【PyQt4 实例26】获得键盘事件

# -*- coding: utf-8 -*-
from PyQt4.QtGui import *
from PyQt4.QtCore import *
import sys
QTextCodec.setCodecForTr(QTextCodec.codecForName("utf8"))

class KeyEvent(QWidget):
    def __init__(self,parent=None):
        super(KeyEvent,self).__init__(parent)
        self.setWindowTitle(self.tr("获得键盘事件"))
        
        self.pix = QPixmap(self)
        self.pix.load("image/butterfly.png")
        self.image = QImage("image/butterfly.png")
        self.width = 400
        self.height = 300
        self.step = 2
        self.startX = 0
        self.startY = 0 
        self.resize(self.width,self.height)
        
    def drawPix(self):
        self.pix.fill(Qt.white)
        painter = QPainter(self.pix)
        pen = QPen(Qt.DotLine)
        painter.setPen(pen)
        for i in xrange(self.step,self.width,self.step):
            painter.drawLine(QPoint(i,0),QPoint(i,self.height))
        for j in xrange(self.step,self.height,self.step):
            painter.drawLine(QPoint(0,j),QPoint(self.width,j))
        painter.drawImage(QPoint(self.startX,self.startY),self.image)
    
    def keyPressEvent(self,event):
        if event.modifiers() == Qt.ControlModifier:
            if event.key() == Qt.Key_Left:
                self.startX = self.startX - 1 < 0 and self.startX or self.startX - 1
            if event.key() == Qt.Key_Right:
                self.startX = self.startX + 1 + self.image.width() > self.width and self.startX or self.startX + 1
            if event.key() == Qt.Key_Up:
                self.startY = self.startY - 1 < 0 and self.startY or self.startY - 1
            if event.key() == Qt.Key_Down:
                self.startY = self.startY + 1 + self.image.height() > self.height and self.startY or self.startY + 1
        else:
            self.startX = self.startX - self.startX%self.step
            self.startY = self.startY - self.startY%self.step
            
            if event.key() == Qt.Key_Left:
                self.startX = self.startX - self.step < 0 and self.startX or self.startX - self.step
            if event.key() == Qt.Key_Right:
                self.startX = (self.startX + self.step + self.image.width() > self.width ) and self.startX or self.startX + self.step
            if event.key() == Qt.Key_Up:
                self.startY = (self.startY - self.step < 0) and self.startY or self.startY - self.step
            if event.key() == Qt.Key_Down:
                self.startY = (self.startY + self.step + self.image.height() > self.height) and self.startY or self.startY + self.step 
            if event.key() == Qt.Key_Home:
                self.startX = 0
                self.startY = 0
            if event.key() == Qt.Key_End:
                self.startX = self.width - self.image.width()
                self.startY = self.height - self.image.height()
        self.drawPix()
        self.update()
    
    def paintEvent(self,event):
        painter = QPainter(self)
        painter.drawPixmap(QPoint(0,0),self.pix)
    
app=QApplication(sys.argv)
dialog=KeyEvent()
dialog.show()
app.exec_()