[vtk-developers] Charts regressions

[Marcus D. Hanwell]

On Sun, Oct 17, 2010 at 3:24 PM, Bill Lorensen <bill.lorensen at gmail.com>wrote:

> Sorry, I did mean to send this to arb at vtk.org. gmail was overly agressive.
>

Do you mean you didn't mean to send this to arb at ...? I was wondering why it
was an ARB issue.

>
> Marcus,
>
> I noticed a while back on the wiki examples that the y axis label does
> not fit on the window for vtk charts. I'm not sure when this
> regression occurred since we don't update VTK every night.
>

I remember you emailing me about this, and I gave you an overview of what I
was doing at the time. Due to my travel schedule, and some other events, my
topic branch to address this has been a little delayed. I had most of it
staged last week, but was working on fixing a few more regressions before
merging it. I think I got most of it finished yesterday.

>
> I looked at the VTKData git repository. On 8/23, many Charts baselines
> were changed.
>
> Please compare this baseline:
>
> http://vtk.org/gitweb?p=VTKData.git;a=blob;f=Baseline/Charts/TestScatterPlot.png;hb=e293ebc8db06c21a574f42911b27b9b8c92c6a95
> with this baseline
>
> http://vtk.org/gitweb?p=VTKData.git;a=blob;f=Baseline/Charts/TestScatterPlot.png;hb=fcdb83896ab1de8ec8efcb10bf5a079f2c7219f7
>
> The former looks correct to me. The Y-Axis lies completely in the
> window, while the later looks wrong to me. The Y-Axis label is
> truncated.
>

The problem is that it was only correct for short strings, for longer ones
they would still fall off the edge. The newer code uses font metrics to
determine the chart layout and works for all font sizes and string lengths.
The issue was that only the Qt label render strategy was respecting the
rotation, but the freetype strategy was returning the wrong metrics and not
rotating the font.

>
> This occurs consistently on all of the baselines that hav ea Y-Axis labe;.
>
> It looks a lot better when using the Qt label render strategy, and as I
said I was working on getting this into shape with the freetype rendering
(which is default for most VTK applications. The StringToImage topic branch
contains a lot of these changes, and there are a few more I will push
shortly and integrate tomorrow.

I didn't want to cause all of the baseline images to need multiple updates,
but once I merge the changes in tomorrow many tests will require updates. I
think the new baselines look far better, and I am hoping to land some more
string rendering improvements in master over the next few weeks. I did not
intend to leave the axis rendering like this for a release.

I hope that clears things up, these changes would have likely made it in
last week if it weren't for some other large changes also being integrated
along with some other timing issues.

Marcus
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