python使用PIL缩放网络图片并保存的方法

''' tk_image_view_url_io_resize.pydisplay an image from a URL using Tkinter, PIL and data_streamalso resize the web image to fit a certain size display widgetretaining its aspect ratioPil facilitates resizing and allows file formats other then giftested with Python27 and Python33 by vegaseat 18mar2013'''import iofrom PIL import Image, ImageTktry:  # Python2  import Tkinter as tk  from urllib2 import urlopenexcept ImportError:  # Python3  import tkinter as tk  from urllib.request import urlopendef resize(w, h, w_box, h_box, pil_image):  '''  resize a pil_image object so it will fit into  a box of size w_box times h_box, but retain aspect ratio  '''  f1 = 1.0*w_box/w # 1.0 forces float division in Python2  f2 = 1.0*h_box/h  factor = min([f1, f2])  #print(f1, f2, factor) # test  # use best down-sizing filter  width = int(w*factor)  height = int(h*factor)  return pil_image.resize((width, height), Image.ANTIALIAS)root = tk.Tk()# size of image display box you wantw_box = 400h_box = 350# find yourself a picture on an internet web page you like# (right click on the picture, under properties copy the address)# a larger (1600 x 1200) picture from the internet# url name is long, so split iturl1 = "http://freeflowerpictures.net/image/flowers/petunia/"url2 = "petunia-flower.jpg"url = url1 + url2image_bytes = urlopen(url).read()# internal data filedata_stream = io.BytesIO(image_bytes)# open as a PIL image objectpil_image = Image.open(data_stream)# get the size of the imagew, h = pil_image.size# resize the image so it retains its aspect ration# but fits into the specified display boxpil_image_resized = resize(w, h, w_box, h_box, pil_image)# optionally show resized image info ...# get the size of the resized imagewr, hr = pil_image_resized.size# split off image file namefname = url.split('/')[-1]sf = "resized {} ({}x{})".format(fname, wr, hr)root.title(sf)# convert PIL image object to Tkinter PhotoImage objecttk_image = ImageTk.PhotoImage(pil_image_resized)# put the image on a widget the size of the specified display boxlabel = tk.Label(root, image=tk_image, width=w_box, height=h_box)label.pack(padx=5, pady=5)root.mainloop()