How to use QPrinter and QPrintPreviewDialog

问题:

I want to preview, and then print, a report through a printer using PyQt. I tried the following code :

printer = QtGui.QPrinter()
doc  = QtGui.QTextDocument("testing")
dialog = QtGui.QPrintDialog(printer)
dialog.setModal(True)
dialog.setWindowTitle("printerrr")
pdialog = QtGui.QPrintPreviewDialog(printer)
pdialog.setWindowFlags(QtCore.Qt.Window)
pdialog.exec_()

How I can preview my report then print it?

回答1:

Basic demo of Qt's print dialogs:

PyQt4

import sys, os
from PyQt4 import QtGui, QtCore

class Window(QtGui.QWidget):
    def __init__(self):
        super(Window, self).__init__()
        self.setWindowTitle('Document Printer')
        self.editor = QtGui.QTextEdit(self)
        self.editor.textChanged.connect(self.handleTextChanged)
        self.buttonOpen = QtGui.QPushButton('Open', self)
        self.buttonOpen.clicked.connect(self.handleOpen)
        self.buttonPrint = QtGui.QPushButton('Print', self)
        self.buttonPrint.clicked.connect(self.handlePrint)
        self.buttonPreview = QtGui.QPushButton('Preview', self)
        self.buttonPreview.clicked.connect(self.handlePreview)
        layout = QtGui.QGridLayout(self)
        layout.addWidget(self.editor, 0, 0, 1, 3)
        layout.addWidget(self.buttonOpen, 1, 0)
        layout.addWidget(self.buttonPrint, 1, 1)
        layout.addWidget(self.buttonPreview, 1, 2)
        self.handleTextChanged()

    def handleOpen(self):
        path = QtGui.QFileDialog.getOpenFileName(
            self, 'Open file', '',
            'HTML files (*.html);;Text files (*.txt)')
        if path:
            file = QtCore.QFile(path)
            if file.open(QtCore.QIODevice.ReadOnly):
                stream = QtCore.QTextStream(file)
                text = stream.readAll()
                info = QtCore.QFileInfo(path)
                if info.completeSuffix() == 'html':
                    self.editor.setHtml(text)
                else:
                    self.editor.setPlainText(text)
                file.close()

    def handlePrint(self):
        dialog = QtGui.QPrintDialog()
        if dialog.exec_() == QtGui.QDialog.Accepted:
            self.editor.document().print_(dialog.printer())

    def handlePreview(self):
        dialog = QtGui.QPrintPreviewDialog()
        dialog.paintRequested.connect(self.editor.print_)
        dialog.exec_()

    def handleTextChanged(self):
        enable = not self.editor.document().isEmpty()
        self.buttonPrint.setEnabled(enable)
        self.buttonPreview.setEnabled(enable)

if __name__ == '__main__':

    app = QtGui.QApplication(sys.argv)
    window = Window()
    window.resize(640, 480)
    window.show()
    sys.exit(app.exec_())

PyQt5

import sys, os
from PyQt5 import QtCore, QtWidgets, QtPrintSupport

class Window(QtWidgets.QWidget):
    def __init__(self):
        super(Window, self).__init__()
        self.setWindowTitle('Document Printer')
        self.editor = QtWidgets.QTextEdit(self)
        self.editor.textChanged.connect(self.handleTextChanged)
        self.buttonOpen = QtWidgets.QPushButton('Open', self)
        self.buttonOpen.clicked.connect(self.handleOpen)
        self.buttonPrint = QtWidgets.QPushButton('Print', self)
        self.buttonPrint.clicked.connect(self.handlePrint)
        self.buttonPreview = QtWidgets.QPushButton('Preview', self)
        self.buttonPreview.clicked.connect(self.handlePreview)
        layout = QtWidgets.QGridLayout(self)
        layout.addWidget(self.editor, 0, 0, 1, 3)
        layout.addWidget(self.buttonOpen, 1, 0)
        layout.addWidget(self.buttonPrint, 1, 1)
        layout.addWidget(self.buttonPreview, 1, 2)
        self.handleTextChanged()

