, 78), (78, 60), (86, 75), (100, 55), (114, 75), (122, 60), (130, 78)],
+              fill=(255, 220, 80, 130), outline=STROKE, width=STROKE_W)
+    d.ellipse((96, 52, 104, 60), fill=(255, 220, 80, 200), outline=STROKE, width=2)
+    # 衣领
+    d.line([(60, 200), (100, 220), (140, 200)], fill=STROKE, width=STROKE_W)
+    return img
+
+
+def classical_queen():
+    img, d = new_canvas()
+    # 长发（披肩）
+    d.polygon([(45, 150), (50, 220), (150, 220), (155, 150),
+               (160, 100), (140, 80), (60, 80), (40, 100)],
+              fill=(200, 80, 80, 100), outline=STROKE, width=STROKE_W)
+    # 脸
+    d.ellipse((62, 102, 138, 178), fill=(255, 224, 189, 150), outline=STROKE, width=STROKE_W)
+    # 眼睛
+    d.ellipse((85, 134, 91, 140), fill=STROKE)
+    d.ellipse((109, 134, 115, 140), fill=STROKE)
+    # 嘴
+    d.arc((90, 150, 110, 164), start=0, end=180, fill=(200, 60, 60, 255), width=3)
+    # 高尖皇冠
+    d.polygon([(75, 75), (100, 30), (125, 75)],
+              fill=(255, 220, 80, 130), outline=STROKE, width=STROKE_W)
+    d.ellipse((96, 30, 104, 40), fill=(255, 220, 80, 200), outline=STROKE, width=2)
+    # 皇冠装饰线
+    d.arc((80, 65, 120, 85), start=0, end=180, fill=STROKE, width=2)
+    return img
+
+
+def classical_king():
+    img, d = new_canvas()
+    # 头发
+    d.polygon([(55, 115), (58, 135), (142, 135), (145, 115), (140, 100), (60, 100)],
+              fill=(120, 90, 60, 100), outline=STROKE, width=STROKE_W)
+    # 脸
+    d.ellipse((60, 100, 140, 180), fill=(255, 224, 189, 150), outline=STROKE, width=STROKE_W)
+    # 眼睛
+    d.ellipse((85, 130, 91, 136), fill=STROKE)
+    d.ellipse((109, 130, 115, 136), fill=STROKE)
+    # 嘴
+    d.line([(88, 152), (112, 152)], fill=STROKE, width=3)
+    # 大胡子
+    d.polygon([(75, 158), (80, 178), (100, 185), (120, 178), (125, 158),
+               (115, 170), (100, 175), (85, 170)],
+              fill=(120, 90, 60, 130), outline=STROKE, width=STROKE_W)
+    # 厚重皇冠
+    d.polygon([(65, 88), (70, 65), (85, 80), (100, 50), (115, 80), (130, 65), (135, 88)],
+              fill=(255, 220, 80, 130), outline=STROKE, width=STROKE_W)
+    # 皇冠红宝石
+    d.rectangle((95, 70, 105, 76), fill=(200, 40, 40, 200), outline=STROKE, width=1)
+    # 衣领
+    d.line([(55, 205), (100, 225), (145, 205)], fill=STROKE, width=STROKE_W)
+    return img
+
+
+def classical_joker():
+    img, d = new_canvas()
+    # 双角帽
+    d.polygon([(60, 95), (70, 35), (80, 85)], fill=(220, 40, 40, 130), outline=STROKE, width=STROKE_W)
+    d.polygon([(140, 95), (130, 35), (120, 85)], fill=(40, 80, 200, 130), outline=STROKE, width=STROKE_W)
+    d.ellipse((65, 30, 75, 40), fill=(220, 40, 40, 200), outline=STROKE, width=2)
+    d.ellipse((125, 30, 135, 40), fill=(40, 80, 200, 200), outline=STROKE, width=2)
+    # 脸
+    d.ellipse((58, 93, 142, 177), fill=(255, 235, 200, 180), outline=STROKE, width=STROKE_W)
+    # 菱形眼
+    d.polygon([(80, 130), (86, 125), (92, 130), (86, 135)], fill=STROKE)
+    d.polygon([(108, 130), (114, 125), (120, 130), (114, 135)], fill=STROKE)
+    # 大嘴
+    d.arc((78, 148, 122, 175), start=0, end=180, fill=(200, 40, 40, 80), width=3)
+    d.arc((78, 148, 122, 175), start=0, end=180, fill=STROKE, width=3)
+    # 领结
+    d.polygon([(90, 200), (100, 195), (110, 200), (100, 215)], fill=(220, 40, 40, 200), outline=STROKE, width=2)
+    return img
+
+
+# ----------------- 现代人物 -----------------
+def modern_child():
+    img, d = new_canvas()
+    # 短发
+    d.chord((55, 80, 145, 115), start=180, end=360, fill=(60, 60, 60, 130), outline=STROKE, width=STROKE_W)
