Re: gEDA-dev: reverting a commit in a_pan.c:

[Peter Clifton <pcjc2@xxxxxxxxx>]

On Tue, 2008-04-01 at 11:29 +0200, Werner Hoch wrote:
> Hi Peter,

> I'll post a proposal how the switch to world coordinates should be done.

Excellent, I look forward to reading.

> > This said, looking over the patch, I suspect the distance may be
> > being set incorrectly if there is panning involved. Is that why
> > distance, loc_y and loc_x were set to zero in the old code? (Try
> > reverting to that behaviour for those variables).
> >
> > I'm away the rest of this week, but would obviously be interested in
> > a fix for this. Let me know what you find, or how to reproduce the
> > artifacts and I'll look at it when I'm back.
> 
> * put the center of a circle, 
> * zoom/pan,
> * move mouse
> 
> * set the first point of a rectangle
> * zoom/pan,
> * move mouse
> 
> Why this happens:
> The zoom/pan removes all rubber lines from the screen. 
> When moving the mouse the rubber function from the element erases that 
> rubber lines a second time with a XOR function, it becomes visible 
> again.
> Then the rubber lines are redrawn by the rubber function.

> In the net drawing code I've added a test to prevent this accidental 
> erase. In o_net_eraserubber:
> -------
>   if (! w_current->rubbernet_visible)
>     return;
> -------

> This kind of protection could be used for all object types.

Looking ahead to possible use of Cairo drawing, XOR isn't used at all.

Please let me have a look at a proposed fix though.

Best wishes,

-- 
Peter Clifton

Electrical Engineering Division,
Engineering Department,
University of Cambridge,
9, JJ Thomson Avenue,
Cambridge
CB3 0FA

Tel: +44 (0)7729 980173 - (No signal in the lab!)



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