在QPaintDevice的文档中(所有paintable-to实体都派生自，例如QWidget，QPixmap等)，有两个函数接收设备的DPIintlogicalDpiX()const;intphysicalDpiX()const;intlogicalDpiY()const;intphysicalDpiY()const;文档说ThelogicalDpiX()andlogicalDpiY()functionsreturnthehorizontalandverticalresolutionofthedeviceindotsperinch.ThephysicalDpiX()andphysi