OT: Re: problem with logic/math

["Eric M. Monsler" <emonsler beamreachnetworks com>]

Billy,

I can't tell from the code posted whether shiftX and shiftY refer to the 
center of the visible area, or not.  But, I suspect not, based on the 
fact that you need to adjust them as you scale.  I suspect that they 
represent the lower left corner, or something.

I suggest having the shiftX and shiftY refer to the unscaled coordinates 
of the center of the viewable area.  Then, they do not have to change on 
zooming in and out, the image is just redrawn with the same center.

If the redraw() would be a hassle to change, you may get acceptable 
visuals by just fixing the constants to be inverses of each other. 
Youve got 0.6 and 1.4, but 1/1.4 != 0.6.  Try (7.0/10.0) and (10.0/7.0), 
or something, and you should get closer.

One other change that you may want to make will be to adjust the shift 
quantity, currently "50", by the scaling.  I think that you probably 
want that change anyway, although I now see that if shiftX and shiftY 
are scaled, a constant would work.

Eric