在爬完网上一篇帖子，并得到其中的所有图片链接后，写一个GUI来实现在线预览是一个很自然的想法， 相当于实现一个python版的图片浏览器， 通过这个练习，可以让我们更熟悉PyQt这个库。
这里我用的是PyQt4。
以下是我的写的程序，可以实现以下几个功能。
预览图片：
实现鼠标左键单击即可下翻至下一张图片，鼠标右键单击则是返回前一张图片。
利用本地Cache来解决反复读取的问题。 比如说对同样的两张图片我们想来回比较，我们没必要每次都重新下载。我们可以将图片保存到本地，当以后调用同一张图片时，直接从本地读取缓存来加速。如果我们不想让外界看到缓存的图片，则可以对其进行加密 (尚未实现)。
对动图gif的支持。普通的 jpg 和 Png 格式，利用QLable 即可以显示，但是对于gif，我们则必须利用QMovie来让其动起来。
由于我刚接触这个库，仍然在学习，所以写的不妥或者冗余的地方，希望大家指出。
# coding=utf-8
import sys
import pycurl
import os
import time
from StringIO import StringIO
import re
from PyQt4 import QtGui,QtCore
from PyQt4.QtGui import *
from PyQt4.QtCore import *
# class definition
class Pic_Label(QtGui.QLabel):
def __init__(self):
super(Pic_Label,self).__init__()
self.setFrameStyle(QtGui.QFrame.StyledPanel)
self.cache_map={}
def paintEvent(self, event):
if self.extention !="gif":
size = self.size()
painter = QtGui.QPainter(self)
point = QtCore.QPoint(0,0)
scaledPix = self.pixmap.scaled(size, Qt.KeepAspectRatio, transformMode = Qt.SmoothTransformation)
# start painting the label from left upper corner
point.setX((size.width() - scaledPix.width())/2)
point.setY((size.height() - scaledPix.height())/2)
#print point.x(), ' ', point.y()
painter.drawPixmap(point, scaledPix)
else:
QLabel.paintEvent(self, event)
def mouseReleaseEvent(self,ev):
#self.emit(SIGNAL('clicked()'))
if ev.button() == Qt.RightButton:
self.emit(SIGNAL("RightClick"))
else:
self.emit(SIGNAL("LeftClick"))
def set_image(self,pic_url,index):
if (index in self.cache_map) == False:
self.cache_map[index]=False
self.pixmap = QtGui.QPixmap()
self.retrieve_from_url_cache(pic_url,index)
def retrieve_from_url_cache(self,pic_url,index):
try:
self.extention=re.search(r"\.(\w+)$", pic_url).group(1)
except:
self.extention="jpg"
cache_pic_name="Pic_"+str(index)+"."+self.extention
cache_pic_path=os.getcwd()+"\Cache_Pic\\"+cache_pic_name
if self.cache_map[index]==True:
if self.extention =="gif":
movie = QtGui.QMovie(cache_pic_path)
self.setMovie(movie)
movie.start()
else:
#print "Cached!" + cache_pic_path
if self.pixmap.load(cache_pic_path) == False:
#print "use jpg to try again"
if self.pixmap.load(cache_pic_path)== False:
#last resort, try again
self.retrieve_from_url(pic_url,index,cache_pic_path)
self.setPixmap(self.pixmap) # udpate immediately
else:
if self.extention =="gif":
data=self.retrieve_from_url(pic_url,index,cache_pic_path)
self.pixmap.loadFromData(data)
f = open(cache_pic_path, 'wb')
f.write(data)
f.close()
movie = QtGui.QMovie(cache_pic_path)
self.setMovie(movie)
movie.start()
else:
data=self.retrieve_from_url(pic_url,index,cache_pic_path)
self.pixmap.loadFromData(data)
self.pixmap.save(cache_pic_path)
self.setPixmap(self.pixmap) # udpate immediately
def retrieve_from_url(self,pic_url,index,file_path):
c = pycurl.Curl()
c.setopt(pycurl.PROXY, 'http://192.168.87.15:8080')
c.setopt(pycurl.PROXYUSERPWD, 'LL66269:')
c.setopt(pycurl.PROXYAUTH, pycurl.HTTPAUTH_NTLM)
buffer = StringIO()
c.setopt(pycurl.URL, pic_url)
c.setopt(c.WRITEDATA, buffer)
c.perform()
c.close()
data = buffer.getvalue()
self.cache_map[index]=True
return data
def setMovie(self,movie):
QLabel.setMovie(self, movie)
s=movie.currentImage().size()
self._movieWidth = s.width()
self._movieHeight = s.height()
class Example(QtGui.QWidget):
def __init__(self,thread_url_list):
super(Example, self).__init__()
self.url_list=thread_url_list
self.current_pic_index=0
cwd = os.getcwd()
#print cwd
directory=cwd+"\Cache_Pic"
#print directory
if not os.path.exists(directory):
os.makedirs(directory)
self.initUI()
# making subfolderss to cache pictures
def initUI(self):
layout = QtGui.QGridLayout()
self.label = Pic_Label()
self.label.set_image(self.url_list[0],0)
#self.label = QLabel()
#movie = QtGui.QMovie("Cache_Pic/Pic_0.gif")
#self.label.setMovie(movie)
#movie.start()
layout.addWidget(self.label)
layout.setRowStretch(0,1)
layout.setColumnStretch(0,1)
#self.connect(self.label,SIGNAL('clicked()'),self.fun_next)
self.connect(self.label,SIGNAL("LeftClick"),self.fun_next)
self.connect(self.label,SIGNAL("RightClick"),self.fun_prev)
#b1=QtGui.QPushButton("next")
#b2=QtGui.QPushButton("prev")
#b1.clicked.connect(self.fun_next)
#b2.clicked.connect(self.fun_prev)
#layout.addWidget(b1)
#layout.addWidget(b2)
self.setLayout(layout)
self.setGeometry(300, 300, 500, 500)
self.setWindowTitle('Picture Viewer')
self.show()
# Connect button to image updating
def fun_next(self):
if self.current_pic_index < len(self.url_list)-1:
self.current_pic_index=self.current_pic_index+1
else:
self.current_pic_index=0
self.label.set_image(self.url_list[self.current_pic_index],self.current_pic_index)
sys.stdout.write('\r')
sys.stdout.write("[ %d ] out of (%d)" % (self.current_pic_index+1,len(self.url_list)))
sys.stdout.flush()
def fun_prev(self):
if self.current_pic_index > 0:
self.current_pic_index=self.current_pic_index-1
else:
self.current_pic_index=len(self.url_list)-1
self.label.set_image(self.url_list[self.current_pic_index],self.current_pic_index)
sys.stdout.write('\r')
sys.stdout.write("[ %d ] out of (%d)" % (self.current_pic_index+1,len(self.url_list)))
sys.stdout.flush()
def view_image():
url_list=['https://i.imgur.com/waprhO3.gif','http://static.cnbetacdn.com/article/2017/0831/7f11d5ec94fa123.png','http://static.cnbetacdn.com/article/2017/0831/1b6595175fb5486.jpg']
viewer_app = QtGui.QApplication(sys.argv)
ex = Example(url_list)
sys.exit(viewer_app.exec_())
view_image()
