XFree86 tutorial?

Hi!

I am going to use XFree86 to enable my C program to set all properties a screen can have, i.e. resolution, frequency, horizontal and vertical sync and front and back porch, etc. Is there some good tutorial for teaching me how to do this? All information I have found is quite insufficient.

I have found some interesting functions though: XF86VidModeSwitchToMode, XF86VidModeModModeLine, XF86VidModeGetModeLine and XF86VidModeValidateModeLine. Also the very similar structs XF86VidModeModeLine and XF86VidModeModeInfo could be useful. I could try some trial and error, but I would really appreciate if there where some good learning resource. Thanks to those who know some. :)

You could look at the source of the xrandr client program.

Can I learn how to change refresh frequency, length of the vertical and horizontal signals and the front and back porch?

Frequency, definitely. I don't know what the other things are.

Source code to "xvidtune" is probably also useful.