    def handleOpen(self):
        path = QtWidgets.QFileDialog.getOpenFileName(
            self, 'Open file', '',
            'HTML files (*.html);;Text files (*.txt)')[0]
        if path:
            file = QtCore.QFile(path)
            if file.open(QtCore.QIODevice.ReadOnly):
                stream = QtCore.QTextStream(file)
                text = stream.readAll()
                info = QtCore.QFileInfo(path)
                if info.completeSuffix() == 'html':
                    self.editor.setHtml(text)
                else:
                    self.editor.setPlainText(text)
                file.close()

    def handlePrint(self):
        dialog = QtPrintSupport.QPrintDialog()
        if dialog.exec_() == QtWidgets.QDialog.Accepted:
            self.editor.document().print_(dialog.printer())

    def handlePreview(self):
        dialog = QtPrintSupport.QPrintPreviewDialog()
        dialog.paintRequested.connect(self.editor.print_)
        dialog.exec_()

    def handleTextChanged(self):
        enable = not self.editor.document().isEmpty()
        self.buttonPrint.setEnabled(enable)
        self.buttonPreview.setEnabled(enable)

if __name__ == '__main__':

    app = QtWidgets.QApplication(sys.argv)
    window = Window()
    window.resize(640, 480)
    window.show()
    sys.exit(app.exec_())

EDIT

To print-preview a graphics view, use its render method:

def handlePreview(self):
    # dialog = QtPrintSupport.QPrintPreviewDialog() # PyQt5
    dialog = QtGui.QPrintPreviewDialog()
    dialog.paintRequested.connect(self.handlePaintRequest)
    dialog.exec_()

def handlePaintRequest(self, printer):
    self.view.render(QtGui.QPainter(printer))

回答2:

A PyQt5 update to the example by ekhumoro providing print preview and print for a Chart:

from PyQt5 import QtChart, QtCore, QtGui, QtPrintSupport, QtWidgets 
import sys
import random

class Window(QtWidgets.QWidget):
    def __init__(self):
        QtWidgets.QWidget.__init__(self)
        self.setWindowTitle(self.tr('Chart Printing'))
        self.chart = QtChart.QChart()
        self.chart_view = QtChart.QChartView(self.chart)
        self.chart_view.setRenderHint(QtGui.QPainter.Antialiasing)
        self.buttonPreview = QtWidgets.QPushButton('Preview', self)
        self.buttonPreview.clicked.connect(self.handle_preview)
        self.buttonPrint = QtWidgets.QPushButton('Print', self)
        self.buttonPrint.clicked.connect(self.handle_print)               
        layout = QtWidgets.QGridLayout(self)
        layout.addWidget(self.chart_view, 0, 0, 1, 2)
        layout.addWidget(self.buttonPreview, 1, 0)        
        layout.addWidget(self.buttonPrint, 1, 1)
        self.create_chart()

    def create_chart(self):
        self.chart.setTitle("Chart Print Preview and Print Example") 
        for i in range(5):     
            series = QtChart.QLineSeries()     
            series.setName("Line {}".format(i + 1))
            series.append(0, 0)
            for i in range(1, 10):
                series.append(i, random.randint(1, 9))
            series.append(10, 10)
            self.chart.addSeries(series)
        self.chart.createDefaultAxes() 

    def handle_print(self):
        printer = QtPrintSupport.QPrinter(QtPrintSupport.QPrinter.HighResolution)
        dialog = QtPrintSupport.QPrintDialog(printer, self)
        if dialog.exec_() == QtPrintSupport.QPrintDialog.Accepted:
            self.handle_paint_request(printer)

    def handle_preview(self):
        dialog = QtPrintSupport.QPrintPreviewDialog()
        dialog.paintRequested.connect(self.handle_paint_request)
        dialog.exec_()

    def handle_paint_request(self, printer):
        painter = QtGui.QPainter(printer)
        painter.setViewport(self.chart_view.rect())
        painter.setWindow(self.chart_view.rect())                        
        self.chart_view.render(painter)
        painter.end()

if __name__ == '__main__':
    app = QtWidgets.QApplication(sys.argv)
    window = Window()
    window.resize(640, 480)
    window.show()
    sys.exit(app.exec_())

Edit: For the above demo code to run on Windows, then it requires:

> pip install PyQt5  
> pip install pyqt5-tools   
> pip install PyQtChart