2.1 Coordinate system and Unit of Measure

The PDF coordinate system origin is at the bottom left corner of the page. The X-axis is pointing to the right. The Y-axis is pointing in upward direction.

The PDF unit of measure is point. There are 72 points in one inch. The PDF File writer allows you to select your own unit of measure. All methods arguments representing position, width or height must be in your unit of measure. There are two exceptions: font size and resolution. Font size is always in points. Resolution is always in pixels per inch. The PDF File Writer converts all input arguments to points. All internal measurement values and calculations are done with double precision. At the final step when the PDF file is created, the values are converted to text strings. The conversion precision is six digits. The conversion formula used is:

// Value is Double
if(Math.Abs(Value) < 0.0001) Value = 0.0;
String Result = ((Single) Value).ToString();