[Kst] extragear/graphics/kst/tests

[Adam Treat]

On Friday 13 October 2006 11:17 am, Adam Treat wrote:
> On Friday 13 October 2006 9:50 am, Barth Netterfield wrote:
> > I agree that this is what the code appears to be intending to do, and it
> > seems correct.  What is it actually doing?
> >
> > cbn
>
> Well, right now the code modifies the number of frames based on the value
> of Skip, but I think it does so incorrectly.  This is the current way and
> was committed by Andrew.  I think it is incorrect:
>
> 	new_nf = (new_nf/Skip)*Skip;
>
> In the testcase I described below, new_nf is initially equal to the
> frameCount of the datasource, ie 15.  All of those values are integers.
>
> In my view, this value should be equal to 11, ie the count from the first
> included frame to the last included frame.  Here is how I arrive at the
> value:
>
> 	new_nf = int((floor(double(fc - (new_f0 + 1)) / (double)Skip) *
> (double)Skip) + 1);
>
> Anyway, the point is we should come up with a set of testcases that we can
> all agree on.  I'd like to understand how you expect the numberOfFrames to
> vary according to the value of Skip and why.
>
> > On Friday 13 October 2006 03:55, Brisset, Nicolas wrote:
> > > > The skip frames tests currently fail for calculating the nf
> > > > and f0 in various scenarios.
> > > >
> > > > It seems my expectations for what skip will do differ from
> > > > the current implementation.  Consider the given testcase
> > > > where we have 15 items indexed from 0 to 14.  The RVector is
> > > > created with nf = -1 (readToEOF), f0 set to 0 (first frame)
> > > > and a skip value of 5.  I would expect that the result would
> > > > be a vector with 3 items {0, 5, 10}.  Item #14 does not fit
> > > > the the skip frame, thus the size of the vector is 3 and the
> > > > number of frames is 11 (the count of the items between 0 and
> > > > 10 inclusive).
> > >
> > > This is also what I expect. How about f0 = 2 for instance ?
>
> When reading from left to right (ie, readToEOF() or from f0 to NF) I would
> expect that f0 is never modified based on the value of Skip.  Instead, we'd
> modify nf based on the value of f0 and Skip.  We should respect that the
> user has set an initial starting frame and modify nf to the skip boundary
> based on that.
>
> When reading from right to left (ie, countFromEOF()) I suppose we should do
> the same but with f0 equal to the last frame in the file.

Err.. I was obviously wrong about countFromEOF()... Here is what I currently 
understand:

Given a file of 15 items, indexed 0-14... if I construct an rvector with:

Reqf0 = -1
ReqNF = 10
Skip = 5

then this should happen:

length = 2
item#0 = 5
item#1 = 10
numFrames = 6 (ie, the number of items inclusive)
startFrame = 5

no?

> Right now, the code modifies f0 AND nf.  I don't understand this behavior.
>
> Adam
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