image application ?????

[gui <gfenollera intelsis es>]

I have to make measurements of distance and angles in an image.
I know how to show my image with Imlib
I know clic in one point of  a draw_area and release the button in
another one and get the distance, drawing a line between the points
until the button is released, so
I want do both in the same window :-)
I need the velocity of imlib

Thanks a million
Guillermo