PyQt：在 QPrinter 中使用 drawText 居中 QPainter 文本

Question

我正在尝试将文本集中在普通 A4 大小的作品集中，获得的尺寸是正确的，但它没有居中，我不知道是什么原因，这里我给你看代码

from PyQt4.QtGui import QPrinter,QPainter,QApplication
from PyQt4.QtCore import Qt,QRectF
import sys

app = QApplication(sys.argv)

printer = QPrinter()
painter = QPainter()

printer.setOutputFileName("prueba.pdf")
printer.setOutputFormat(QPrinter.PdfFormat)

printer.setPageMargins(0.0,0.0,0.0,0.0,1)
printer.setFullPage(True)
margin = printer.getPageMargins(1)
print margin
size = printer.paperSize(1)
width = size.width()
print width

painter.begin(printer)
painter.drawText(QRectF(0.0,0.0,width,50.0),Qt.AlignCenter|Qt.AlignTop,"abcdefghijklmn")
painter.end()

如您所见，我得到了对开类型点大小的宽度，并且将对开的整个宽度放置得不均匀

Answer 1

QPrinter 使用不同类型的units of measure：

QPrinter.Unit

此枚举类型用于指定页面和纸张尺寸的度量单位。

Constant  Value
QPrinter.Millimeter   0
QPrinter.Point        1
QPrinter.Inch         2
QPrinter.Pica         3
QPrinter.Didot        4
QPrinter.Cicero       5
QPrinter.DevicePixel  6

当您通过paperSize() 方法获取大小时，您要求以QPrinter.Point 为单位，但QPainter 使用以像素为单位的坐标，即QPrinter.DevicePixel，因此获得的宽度与宽度不同以像素为单位，如果我们只是改变测量单位的类型，如下所示：

app = QApplication(sys.argv)

printer = QPrinter()
painter = QPainter()

printer.setOutputFileName("prueba.pdf")
printer.setOutputFormat(QPrinter.PdfFormat)

printer.setPageMargins(0.0, 0.0, 0.0, 0.0, QPrinter.Point)
printer.setFullPage(True)
margin = printer.getPageMargins(QPrinter.Point)
print(margin)
size = printer.paperSize(QPrinter.DevicePixel)
width = size.width()
print(width)

painter.begin(printer)
painter.drawText(QRectF(0.0,0.0,width,50.0), Qt.AlignCenter|Qt.AlignTop, "abcdefghijklmn")
painter.end()