+    # 脸
+    d.ellipse((62, 97, 138, 173), fill=(255, 225, 190, 180), outline=STROKE, width=STROKE_W)
+    # 大眼睛
+    d.ellipse((83, 128, 93, 138), fill=STROKE)
+    d.ellipse((107, 128, 117, 138), fill=STROKE)
+    # 腮红
+    d.ellipse((73, 145, 83, 155), fill=(255, 150, 150, 100))
+    d.ellipse((117, 145, 127, 155), fill=(255, 150, 150, 100))
+    # 嘴
+    d.arc((93, 150, 107, 160), start=0, end=180, fill=STROKE, width=3)
+    return img
+
+
+def modern_young_woman():
+    img, d = new_canvas()
+    # 长发
+    d.polygon([(45, 150), (50, 240), (150, 240), (155, 150),
+               (160, 90), (140, 80), (60, 80), (40, 90)],
+              fill=(80, 40, 30, 130), outline=STROKE, width=STROKE_W)
+    # 脸（椭圆）
+    d.ellipse((65, 98, 135, 178), fill=(255, 225, 190, 180), outline=STROKE, width=STROKE_W)
+    # 眉
+    d.arc((80, 116, 96, 128), start=200, end=340, fill=STROKE, width=3)
+    d.arc((104, 116, 120, 128), start=200, end=340, fill=STROKE, width=3)
+    # 眼睛
+    d.ellipse((85, 132, 91, 138), fill=STROKE)
+    d.ellipse((109, 132, 115, 138), fill=STROKE)
+    # 嘴
+    d.arc((90, 152, 110, 166), start=0, end=180, fill=STROKE, width=3)
+    return img
+
+
+def modern_young_man():
+    img, d = new_canvas()
+    # 短发
+    d.chord((55, 80, 145, 115), start=180, end=360, fill=(40, 30, 20, 130), outline=STROKE, width=STROKE_W)
+    # 脸（方下颌：圆角矩形近似）
+    d.rounded_rectangle((65, 100, 135, 180), radius=18, fill=(255, 225, 190, 180), outline=STROKE, width=STROKE_W)
+    # 眉
+    d.line([(78, 122), (98, 122)], fill=STROKE, width=3)
+    d.line([(102, 122), (122, 122)], fill=STROKE, width=3)
+    # 眼睛
+    d.ellipse((85, 133, 91, 139), fill=STROKE)
+    d.ellipse((109, 133, 115, 139), fill=STROKE)
+    # 嘴
+    d.line([(90, 158), (110, 158)], fill=STROKE, width=3)
+    # 胡茬点
+    d.ellipse((88, 168, 92, 172), fill=STROKE)
+    d.ellipse((98, 170, 102, 174), fill=STROKE)
+    d.ellipse((108, 168, 112, 172), fill=STROKE)
+    return img
+
+
+def modern_clownfish():
+    img, d = new_canvas()
+    # 鱼身
+    d.ellipse((45, 112, 155, 188), fill=(255, 140, 40, 130), outline=STROKE, width=STROKE_W)
+    # 嘴部
+    d.polygon([(55, 150), (40, 145), (40, 155)], fill=(255, 140, 40, 150), outline=STROKE, width=STROKE_W)
+    # 眼睛（白底+黑瞳）
+    d.ellipse((58, 125, 74, 141), fill=(255, 255, 255, 230), outline=STROKE, width=2)
+    d.ellipse((62, 130, 70, 138), fill=STROKE)
+    # 白条纹
+    d.arc((75, 110, 90, 200), start=270, end=90, fill=(255, 255, 255, 200), width=8)
+    d.arc((100, 105, 115, 200), start=270, end=90, fill=(255, 255, 255, 200), width=6)
+    # 背鳍
+    d.polygon([(85, 112), (100, 88), (115, 112)], fill=(255, 140, 40, 130), outline=STROKE, width=STROKE_W)
+    # 腹鳍
+    d.polygon([(90, 188), (95, 208), (105, 188)], fill=(255, 140, 40, 130), outline=STROKE, width=STROKE_W)
+    # 尾鳍
+    d.polygon([(152, 150), (180, 120), (180, 180)], fill=(255, 140, 40, 130), outline=STROKE, width=STROKE_W)
+    return img
+
+
+# ----------------- 天文 -----------------
+def astronomy_star():
+    img, d = new_canvas()
+    cx, cy = 100, 140
+    r_out, r_in = 60, 25
+    pts = []
+    for i in range(10):
+        a = -math.pi / 2 + i * math.pi / 5
+        r = r_out if i % 2 == 0 else r_in
+        pts.append((cx + r * math.cos(a), cy + r * math.sin(a)))
+    d.polygon(pts, fill=(255, 220, 80, 130), outline=STROKE, width=STROKE_W)
+    # 中心高光
+    d.ellipse((94, 134, 106, 146), fill=(255, 255, 200, 200), outline=STROKE, width=1)
+    return img
+
+
+def astronomy_moon():
+    img, d = new_canvas()
+    # 大圆
