PyQt print QWidget

Question

我试图按照文档打印QWidet，但遇到了一个错误。当我运行以下代码时，我得到了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((方法更改为以下方法，它确实有效(当然，我只是失去了缩放画家的所有能力(：

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

Answer 1

用于优化的QPainter不同时应用所有任务，但它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((方法或与其一起删除，因为destroyer也调用end(

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