转载：
https://www.cnblogs.com/daniaofighter/p/5713127.html
在label中添加pixmap来显示图片时，当图片过大时图片显示不全。
1.这时可以使用pixmap的scared（）方法，来设置图片缩放。
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)方法来使pixmap自适应label大小
测试代码：
#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):
#窗体设置
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)
#设置label对齐方式
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)
”’图像缩放:使用pixmap的scare方法，参数aspectRatioMode=Qt.KeepAspectRatio设置为等比例缩放，
aspectRatioMode=Qt.IgnoreAspectRatio为不按比例缩放”’
scaredPixmap = pixmap.scaled(400, 400, aspectRatioMode=Qt.KeepAspectRatio)
#图像缩放：使用label的setScaledContents(True)方法，自适应label大小
#self.label1.setScaledContents(True)
print pixmap.height()
print pixmap.width()
self.label1.setPixmap(scaredPixmap)