在label中添加pixmap來顯示圖片時，當圖片過大時圖片顯示不全。
1.這時可以使用pixmap的scared（）方法，來設置圖片縮放。
QPixmap QPixmap.scaled (self, int w, int h, Qt.AspectRatioMode aspectMode = Qt.IgnoreAspectRatio, Qt.TransformationMode mode = Qt.FastTransformation)
Scales the pixmap to the given size, using the aspect ratio and transformation modes specified by aspectRatioMode and transformMode.
- If aspectRatioMode is Qt.IgnoreAspectRatio, the pixmap is scaled to size.
- If aspectRatioMode is Qt.KeepAspectRatio, the pixmap is scaled to a rectangle as large as possible inside size, preserving the aspect ratio.
- If aspectRatioMode is Qt.KeepAspectRatioByExpanding, the pixmap is scaled to a rectangle as small as possible outside size, preserving the aspect ratio.
If the given size is empty, this function returns a null pixmap.
In some cases it can be more beneficial to draw the pixmap to a painter with a scale set rather than scaling the pixmap. This is the case when the painter is for instance based on OpenGL or when the scale factor changes rapidly.
2.可以使用QLabel.setScaledContents (self, bool)方法來使pixmap自適應label大小
測試代碼：
#encoding:utf-8
'''
Created on 2016年7月10日
@author: Administrator
'''
from PyQt4.QtGui import *
from PyQt4.QtCore import *
import sys
class ImageFrame(QMainWindow):
def __init__(self):
super(ImageFrame, self).__init__()
self.initUI()
def initUI(self):
#窗體設置
self.setGeometry(100, 100, 500, 400)
self.setMaximumSize(500, 400)
self.setMinimumSize(500, 400)
self.setVisible(True)
self.statusBar()
image = QAction(QIcon('open.png'), 'open', self)
image.setShortcut('ctrl+o')
image.setStatusTip('open new image')
self.connect(image, SIGNAL('triggered()'), self.openImage)
toolbar = self.addToolBar('image')
toolbar.addAction(image)
label = QLabel()
label.setGeometry(0, 0, 400, 400)
self.setCentralWidget(label)
layout = QGridLayout()
self.label1 = QLabel()
self.label1.setGeometry(0, 0, 200, 200)
#設置label對齊方式
self.label1.setAlignment(Qt.AlignLeft)
button = QPushButton('edit')
edit = QLineEdit()
layout.addWidget(self.label1, 0, 0)
layout.addWidget(edit, 1, 0)
layout.addWidget(button, 1, 1)
label.setLayout(layout)
self.updataImage()
def openImage(self):
imageName = QFileDialog.getOpenFileName(self,"Open file dialog","/","jpg files(*.jpg)")
self.updataImage(imageName)
def updataImage(self, imageName = 'icon.png'):
pixmap = QPixmap(imageName)
'''圖像縮放:使用pixmap的scare方法，參數aspectRatioMode=Qt.KeepAspectRatio設置為等比例縮放，
aspectRatioMode=Qt.IgnoreAspectRatio為不按比例縮放'''
scaredPixmap = pixmap.scaled(400, 400, aspectRatioMode=Qt.KeepAspectRatio)
#圖像縮放：使用label的setScaledContents(True)方法，自適應label大小
#self.label1.setScaledContents(True)
print pixmap.height()
print pixmap.width()
self.label1.setPixmap(scaredPixmap)