+    d.ellipse((45, 80, 155, 220), fill=(240, 240, 210, 180), outline=STROKE, width=STROKE_W)
+    # 遮挡圆（右侧偏移实现弯月）
+    d.ellipse((75, 80, 165, 220), fill=(0, 0, 0, 0))  # 透明
+    # 用图层减法实现：在 PIL 中不好做，直接画月牙
+    img2 = Image.new('RGBA', (W, H), (255, 255, 255, 0))
+    d2 = ImageDraw.Draw(img2)
+    d2.ellipse((45, 80, 155, 220), fill=(240, 240, 210, 180), outline=STROKE, width=STROKE_W)
+    # 透明圆覆盖（用镂空 mask）
+    mask = Image.new('L', (W, H), 0)
+    dm = ImageDraw.Draw(mask)
+    dm.ellipse((80, 80, 165, 220), fill=255)
+    out = Image.new('RGBA', (W, H), (0, 0, 0, 0))
+    out.paste(img2, (0, 0), mask)
+    d = ImageDraw.Draw(out)
+    d.ellipse((45, 80, 155, 220), outline=STROKE, width=STROKE_W)
+    # 表面纹理
+    d.ellipse((85, 125, 95, 135), fill=(180, 180, 160, 130))
+    d.ellipse((95, 165, 102, 172), fill=(180, 180, 160, 130))
+    d.ellipse((75, 155, 82, 162), fill=(180, 180, 160, 130))
+    return out
+
+
+def astronomy_sun():
+    img, d = new_canvas()
+    # 8 道光芒
+    rays = [
+        (100, 55, 100, 80),
+        (100, 220, 100, 245),
+        (30, 150, 55, 150),
+        (145, 150, 170, 150),
+        (50, 100, 68, 118),
+        (132, 118, 150, 100),
+        (50, 200, 68, 182),
+        (132, 182, 150, 200),
+    ]
+    for x1, y1, x2, y2 in rays:
+        d.line([(x1, y1), (x2, y2)], fill=STROKE, width=5)
+    # 太阳主体
+    d.ellipse((55, 105, 145, 195), fill=(255, 180, 40, 150), outline=STROKE, width=STROKE_W)
+    # 笑眼
+    d.arc((73, 128, 88, 143), start=200, end=340, fill=STROKE, width=3)
+    d.arc((112, 128, 127, 143), start=200, end=340, fill=STROKE, width=3)
+    # 嘴
+    d.arc((85, 155, 115, 175), start=0, end=180, fill=STROKE, width=3)
+    return img
+
+
+def astronomy_blackhole():
+    img, d = new_canvas()
+    # 吸积盘（两层椭圆）
+    d.ellipse((30, 128, 170, 172), fill=(120, 60, 200, 100), outline=STROKE, width=STROKE_W)
+    d.ellipse((42, 134, 158, 166), fill=(200, 100, 50, 130), outline=STROKE, width=STROKE_W)
+    # 中心黑洞
+    d.ellipse((78, 128, 122, 172), fill=(0, 0, 0, 240), outline=STROKE, width=STROKE_W)
+    # 高光
+    d.ellipse((85, 134, 115, 142), fill=(255, 180, 80, 200))
+    return img
+
+
+# ----------------- 简笔 -----------------
+def minimal_dot():
+    img, d = new_canvas()
+    d.ellipse((45, 95, 155, 205), fill=(80, 180, 200, 150), outline=STROKE, width=STROKE_W)
+    # 内圈虚线
+    d.ellipse((65, 115, 135, 185), outline=STROKE, width=2)
+    # 笑脸
+    d.ellipse((82, 138, 88, 144), fill=STROKE)
+    d.ellipse((112, 138, 118, 144), fill=STROKE)
+    d.arc((85, 155, 115, 170), start=0, end=180, fill=STROKE, width=3)
+    return img
+
+
+def minimal_venus():
+    img, d = new_canvas()
+    d.ellipse((60, 80, 140, 160), fill=(220, 80, 140, 150), outline=STROKE, width=STROKE_W)
+    d.line([(100, 160), (100, 230)], fill=STROKE, width=8)
+    d.line([(80, 200), (120, 200)], fill=STROKE, width=8)
+    return img
+
+
+def minimal_mars():
+    img, d = new_canvas()
+    d.ellipse((40, 120, 120, 200), fill=(60, 120, 220, 150), outline=STROKE, width=STROKE_W)
+    d.line([(115, 120), (155, 80)], fill=STROKE, width=6)
+    d.line([(135, 75), (158, 75)], fill=STROKE, width=6)
+    d.line([(158, 75), (158, 98)], fill=STROKE, width=6)
+    return img
+
+
+def minimal_cross():
+    img, d = new_canvas()
+    # 双色叉：先画浅红底，再深色描边
+    d.line([(55, 95), (155, 225)], fill=(200, 40, 40, 130), width=14)
+    d.line([(155, 95), (55, 225)], fill=(200, 40, 40, 130), width=14)
+    d.line([(55, 95), (155, 225)], fill=STROKE, width=4)
+    d.line([(155, 95), (55, 225)], fill=STROKE, width=4)
