Problems with date spans (for negative dates)

[chieffff]

When I initially load the timeline at zoom level 83, focusing the timeline at 3 m.e. bce , event with date "-3000000" is a few pixels too far to the left (at "-3039063 years" approximately).
When I try to change timescale using the slider, the situation is the same: event is some pixels too far to the left (for example "-3008010" instead of "-3000000" at zoom level 77).

WBR,
A. Sokoloff
Russia

[timeglider]

Thanks for filing this Alexander. This problem has been really vexing me.
Here's an attempt to at least understand the problem:

1. We use "seconds per pixel" to calculate positioning of events on the
   screen, based on the focus date. Basically, if the seconds per pixel is off
   by a small amount, the farther left or right of center an event is, the
   more it's off. If the "seconds per pixel" are off by just a tiny
   percentage, it adds up fast for dates in the billions.

So, at these larger dates, we're allotting too few "seconds per pixel"
----- so a when you calculate (event_date - focus_date / seconds per pixel)
the offset of the events, they're not shifting far enough to the left. I'm
experimenting with a correction to this (which is at about 1%) for dates
over 1 million years...

1. The second problem relates to how we, on the one hand, calculate pixel
   values from dates (related to problem multiple timelines bickering over who owns images, compressed tick marks... #1, with dates provided as
   YYYY-MM-DD, etc), and conversely, generate dates from pixel-values (or
   changes to pixel values), respecting pixel-value changes as one drags the
   timeline around. So there's a lack of total symmetry in the
   "date->seconds->pixels" and "pixels(->seconds)->date" algorithms.

I've gotten as far as evaluating the problem ------ I'll try to take it a
step farther in the coming week.

Michael

On Wed, Mar 14, 2012 at 5:16 AM, chieffff <
[email protected]

wrote:

When I initially load the timeline at zoom level 83, focusing the
timeline at 3 m.e. bce , event with date "-3000000" is a few pixels too
far to the left (at "-3039063 years" approximately).
When I try to change timescale using the slider, the situation is the
same: event is some pixels too far to the left (for example "-3008010"
instead of "-3000000" at zoom level 77).

WBR,
A. Sokoloff
Russia

---

Reply to this email directly or view it on GitHub:
#41

[chieffff]

Thank you!
I will wait and hope :)

[chieffff]

Hi! How are you?
Perhaps, there is a simple decision for my case?

[chieffff]

By the way, It's seems to me that "timeglider-event-spanners" are positioned almost precisely...