def save_avatar(folder):
 """
 保存微信好友头像
 :param folder: 保存的文件夹
 """
 itchat.auto_login(hotReload=True)
 users = itchat.get_friends() or []
 print('%d friends found.' % len(users))
 if not os.path.exists(folder):
  os.makedirs(folder)
 index = 1
 for i, user in enumerate(users):
  nickname = user.RemarkName
  username = user.UserName
  file_path = os.path.join(folder, '%03d_%s.png' % (i, nickname))
  if not os.path.isfile(file_path): # 不重复下载
   avatar = itchat.get_head_img(username)
   with open(file_path, 'w') as f:
    f.write(avatar)
    print('Download %d: %s' % (index, file_path))
    index += 1

def get_image_files(folder, filters=None):
 """
 取出待拼接头像
 :param folder: 目标文件夹
 :param filters: 需要过滤的图片
 :return: 头像路径
 """
 filters = filters or []
 filenames = [os.path.join(folder, sub) for sub in os.listdir(folder)
     if sub.endswith('.png') and not filters.__contains__(sub)]
 return filenames

def calculate_align_way(image_num, force_align=False):
 """
 计算图片排版对齐方式
 :param image_num: 图片数量
 :return: (rowls, columns)
 """
 actual_value = image_num ** 0.5
 suggest_value = int(actual_value)
 if actual_value == suggest_value or force_align:
  return suggest_value, suggest_value
 else:
  return suggest_value, suggest_value + 1

def join_images(image_files, rows, cols, width, height, save_file=None):
 """
 拼接操作
 :param image_files: 待拼接的图片
 :param rows: 行数
 :param cols: 列数
 :param width: 每张小头像的宽度
 :param height: 每张小头像的高度
 :param save_file: 拼接好图片的保存路径
 """
 canvas = np.ones((height * rows, width * cols, 3), np.uint8)
 for row in range(rows):
  for col in range(cols):
   index = row * cols + col
   if index >= len(image_files):
    break
   file_path = image_files[index]
   im = Image.open(file_path)
   im = im.resize((width, height))
   im_data = np.array(im)
   if len(im_data.shape) == 2:
    im_data = np.expand_dims(im_data, -1)
   x = col * width
   y = row * height
   canvas[y: y + height, x: x + width, :] = im_data
 image = Image.fromarray(canvas)
 image.show()
 if save_file:
  image.save(save_file)

FOLDER = 'avatars'

if __name__ == '__main__':
 # 保存所有好友头像
 save_avatar(FOLDER)

 # 取到准备拼接的头像
 image_files = get_image_files(FOLDER)

 # 计算拼接的行列
 rows, columns = calculate_align_way(len(image_files), force_align=True)

 # 执行拼接操作
 join_images(image_files, rows, columns, 64, 64, 'result.png')