+    return img
+
+
+# 元数据
+THEMES = [
+    {
+        'theme_id': 'classical', 'theme_name': '古典宫廷',
+        'description': '王子/皇后/国王/宫廷小丑，传统扑克牌',
+        'items': [
+            ('J',     'prince',  classical_prince,    '王子'),
+            ('Q',     'queen',   classical_queen,     '皇后'),
+            ('K',     'king',    classical_king,      '国王'),
+            ('joker', 'jester',  classical_joker,     '小丑'),
+        ],
+    },
+    {
+        'theme_id': 'modern', 'theme_name': '现代人物',
+        'description': '小孩/女青年/男青年/小丑鱼，日常生活',
+        'items': [
+            ('J',     'child',       modern_child,        '小孩'),
+            ('Q',     'young_woman', modern_young_woman,  '女青年'),
+            ('K',     'young_man',   modern_young_man,    '男青年'),
+            ('joker', 'clownfish',   modern_clownfish,    '小丑鱼'),
+        ],
+    },
+    {
+        'theme_id': 'astronomy', 'theme_name': '天文',
+        'description': '星星/月亮/太阳/黑洞',
+        'items': [
+            ('J',     'star',      astronomy_star,      '星星'),
+            ('Q',     'moon',      astronomy_moon,      '月亮'),
+            ('K',     'sun',       astronomy_sun,       '太阳'),
+            ('joker', 'blackhole', astronomy_blackhole, '黑洞'),
+        ],
+    },
+    {
+        'theme_id': 'minimal', 'theme_name': '简笔符号',
+        'description': '圆点/♀/♂/×，极简风格',
+        'items': [
+            ('J',     'dot',   minimal_dot,    '圆点'),
+            ('Q',     'venus', minimal_venus,  '♀'),
+            ('K',     'mars',  minimal_mars,   '♂'),
+            ('joker', 'cross', minimal_cross,  '×'),
+        ],
+    },
+]
+
+
+class Command(BaseCommand):
+    help = '用 Pillow 画 16 张预设素材 PNG，存到 media/library/，并写入 LibraryAsset 表'
+
+    def handle(self, *args, **options):
+        lib_dir = os.path.join(settings.MEDIA_ROOT, 'library')
+        os.makedirs(lib_dir, exist_ok=True)
+
+        written = 0
+        for theme in THEMES:
+            theme_dir = os.path.join(lib_dir, theme['theme_id'])
+            os.makedirs(theme_dir, exist_ok=True)
+            for role, asset_id, gen_fn, role_name in theme['items']:
+                img = gen_fn()
+                # 上移 30 让主体更靠上，再裁掉 y=150 之后（只留上半身）
+                img = shift_up(img, dy=-30)
+                img = crop_to_upper(img)
+                file_name = f'{asset_id}.png'
+                file_path = os.path.join(theme_dir, file_name)
+                img.save(file_path)
+                rel_path = f'library/{theme["theme_id"]}/{file_name}'
+
+                label = f'{theme["theme_name"]}·{role_name}'
+                obj, created = LibraryAsset.objects.update_or_create(
+                    theme_id=theme['theme_id'],
+                    asset_id=asset_id,
+                    defaults=dict(
+                        theme_name=theme['theme_name'],
+                        role=role,
+                        role_name=role_name,
+                        label=label,
+                        description=theme['description'],
+                        file_path=rel_path,
+                        file_name=file_name,
+                    ),
+                )
+                verb = 'created' if created else 'updated'
+                self.stdout.write(f'  [{verb}] {theme["theme_id"]}/{file_name} -> {label}')
+                written += 1
+
+        self.stdout.write(self.style.SUCCESS(
+            f'\n已生成 {written} 张 PNG 素材（{len(THEMES)} 套主题）\n'
+            f'文件目录: media/library/\n'
+            f'数据库表: apps_projects_libraryasset'
+        ))

