Problem in RDLC Report printing directly to POS printer .

Question

Hello.
i am trying to print an RDLC Report Directly to a POS Printer, using source code from MSDN (Link), by exporting the report to (EMF) Image, then printing the image to the printer using PrintDocument,I calculate the height of the report based on number of rows (height of one row = 0.6 cm).
The problem is that when the report is too long (more than one page), I got its rows compressed to each other.
How to solve this problem ?
Do I have to use POS Printer library (.NET POS) instead of the exporting the report to image and printing the image? .

the source code is attached.