fix: Fix column width calculation logic in grid

[ericlln]

• Noticed this when testing some things on Enterprise. The column header “SPet500” in the stocks table is truncated when it shouldn’t be. For some reason this case didn’t occur on Core, perhaps due to slight differences in canvas configurations.
• Rounded down text measurement done in GridRenderer.binaryTruncateToWidth() as the measured text width with can differ slightly from the passed in estimated column width. This will prevent cases where text is truncated when it shouldn't be.

Stocks table for testing:

import deephaven.plot.express as dx
stocks = dx.data.stocks();

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 46.81%. Comparing base (35fc599) to head (ab245f5).
Report is 6 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2370      +/-   ##
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+ Coverage   46.80%   46.81%   +0.01%     
==========================================
  Files         710      710              
  Lines       39224    39243      +19     
  Branches     9789     9796       +7     
==========================================
+ Hits        18357    18370      +13     
- Misses      20856    20862       +6     
  Partials       11       11              

Flag	Coverage Δ
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[mofojed]

We should just set the font at the start of this method... Interesting that we weren't setting the font before this change, I wonder if that caused any issues.

[ericlln]

Yup missing that initially definitely caused issues and the header text width was not being calculated correctly as a result. Since the header font and cell font only differ slightly, it wasn’t able to be noticed visually. Again, it would be nice to be able to catch something like this through testing.

[mattrunyon]

Curious why we aren't just measuring the text with a cache like we already do in GridRenderer to determine if it needs to be truncated. I guess in theory this should reduce the number of measureText calls in the metric calculator (we will still measure the whole string in GridRenderer and might be faster if the values are constantly different where the cache isn't much help.

We could add a measured text cache to GridMetrics which is then accessible by GridRenderer and avoid double measuring the whole string. But that would be a separate ticket