Selects a device to use for C1PrintDocument.MeasurementGraphics. This method looks for a printer with a "square" resolution (i.e. with the same horizontal and vertical DPI) equal to or larger than 300 DPI. If such a printer is found, it is assigned to C1PrintDocument.MeasurementPrinterName, and C1PrintDocument.MeasurementDevice is set to MeasurementDeviceEnum.Printer. Otherwise, C1PrintDocument.MeasurementDevice is set to MeasurementDeviceEnum.Screen. The selected device's resolution is returned by C1PrintDocument.MeasurementDpi.