打印具有特定扩展名的文件

Question

我想打印使用文件选择器（或以某种方式）选择的文件某些扩展名，以便 PyQt 或打印机将自动识别格式（例如 pdf、ms word、excel、txt、html、jpg 等）

到目前为止，我已经找到here如何打印内容的 TextEdit，但我想打印各种格式的文件。

可以使用 PyQt5 还是我应该在别处搜索？

Answer 1

打印纯文本文档不需要 查看器，因为 print_() function actually calls the internal QDocument's print_() 函数：

filePath, filter = QFileDialog.getOpenFileName(self, 'Open file', '', 'Text (*.txt)')
if not filePath:
    return
doc = QtGui.QTextDocument()
try:
    with open(filePath, 'r') as txtFile:
        doc.setPlainText(txtFile.read())
    printer = QtPrintSupport.QPrinter(QtPrintSupport.QPrinter.HighResolution)
    if not QtPrintSupport.QPrintDialog(printer, self).exec_():
        return
    doc.print_(printer)
except Exception as e:
    print('Error trying to print: {}'.format(e))

您可能希望在实际打印之前添加一些功能来设置页面大小、文档页边距、字体大小等（只需阅读 QTextDocument 文档），我会把它留给您。

从 html 文件打印几乎相似，但您需要使用 QWebEnginePage class from QtWebEngineWidgets. See .
不要使用 QTextDocument.setHtml()，因为 Qt 对 html 标签的支持有限。

同样适用于 PDF 文件，不同之处在于文件必须通过 setUrl() and the QWebEngineSettings.PluginsEnabled setting has to be enabled through page.settings().setAttribute(setting, bool) 加载以防万一。
阅读有关 PDF File Viewing.

的文档

可以通过两种方法打印图像。

第一个也是更简单的方法是创建一个嵌入图像的临时 html 文件并加载到上面的网络引擎页面（您可以为 zoom/scaling 添加控件）。

或者，您可以直接使用 QPainter 打印，但您必须与打印机分辨率和图像大小相关，因此您可能希望在实际打印图像之前有一个预览对话框，否则可能太小（或太大）。

虽然比普通 <html><img src=""></html> 更复杂，但可以更好地控制图像 [s] 的定位和大小。

class ImagePrintPreview(QtWidgets.QDialog):
    def __init__(self, parent, printer, pixmap):
        super().__init__(parent)

        self.printer = printer
        self.pixmap = pixmap

        layout = QtWidgets.QGridLayout(self)

        self.viewer = QtWidgets.QLabel()
        layout.addWidget(self.viewer, 0, 0, 1, 2)

        self.resoCombo = QtWidgets.QComboBox()
        layout.addWidget(self.resoCombo, 1, 0)

        self.zoom = QtWidgets.QSpinBox(minimum=50, maximum=200, suffix='%')
        self.zoom.setValue(100)
        self.zoom.setAccelerated(True)
        layout.addWidget(self.zoom, 1, 1)
        self.zoom.valueChanged.connect(self.updatePreview)

        self.buttonBox = QtWidgets.QDialogButtonBox(
            QtWidgets.QDialogButtonBox.Ok|QtWidgets.QDialogButtonBox.Cancel)
        layout.addWidget(self.buttonBox)
        self.buttonBox.accepted.connect(self.accept)
        self.buttonBox.rejected.connect(self.reject)

        default = printer.resolution()
        self.resoCombo.addItem(str(default), default)
        for dpi in (150, 300, 600, 1200):
            if dpi == default:
                continue
            self.resoCombo.addItem(str(dpi), dpi)
        self.resoCombo.currentIndexChanged.connect(self.updatePreview)

        self.updatePreview()

    def updatePreview(self):
        # create a preview to show how the image will be printed
        self.printer.setResolution(self.resoCombo.currentData())
        paperRect = self.printer.paperRect(self.printer.DevicePixel)
        printRect = self.printer.pageRect(self.printer.DevicePixel)

        # a temporary pixmap that will use the printer's page size
        # note that page/paper are QRectF, they have a QSizeF which has to
        # be converted to a QSize
        pm = QtGui.QPixmap(paperRect.size().toSize())
        # new pixmap have allocated memory for their contents, which usually
        # result in some random pixels, just fill it with white
        pm.fill(QtCore.Qt.white)
        # start a qpainter on the pixmap
        qp = QtGui.QPainter(pm)
        # scale the pixmap to the wanted zoom value
        zoom = self.zoom.value() * .01
        scaled = self.pixmap.scaledToWidth(int(self.pixmap.width() * zoom), QtCore.Qt.SmoothTransformation)
        # paint the pixmap aligned to the printing margins
        qp.drawPixmap(printRect.topLeft(), scaled)

        # other possible alternatives:

        # Center the image:
        #   qp.translate(printRect.center())
        #   delta = QtCore.QPointF(scaled.rect().center())
        #   qp.drawPixmap(-delta, scaled)

        # To also rotate 90° clockwise, add this to the above:
        #   qp.rotate(90)
        # *after* qp.translate() and before qp.drawPixmap()


        # when painting to a non QWidget device, you always have to end the
        # painter before being able to use it
        qp.end()
        # scale the temporary pixmap to a fixed width
        self.viewer.setPixmap(pm.scaledToWidth(300, QtCore.Qt.SmoothTransformation))

    def exec_(self):
        if super().exec_():
            self.printer.setResolution(self.resoCombo.currentData())
            # do the same as above, but paint directly on the printer device
            printRect = self.printer.pageRect(self.printer.DevicePixel)
            qp = QtGui.QPainter(self.printer)
            zoom = self.zoom.value() * .01
            scaled = self.pixmap.scaledToWidth(int(self.pixmap.width() * zoom), QtCore.Qt.SmoothTransformation)
            qp.drawPixmap(printRect.topLeft(), scaled)
            # as above, that's important!
            qp.end()


class ImagePrinter(QtWidgets.QWidget):
    def __init__(self):
        super().__init__()
        layout = QtWidgets.QVBoxLayout(self)
        selBtn = QtWidgets.QPushButton('Open image')
        layout.addWidget(selBtn)
        selBtn.clicked.connect(self.selectFile)

    def selectFile(self):
        filePath, filter = QtWidgets.QFileDialog.getOpenFileName(self, 'Open file', '/tmp', 'Images (*.jpg *.png)')
        if not filePath:
            return
        pixmap = QtGui.QPixmap(filePath)
        if pixmap.isNull():
            return

        printer = QtPrintSupport.QPrinter(QtPrintSupport.QPrinter.HighResolution)
        if QtPrintSupport.QPrintDialog(printer, self).exec_():
            ImagePrintPreview(self, printer, pixmap).exec_()

请注意，我无法在 windows 下对此进行测试，因此可能需要更改与分辨率相关的内容（可能通过使用 printer.supportedResolutions()）。

如评论中所述，打印为其他（可能是专有）格式需要外部模块。

打印具有特定扩展名的文件

print a file with certain extension

python

python-3.x

qprinter

pyqt5