python - 如何使用 XML 存储和读取字节字符串(PyGame 图像)？我收到 ValueError 或 TypeError (无法序列化)。

Question

我正在尝试将图像转换为字符串，再转换为字节，然后再转换回图像，但某些地方出现了问题，我真的不知道是什么。我正在使用 Python 3.3 和 pygame。

我需要对字符串执行此操作的原因是，稍后我计划将字符串导出到 XML 文件，并且当我提取变量时，它无论如何都会以 unicode 字符串类型出现。

对于这个恼人的问题，任何帮助都将不胜感激。

import pygame
pygame.init()
displaysurf = pygame.display.set_mode((500, 500))

dirtImg = pygame.image.load('1.gif')
dirtXY= dirtImg.get_size()
print(dirtXY)

dirtText = str(pygame.image.tostring(dirtImg,'RGBX',False))



dirtBytes = bytes(dirtText, 'utf8' )
print(type(dirtBytes))
#prints out <class 'bytes'>


testimg = pygame.image.fromstring(dirtBytes, dirtXY, 'RGBX')

错误信息

  Traceback (most recent call last):
      File "C:\Users\Derek\workspace\Test\test.py", line 18, in <module>

  testimg = pygame.image.fromstring(dirtBytes, dirtXY, 'RGBX')
      ValueError: String length does not equal format and resolution size

显然我不会随时更改图像，因此它必须在编码或解码为字节中。如果有更好的方法请告诉

Answer 1

与 ddaniels 聊天后讨论，我发现这是他正在使用的流程:

• pygame 图像
• --> pygame 字节串
• --> 手动复制粘贴到 xml
• --> 从 xml 读取
• --> pygame 图像(此处失败)

我认为复制粘贴对于其他可能发现这一点的人来说并不是一个通用的解决方案，所以我找到了一种从 pygame 图像到 xml 再回到 pygame 的方法。在 Python 2 中更简单，但此代码适用于 Python 2 和 Python 3。

如果有人知道如何简化此过程，请告诉我。

import pygame
import base64
import xml.etree.ElementTree as ET
pygame.init()
dirt_image = pygame.image.load('dirt.gif')
dirt_xy = dirt_image.get_size()

# incantation starts here
# The result of tostring is a bytestring with basically binary data.
dirt_bytes = pygame.image.tostring(dirt_image, 'RGBX', False)
# b64 encode so that we have all printable characters in the string.
# Otherwise elementtree doesn't want to accept the content.
# The result is another byte string but with printable characters.
dirt_bytes_in_64 = base64.b64encode(dirt_bytes)
# in Python 3, ElementTree complains about bytestrings so we further encode
# it into utf-8. In Python 2, this is not necessary.
dirt_bytes_in_64_in_utf8 = dirt_bytes_in_64.decode('utf-8')

# ElementTree create, save, restore
root = ET.Element("root")
dirt = ET.SubElement(root, 'dirt')
dirt.set('bytes64utf8', dirt_bytes_in_64_in_utf8)
tree = ET.ElementTree(root)
tree.write('images.xml')
tree_restored = ET.parse('images.xml')
dirt_bytes_in_64_in_utf8_restored = tree_restored.find('dirt').get('bytes64utf8')

# Convert from utf-8 back to base64 bytestring.
dirt_bytes_in_64_restored = dirt_bytes_in_64_in_utf8_restored.encode('utf-8')
# Convert from base64 bytestring into the original binary bytestring
dirt_bytes_restored = base64.b64decode(dirt_bytes_in_64_restored)

# Shazam. (for me at least)
restored_image = pygame.image.fromstring(dirt_bytes_restored, dirt_xy, 'RGBX')
display_surf = pygame.display.set_mode((500, 500))
display_surf.blit(dirt_image, (0, 0))
display_surf.blit(restored_image, (32, 32))
pygame.display.flip()