PyQt打印QWidget。

Question

PyQt打印QWidget。

5

我正在尝试按照打印QWidget 的文档进行操作，但是出现了错误。当我运行以下代码时，会提示QPaintDevice: Cannot destroy paint device that is being painted。

import sys
from PyQt4 import QtGui, QtCore

class SampleApp(QtGui.QDialog):
    def __init__(self):
        super().__init__()

        layout = QtGui.QVBoxLayout()
        self.setLayout(layout)

        text_editor = QtGui.QTextEdit()
        layout.addWidget(text_editor)

        button = QtGui.QPushButton("Print")
        layout.addWidget(button)
        button.clicked.connect(self.print_me)

    def print_me(self):
        printer = QtGui.QPrinter()
        printer.setOutputFormat(QtGui.QPrinter.PdfFormat)
        printer.setOutputFileName("Test.pdf")

        self.painter = QtGui.QPainter(printer)
        margins = printer.getPageMargins(QtGui.QPrinter.DevicePixel)
        xscale = (printer.pageRect().width() - margins[0]) / self.width()
        yscale = (printer.pageRect().height() - margins[1]) / self.height()
        scale = min(xscale, yscale)
        self.painter.scale(scale, scale)

        self.render(self.painter)

app = QtGui.QApplication(sys.argv)
ex = SampleApp()
ex.show()
sys.exit(app.exec_())

如果我将print_me()方法更改为以下内容，则它会起作用（当然，我失去了所有缩放绘图器的能力）：

def print_me(self):
    printer = QtGui.QPrinter()
    printer.setOutputFormat(QtGui.QPrinter.PdfFormat)
    printer.setOutputFileName("Test.pdf")

    self.render(QtGui.QPainter(printer))

- Spencer

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- eyllanesc · Accepted Answer

QPainter用于优化时并不同时执行所有任务，而是保留指令，并在最后应用它们，但为了强制执行该任务，最好调用end()方法或将其与delete一起使用，因为销毁器也会调用end()。另外，QPainter不必是类的成员：

def print_me(self):
    printer = QtGui.QPrinter()
    printer.setOutputFormat(QtGui.QPrinter.PdfFormat)
    printer.setOutputFileName("Test.pdf")

    painter = QtGui.QPainter(printer)
    xscale = printer.pageRect().width() / self.width()
    yscale = printer.pageRect().height() / self.height()
    scale = min(xscale, yscale)
    painter.translate(printer.paperRect().center())
    painter.scale(scale, scale)
    painter.translate((self.width() / 2) * -1, (self.height() / 2) * -1)

    self.render(painter)
    painter.end()
    # or
    # del painter