backend/apps/projects/migrations/0003_libraryasset.py

@@ -0,0 +1,33 @@
+# Generated by Django 5.2.14 on 2026-06-02 05:49
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('projects', '0002_project_card_overrides_project_design_and_more'),
+    ]
+
+    operations = [
+        migrations.CreateModel(
+            name='LibraryAsset',
+            fields=[
+                ('id', models.BigAutoField(primary_key=True, serialize=False)),
+                ('theme_id', models.CharField(db_index=True, max_length=50)),
+                ('theme_name', models.CharField(max_length=100)),
+                ('role', models.CharField(db_index=True, max_length=10)),
+                ('role_name', models.CharField(max_length=50)),
+                ('asset_id', models.CharField(max_length=50)),
+                ('label', models.CharField(max_length=100)),
+                ('description', models.CharField(blank=True, max_length=255)),
+                ('file_path', models.CharField(max_length=255)),
+                ('file_name', models.CharField(max_length=100)),
+                ('created_at', models.DateTimeField(auto_now_add=True)),
+            ],
+            options={
+                'ordering': ['theme_id', 'role', 'asset_id'],
+                'unique_together': {('theme_id', 'asset_id')},
+            },
+        ),
+    ]

backend/apps/projects/models.py

@@ -104,3 +104,28 @@ class CardLayer(models.Model):
 
     class Meta:
         ordering = ['card_key', 'z_index']
+
+
+class LibraryAsset(models.Model):
+    """预设素材库（与 Project 无关，全局共享）
+    主题分类：classical/modern/astronomy/minimal ...
+    角色：J / Q / K / joker
+    """
+    id = models.BigAutoField(primary_key=True)
+    theme_id = models.CharField(max_length=50, db_index=True)   # classical / modern ...
+    theme_name = models.CharField(max_length=100)              # 古典宫廷 / 现代人物 ...
+    role = models.CharField(max_length=10, db_index=True)      # 'J' / 'Q' / 'K' / 'joker'
+    role_name = models.CharField(max_length=50)                # '王子' / '皇后' ...
+    asset_id = models.CharField(max_length=50)                 # 'prince' / 'queen' ...
+    label = models.CharField(max_length=100)                   # '古典·王子'
+    description = models.CharField(max_length=255, blank=True)
+    file_path = models.CharField(max_length=255)               # library/classical/prince.svg
+    file_name = models.CharField(max_length=100)
+    created_at = models.DateTimeField(auto_now_add=True)
+
+    def __str__(self):
+        return f'{self.theme_name}/{self.role_name}'
+
+    class Meta:
+        ordering = ['theme_id', 'role', 'asset_id']
+        unique_together = [['theme_id', 'asset_id']]

backend/apps/projects/serializers.py

@@ -1,6 +1,6 @@
 from rest_framework import serializers
 from django.conf import settings
-from .models import Project, Asset, CardLayer
+from .models import Project, Asset, CardLayer, LibraryAsset
 
 
 class ProjectSerializer(serializers.ModelSerializer):
@@ -52,3 +52,11 @@ class ProjectDetailSerializer(serializers.ModelSerializer):
             'assets', 'layers',
             'created_at', 'updated_at',
         ]
+
+
+class LibraryAssetSerializer(serializers.ModelSerializer):
+    class Meta:
+        model = LibraryAsset
+        fields = ['id', 'theme_id', 'theme_name', 'role', 'role_name',
+                  'asset_id', 'label', 'description', 'file_path', 'file_name',
+                  'created_at']

backend/apps/projects/urls.py

@@ -3,6 +3,7 @@ from .views import (
     project_list, project_detail, project_save_design,
     asset_list, asset_detail,
 )
+from .views_library import library_list, library_themes, library_detail, library_apply
 
 urlpatterns = [
     path('', project_list, name='project-list'),
@@ -10,4 +11,8 @@ urlpatterns = [
     path('<str:pk>/design/', project_save_design, name='project-save-design'),
     path('<str:project_pk>/assets/', asset_list, name='asset-list'),
     path('<str:project_pk>/assets/<str:asset_pk>/', asset_detail, name='asset-detail'),
+    path('library/', library_list, name='library-list'),
+    path('library/themes/', library_themes, name='library-themes'),
+    path('<str:project_pk>/library/<int:pk>/apply/', library_apply, name='library-apply'),
+    path('library/<int:pk>/', library_detail, name='library-detail'),
 ]

