python打开网络图片并缩放

 # -*- coding:utf-8 -*-
 ''''' tk_image_view_url_io_resize.py
 display an image from a URL using Tkinter, PIL and data_stream
 also resize the web image to fit a certain size display widget
 retaining its aspect ratio
 Pil facilitates resizing and allows file formats other then gif
 tested with Python27 and Python33 by vegaseat 18mar2013
 '''
 ''''' tk_image_view_url_io_resize.py
 用Tkinter, PIL和data_stream从一个url地址加载图片，
 能保持比例缩放适应显示大小， Pil便于缩放和读取各种图像格式，
 在Python27和Python33上都测试过了 by vegaseat 18mar2013
 '''

 import io
 from PIL import Image, ImageTk
 try:
   # Python2
   import Tkinter as tk
   from urllib2 import urlopen
 except ImportError:
   # Python3
   import tkinter as tk
   from urllib.request import urlopen
 def 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
   对一个pil_image对象进行缩放，让它在一个矩形框内，还能保持比例
   '''


   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 want
 #期望图像显示的大小
 w_box = 400
 h_box = 400
 # 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 it
 #从网页上找到一个图片，复制它的网址，这里网址太长，所以分开了
 url1 = "http://freeflowerpictures.net/image/flowers/petunia/"
 url2 = "petunia-flower.jpg"
 url = url1 + url2
 image_bytes = urlopen(url).read()
 # internal data file
 data_stream = io.BytesIO(image_bytes)

 # open as a PIL image object
 #以一个PIL图像对象打开
 pil_image = Image.open(data_stream)

 # get the size of the image
 #获取图像的原始大小
 w, h = pil_image.size

 # resize the image so it retains its aspect ration
 # but fits into the specified display box
 #缩放图像让它保持比例，同时限制在一个矩形框范围内
 pil_image_resized = resize(w, h, w_box, h_box, pil_image)

 # optionally show resized image info ...
 # get the size of the resized image
 # 也可以显示缩放后的图像信息，获取大小
 wr, hr = pil_image_resized.size

 # split off image file name
 # 标题栏显示：缩放后的图像文件名和大小
 fname = url.split('/')[-1]
 sf = "resized {} ({}x{})".format(fname, wr, hr)
 root.title(sf)

 # convert PIL image object to Tkinter PhotoImage object
 # 把PIL图像对象转变为Tkinter的PhotoImage对象
 tk_image = ImageTk.PhotoImage(pil_image_resized)

 # put the image on a widget the size of the specified display box
 # Label: 这个小工具，就是个显示框，小窗口，把图像大小显示到指定的显示框
 label = tk.Label(root, image=tk_image, width=w_box, height=h_box)
 #padx,pady是图像与窗口边缘的距离
 label.pack(padx=5, pady=5)
 root.mainloop()

 # -*- coding:utf-8 -*-
 ''''' tk_image_view_url_io_resize.py
 display an image from a URL using Tkinter, PIL and data_stream
 also resize the web image to fit a certain size display widget
 retaining its aspect ratio
 Pil facilitates resizing and allows file formats other then gif
 tested with Python27 and Python33 by vegaseat 18mar2013
 '''
 ''''' tk_image_view_url_io_resize.py
 用Tkinter, PIL和data_stream从一个url地址加载图片，
 能保持比例缩放适应显示大小， Pil便于缩放和读取各种图像格式，
 在Python27和Python33上都测试过了 by vegaseat 18mar2013
 '''

 import io
 from PIL import Image, ImageTk
 try:
   # Python2
   import Tkinter as tk
   from urllib2 import urlopen
 except ImportError:
   # Python3
   import tkinter as tk
   from urllib.request import urlopen
 def 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
   对一个pil_image对象进行缩放，让它在一个矩形框内，还能保持比例
   '''


   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 want
 #期望图像显示的大小
 w_box = 400
 h_box = 400
 # 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 it
 #从网页上找到一个图片，复制它的网址，这里网址太长，所以分开了
 url1 = "http://freeflowerpictures.net/image/flowers/petunia/"
 url2 = "petunia-flower.jpg"
 url = url1 + url2
 image_bytes = urlopen(url).read()
 # internal data file
 data_stream = io.BytesIO(image_bytes)

 # open as a PIL image object
 #以一个PIL图像对象打开
 pil_image = Image.open(data_stream)

 # get the size of the image
 #获取图像的原始大小
 w, h = pil_image.size

 # resize the image so it retains its aspect ration
 # but fits into the specified display box
 #缩放图像让它保持比例，同时限制在一个矩形框范围内
 pil_image_resized = resize(w, h, w_box, h_box, pil_image)

 # optionally show resized image info ...
 # get the size of the resized image
 # 也可以显示缩放后的图像信息，获取大小
 wr, hr = pil_image_resized.size

 # split off image file name
 # 标题栏显示：缩放后的图像文件名和大小
 fname = url.split('/')[-1]
 sf = "resized {} ({}x{})".format(fname, wr, hr)
 root.title(sf)

 # convert PIL image object to Tkinter PhotoImage object
 # 把PIL图像对象转变为Tkinter的PhotoImage对象
 tk_image = ImageTk.PhotoImage(pil_image_resized)

 # put the image on a widget the size of the specified display box
 # Label: 这个小工具，就是个显示框，小窗口，把图像大小显示到指定的显示框
 label = tk.Label(root, image=tk_image, width=w_box, height=h_box)
 #padx,pady是图像与窗口边缘的距离
 label.pack(padx=5, pady=5)
 root.mainloop()