The scripts based on the Arabic alphabet are cursive and their characters are dynamically variable. These characteristics of such scripts need changes in the fonts conception. As a consequence of the cursivity, the representation of Arabic characters in outlines may be different of those concerning the Latin ones. The characters dynamic variability can be materialized through the stretchability of some characters in both the vertical and horizontal directions, at the same time, when justifying lines for instance. In order to get texts written with stretchable characters, represented as outlines, some curves intersections, among the curves composing the characters outlines, are to be determined dynamically. The Postscript procedure to produce a dynamic character, in a dynamic font, is repeated whenever the letter is to draw. So, the determination of the curves intersections coefficients in the procedure, applying an iterative algorithm is of a high cost. A new method for developing an optimal font is to find out. In this paper, a method based on the curves comparison is presented. It allows the determination of the characters with eventually overlapping outlines. Then, a way to approximate the curves intersections coefficients is given. This is enough to remove overlapping in outlines.