backend/apps/projects/views_library.py

@@ -0,0 +1,114 @@
+from rest_framework.decorators import api_view
+from rest_framework.response import Response
+from rest_framework import status
+from django.conf import settings
+from .models import LibraryAsset, Project, Asset
+from .serializers import LibraryAssetSerializer
+import os
+
+
+@api_view(['GET'])
+def library_list(request):
+    """列出所有预设素材（按主题分组）"""
+    assets = LibraryAsset.objects.all()
+    serializer = LibraryAssetSerializer(assets, many=True, context={'request': request})
+
+    # 按 theme_id 分组
+    grouped = {}
+    for a in serializer.data:
+        a['file_url'] = f'{settings.MEDIA_URL}{a["file_path"]}'
+        grouped.setdefault(a['theme_id'], {
+            'theme_id': a['theme_id'],
+            'theme_name': a['theme_name'],
+            'description': a['description'],
+            'items': [],
+        })['items'].append(a)
+
+    return Response(list(grouped.values()))
+
+
+@api_view(['GET'])
+def library_themes(request):
+    """返回所有主题的元信息（不含具体素材项，用于渲染主题筛选器）"""
+    themes = LibraryAsset.objects.values('theme_id', 'theme_name', 'description').distinct()
+    return Response(list(themes))
+
+
+@api_view(['GET'])
+def library_detail(request, pk):
+    """单个预设素材的详情"""
+    try:
+        a = LibraryAsset.objects.get(pk=pk)
+    except LibraryAsset.DoesNotExist:
+        return Response({'error': 'Not found'}, status=status.HTTP_404_NOT_FOUND)
+    data = LibraryAssetSerializer(a, context={'request': request}).data
+    data['file_url'] = f'{settings.MEDIA_URL}{data["file_path"]}'
+    return Response(data)
+
+
+@api_view(['POST'])
+def library_apply(request, project_pk, pk):
+    """把预设素材应用到项目某张牌（默认：spade-J / joker-big 等）
+    请求体: { card_key?: 'spade-J' }  可选；不传则用预设素材的 role + 默认 spade
+    """
+    try:
+        project = Project.objects.get(pk=project_pk)
+        lib = LibraryAsset.objects.get(pk=pk)
+    except (Project.DoesNotExist, LibraryAsset.DoesNotExist):
+        return Response({'error': 'not found'}, status=status.HTTP_404_NOT_FOUND)
+
+    card_key = request.data.get('card_key')
+    if not card_key:
+        # 默认: spade-{role} 或 joker-{which}
+        if lib.role == 'joker':
+            card_key = 'joker-big'  # 默认应用到 big；用户可换
+        else:
+            card_key = f'spade-{lib.role}'
+
+    # 决定 asset_type: J/Q/K -> face_card；joker -> joker
+    asset_type = 'face_card' if lib.role in ('J', 'Q', 'K') else 'joker'
+    asset_key = card_key
+
+    # 删除该项目同 (asset_type, asset_key) 的旧记录（避免重复）
+    Asset.objects.filter(project=project, asset_type=asset_type, asset_key=asset_key).delete()
+
+    # 复制 library 文件到 projects/<pid>/ 下，避免污染原文件
+    import shutil
+    from time import time
+    project_media_dir = os.path.join('projects', str(project.id), asset_type)
+    full_dir = os.path.join(settings.MEDIA_ROOT, project_media_dir)
+    os.makedirs(full_dir, exist_ok=True)
+
+    src_path = os.path.join(settings.MEDIA_ROOT, lib.file_path)
+    ts = int(time() * 1000)
+    new_file_name = f'{asset_key}_{ts}_{lib.file_name}'
+    dst_rel = os.path.join(project_media_dir, new_file_name)
+    dst_abs = os.path.join(settings.MEDIA_ROOT, dst_rel)
+    shutil.copy2(src_path, dst_abs)
+
+    # 读 svg 尺寸
+    width = height = None
+    try:
+        from PIL import Image
+        with Image.open(dst_abs) as im:
+            width, height = im.size
+    except Exception:
+        pass
+
+    asset = Asset.objects.create(
+        project=project,
+        asset_type=asset_type,
+        asset_key=asset_key,
+        file_path=dst_rel,
+        file_name=new_file_name,
+        width=width,
+        height=height,
+    )
+
+    return Response({
+        'ok': True,
+        'asset_id': asset.id,
+        'card_key': card_key,
+        'asset_type': asset_type,
+        'file_url': f'{settings.MEDIA_URL}{dst_rel}',
+    }, status=status.HTTP_201_CREATED)

frontend/src/components/AssetPanel.vue

@@ -5,7 +5,18 @@
       <button class="primary" @click="showUpload = true">+ 上传</button>
     </div>
 
-    <!-- JQK 人物图 -->
+    <!-- 标签页 -->
+    <div class="tabs">
+      <button :class="['tab', { active: activeTab === 'mine' }]" @click="activeTab = 'mine'">
+        我的素材
+      </button>
+      <button :class="['tab', { active: activeTab === 'library' }]" @click="activeTab = 'library'">
+        预设主题
+      </button>
+    </div>
+
+    <!-- 我的素材 tab -->
+    <div v-if="activeTab === 'mine'">
       <section v-if="faceCardAssets.length">
         <h5>JQK 人物图</h5>
         <div class="grid">
@@ -19,21 +30,19 @@
         </div>
       </section>
 
