LibHaru: How to draw a line of exact one inch

Question

Following is the code snippet I used to print a line of length 1 inch with the default DPI level(72dpi ).

page.moveTo(5, 20); page.lineTo(72, 20);

But when I take the printout, line is smaller than 1 inch. (around 2.24 cm instead of 2.54cm)