Codin' a HEX-Editor

[AGS]

Hi,

i decided to add a hex/asc viewing window to my tool. Scrolling with the keyboard or mousewheel works. But now I want to add scrollbar and have problems with calculating the propper pot, body, max values to set the scroller and also to set the hex/asc field pos correctly to what the scroller was scrolled to. I need help with the logic behind this idea.

Probably somebody around here has once solved this problem, so I ask. The difficulties are: when scrolling up or down with the bar the hex/asc content jumps horizontally, while I want it to jump only vertically. So if you are at pos. c0 for example, and scolling down, the pos value should also end with c0 and not with c2, c4, c6, c8 and so on.

Here is my approach to set pot, body and max of the scroller:

; window visible lines, 4 longs per line

move.w    gv_mon_lines(a4),d0
mulu.w    #16,d0
ext.l    d0
move.l    d0,oxPI_body(a1)

; set scroller pot to file offset

move.l    gv_offset(a4),oxPI_pot(a1)

; set scroller max to filesize

move.l    gv_size(a4),oxPI_max(a1)

And the other way, set the window content based on the scroller pos, when scrolled, d0 is pot value:

move.l    d0,gv_offset(a4)
add.l    gv_start(a4),d0
move.l    d0,gv_current(a4)

Somehow all this works, somehow not. The window content jumps around horizontally and yet if I resize the window sometimes the scroller draws partially off it's box (means, pot is too big).