-    <!-- 大小王 -->
       <section v-if="jokerAssets.length">
         <h5>大小王</h5>
         <div class="grid">
           <div v-for="a in jokerAssets" :key="a.id" class="asset-tile">
             <img :src="a.file_url" />
             <div class="meta">
-            <div class="key">{{ a.asset_key === 'big' ? '大王' : '小王' }}</div>
+              <div class="key">{{ a.asset_key === 'joker-big' ? '大王' : a.asset_key === 'joker-small' ? '小王' : a.asset_key }}</div>
               <button class="mini ghost" @click="del(a)">删除</button>
             </div>
           </div>
         </div>
       </section>
 
-    <!-- 背面 -->
       <section v-if="backAssets.length">
         <h5>背面图案</h5>
         <div class="grid">
@@ -51,6 +60,59 @@
         <p>还没有素材</p>
         <p class="hint">点击右上「上传」按钮，添加 JQK 人物、大小王图或背面</p>
         <p class="hint">JQK 只需上传上半身图，系统会自动生成中心对称的完整牌面</p>
+        <p class="hint">或切到「预设主题」标签页快速套用 4 套主题</p>
+      </div>
+    </div>
+
+    <!-- 预设主题 tab -->
+    <div v-else-if="activeTab === 'library'">
+      <div v-if="libraryLoading" class="loading">加载主题中…</div>
+      <div v-else-if="libraryError" class="empty error">{{ libraryError }}</div>
+      <div v-else>
+        <!-- 主题筛选 -->
+        <div class="theme-filter">
+          <button
+            :class="['theme-tab', { active: !selectedTheme }]"
+            @click="selectedTheme = null"
+          >全部</button>
+          <button
+            v-for="t in themes"
+            :key="t.theme_id"
+            :class="['theme-tab', { active: selectedTheme === t.theme_id }]"
+            @click="selectedTheme = t.theme_id"
+          >{{ t.theme_name }}</button>
+        </div>
+
+        <div v-if="selectedThemeObj" class="theme-desc">
+          {{ selectedThemeObj.description }}
+        </div>
+
+        <div v-if="filteredGroups.length === 0" class="empty">
+          <p>该主题没有素材</p>
+        </div>
+
+        <div v-for="g in filteredGroups" :key="g.theme_id" class="lib-group">
+          <h5 class="lib-group-title">
+            <span>{{ g.theme_name }}</span>
+            <span class="lib-count">{{ g.items.length }} 张</span>
+          </h5>
+          <div class="grid">
+            <div
+              v-for="lib in g.items"
+              :key="lib.id"
+              :class="['asset-tile', { applying: applyingId === lib.id }]"
+              @click="applyLib(lib)"
+              :title="`点击应用到当前牌位：${targetCardKey}`"
+            >
+              <img :src="`/media/${lib.file_path}`" />
+              <div class="meta">
+                <div class="key">{{ lib.role_name }}</div>
+                <div class="lib-action">{{ applyingId === lib.id ? '应用中…' : '点击套用' }}</div>
+              </div>
+            </div>
+          </div>
+        </div>
+      </div>
     </div>
 
     <AssetUploadDialog
@@ -62,7 +124,7 @@
 </template>
 
 <script setup>
-import { ref, computed } from 'vue'
+import { ref, computed, onMounted, watch } from 'vue'
 import { ElMessageBox, ElMessage } from 'element-plus'
 import axios from 'axios'
 import { useProjectStore } from '@/stores/projectStore'
@@ -70,7 +132,9 @@ import AssetUploadDialog from '@/components/AssetUploadDialog.vue'
 
 const store = useProjectStore()
 const showUpload = ref(false)
+const activeTab = ref('mine')
 
