QT把widget转换成图片后打印

from PyQt5.QtWidgets import (QApplication, QWidget, QTableWidget,QPushButton,
                             QVBoxLayout,
                            QTableWidgetItem)
from PyQt5.QtGui import  QPixmap, QPainter, QImage, QTextDocument
from PyQt5.QtPrintSupport import  QPrinter, QPrintDialog, QPrintPreviewDialog
from PyQt5.QtCore import QRect, QPoint, QSize ,  Qt

def on_picButton_clicked():

    printer =QPrinter(QPrinter.HighResolution)
#/* 打印预览 */
    preview =QPrintPreviewDialog(printer,widget )   

    """
     * QPrintPreviewDialog类提供了一个打印预览对话框，里面功能比较全，
     * paintRequested(QPrinter *printer)是系统提供的，
     * 当preview.exec()执行时该信号被触发，
     * plotPic(QPrinter *printer)是用户自定义的槽函数，图像的绘制就在这个函数里。
    """
    preview.paintRequested.connect(plotPic)

    preview.exec(); #/* 等待预览界面退出 */

def  plotPic(printer):

    painter =QPainter(printer);
    image = QPixmap()

    image=widget.grab(QRect( QPoint( 0, 0 ),
                                            QSize( widget.size().width(),
                                                        widget.size().height()
                                                    )
                                        )
                                )# /* 绘制窗口至画布 */
   #QRect
    rect = painter.viewport();
   #QSize
    size = image.size();
    size.scale(rect.size(), Qt.KeepAspectRatio)#     //此处保证图片显示完整
    painter.setViewport(rect.x(), rect.y(),size.width(), size.height());
    painter.setWindow(image.rect());

    painter.drawPixmap(0,0,image); #/* 数据显示至预览界面 */

import sys

app = QApplication(sys.argv)
tablewidget = QTableWidget()
## 设置列数
tablewidget.setColumnCount(4)
tablewidget.horizontalHeader().setDefaultSectionSize(150)

## QStringList在PyQt5
header= ["name", "last modify time","type",  "size"]

tablewidget.setHorizontalHeaderLabels(header)
tablewidget.insertRow(0)
tablewidget.insertRow(0)

pItem1 =  QTableWidgetItem("aa" )
pItem2 =  QTableWidgetItem("bb" )
pItem3 =  QTableWidgetItem("cc" )
pItem4 =  QTableWidgetItem("dd" )
tablewidget.setItem( 0, 0, pItem1 )
tablewidget.setItem( 0, 1, pItem2 )
tablewidget.setItem( 0, 2, pItem3 )
tablewidget.setItem( 0, 3, pItem4 )

tablewidget.setMinimumSize(800, 600)

button = QPushButton('打印界面')
button.clicked.connect(on_picButton_clicked)

widget = QWidget()
layout = QVBoxLayout(widget)
layout.addWidget(button)
layout.addWidget(button_txt)
layout.addWidget(tablewidget)
widget.show()

sys.exit(app.exec_())