Python：使用Scrapy框架的Imagepipeline组件如何下载gif呢?

Question

默认情况下，使用Scrapy的ImagePipeline组件下载图片的时候，不论之前的图片格式是png还是gif，都会被保存成jpeg格式。
通过重写file_path方法，可以将图片以原来的格式和原图片名称进行保存。

---

重写file_path方法

__author__ = 'Fly'  
#coding:utf-8  
from scrapy.contrib.pipeline.images import ImagesPipeline  
from scrapy.http import Request  
from scrapy.exceptions import DropItem  

class MyImagesPipeline(ImagesPipeline):  
    def file_path(self, request, response=None, info=None):  
        image_guid = request.url.split('/')[-1]  
        return 'full/%s' % (image_guid)  

    def get_media_requests(self, item, info):  
        for image_url in item['image_urls']:  
            yield Request(image_url)  

    def item_completed(self, results, item, info):  
        image_paths = [x['path'] for ok, x in results if ok]  
        if not image_paths:  
            raise DropItem("Item contains no images")  
        return item

---

运行结果

图片URL：http://www.baidu.com/1.gif
保存到本地：1.gif
但是，当打开1.gif的时候，发现原本动态的图片现在却变成静态的了。
请问，有谁知道怎么处理吗？

Answer 1

试着覆盖convertimage

https://github.com/scrapy/scrapy/blob/master/scrapy/contrib/pipeline/images.py#L87

__author__ = 'Fly'  
#coding:utf-8  
from scrapy.contrib.pipeline.images import ImagesPipeline  
from scrapy.http import Request  
from scrapy.exceptions import DropItem  

class MyImagesPipeline(ImagesPipeline):  
    def file_path(self, request, response=None, info=None):  
        image_guid = request.url.split('/')[-1]  
        return 'full/%s' % (image_guid)  

    def get_media_requests(self, item, info):  
        for image_url in item['image_urls']:  
            yield Request(image_url)  

    def item_completed(self, results, item, info):  
        image_paths = [x['path'] for ok, x in results if ok]  
        if not image_paths:  
            raise DropItem("Item contains no images")  
        return item

    def convert_image(self, image, size=None): 
        buf = StringIO()
        image.save(buf)
        return image, buf

试试，可能会出错，文档上说这个pipeline会：

Convert all downloaded images to a common format (JPG) and mode (RGB)
Avoid re-downloading images which were downloaded recently
Thumbnail generation
Check images width/height to make sure they meet a minimum constraint