+// ----- 我的素材 -----
 const assets = computed(() => store.project?.assets || [])
 const faceCardAssets = computed(() => assets.value.filter(a => a.asset_type === 'face_card'))
 const jokerAssets    = computed(() => assets.value.filter(a => a.asset_type === 'joker'))
@@ -91,6 +155,75 @@ async function del(a) {
     if (e !== 'cancel') ElMessage.error('删除失败: ' + e.message)
   }
 }
+
+// ----- 预设主题 -----
+const library = ref([])
+const libraryLoading = ref(false)
+const libraryError = ref('')
+const selectedTheme = ref(null)
+const applyingId = ref(null)
+
+const themes = computed(() => library.value.map(g => ({
+  theme_id: g.theme_id,
+  theme_name: g.theme_name,
+  description: g.description,
+})))
+const selectedThemeObj = computed(() =>
+  selectedTheme.value ? themes.value.find(t => t.theme_id === selectedTheme.value) : null
+)
+const filteredGroups = computed(() => {
+  if (!selectedTheme.value) return library.value
+  return library.value.filter(g => g.theme_id === selectedTheme.value)
+})
+
+// 当前牌位 key（点击预设时套用到哪张牌）
+const targetCardKey = computed(() => store.currentCard || 'spade-A')
+
+async function loadLibrary() {
+  libraryLoading.value = true
+  libraryError.value = ''
+  try {
+    const r = await axios.get('/api/projects/library/')
+    library.value = r.data || []
+  } catch (e) {
+    libraryError.value = '加载预设失败: ' + e.message
+  } finally {
+    libraryLoading.value = false
+  }
+}
+
+async function applyLib(lib) {
+  if (!store.project) {
+    ElMessage.warning('请先创建/打开项目')
+    return
+  }
+  applyingId.value = lib.id
+  try {
+    const cardKey = targetCardKey.value
+    // 根据 lib.role 决定 asset_type
+    const assetType = (lib.role === 'joker') ? 'joker' : 'face_card'
+    const r = await axios.post(
+      `/api/projects/${store.project.id}/library/${lib.id}/apply/`,
+      { card_key: cardKey }
+    )
+    ElMessage.success(`已套用「${lib.label}」到 ${cardKey}`)
+    await store.refreshAssets()
+  } catch (e) {
+    ElMessage.error('套用失败: ' + (e.response?.data?.error || e.message))
+  } finally {
+    applyingId.value = null
+  }
+}
+
+watch(activeTab, (val) => {
+  if (val === 'library' && library.value.length === 0) {
+    loadLibrary()
+  }
+})
+
+onMounted(() => {
+  if (activeTab.value === 'library') loadLibrary()
+})
 </script>
 
 <style scoped>
@@ -98,16 +231,37 @@ async function del(a) {
 .asset-panel h5 { margin: 0 0 8px 0; font-size: 12px; color: #aaa; }
 .header { display: flex; justify-content: space-between; align-items: center; margin-bottom: 12px; }
 button.primary { background: #e94560; color: #fff; border: none; border-radius: 3px; padding: 4px 10px; font-size: 12px; cursor: pointer; }
+.tabs { display: flex; gap: 4px; margin-bottom: 12px; border-bottom: 1px solid #16213e; }
+.tab { flex: 1; background: transparent; color: #888; border: none; border-bottom: 2px solid transparent; padding: 6px 0; font-size: 12px; cursor: pointer; }
+.tab.active { color: #e94560; border-bottom-color: #e94560; }
+
 section { margin-bottom: 16px; padding-bottom: 12px; border-bottom: 1px solid #16213e; }
 .grid { display: grid; grid-template-columns: repeat(2, 1fr); gap: 6px; }
-.asset-tile { background: #16213e; border-radius: 4px; overflow: hidden; }
+.asset-tile { background: #16213e; border-radius: 4px; overflow: hidden; cursor: default; }
+.asset-tile.applying { opacity: 0.5; }
+.lib-group .asset-tile { cursor: pointer; transition: all 0.15s; }
+.lib-group .asset-tile:hover { background: #e94560; transform: translateY(-2px); }
 .asset-tile img { width: 100%; height: 70px; object-fit: contain; background: #fff; }
 .asset-tile .meta { display: flex; justify-content: space-between; align-items: center; padding: 4px 6px; }
 .asset-tile .key { font-size: 11px; color: #ccc; }
+.asset-tile .lib-action { font-size: 10px; color: #888; }
+
 .mini { font-size: 10px; padding: 2px 6px; border: none; border-radius: 3px; cursor: pointer; }
 .mini.ghost { background: transparent; color: #888; border: 1px solid #444; }
 .mini.ghost:hover { color: #e94560; border-color: #e94560; }
+
 .empty { text-align: center; padding: 20px 8px; color: #777; }
 .empty p { margin: 4px 0; font-size: 12px; }
 .empty .hint { font-size: 11px; color: #555; line-height: 1.4; }
+.empty.error { color: #e94560; }
+.loading { text-align: center; padding: 20px; color: #888; font-size: 12px; }
+
+.theme-filter { display: flex; gap: 4px; flex-wrap: wrap; margin-bottom: 10px; }
+.theme-tab { background: #16213e; color: #aaa; border: none; padding: 4px 8px; border-radius: 3px; font-size: 11px; cursor: pointer; }
+.theme-tab.active { background: #e94560; color: #fff; }
+.theme-desc { font-size: 11px; color: #888; margin-bottom: 10px; line-height: 1.4; }
+
+.lib-group { margin-bottom: 16px; }
+.lib-group-title { display: flex; justify-content: space-between; align-items: center; margin: 0 0 8px 0; font-size: 12px; color: #ccc; }
+.lib-count { font-size: 10px; color: #777; }
 </style>