What units should the height and width be for a PHPExcel_Worksheet_Drawing_Object?

I'm generating an Excel file in PHP using the PHPExcel library. I am placing an image in the worksheet.

$objDrawing->setWidthAndHeight(100,100);

What are the dimenions 开发者_StackOverflow中文版of the height and width of the drawing object (is it %, pixels, mm, cm)?

Appreciate the help.

It's point.

1 point = 1/72 inches.
1 inch = 72 points
1 point = 0.035 centimeters ( or .35 millimeters )

Without checking, I believe that it's pixels, with an assumption of 72dpi when converting to Excel's rather quirky internal units.