Test failure on some Windows systems with 125% display scaling, Chart2ImportTest::testAutomaticSizeBarChartVeryLongLabel

[Regina Henschel]

Hi Ilmari,

Ilmari Lauhakangas schrieb am 19.11.2022 um 15:41:
> A new dev is seeing this test failure on Windows with 125% scaling, the 
> test passes if scaling is set to 100%:
> 
> C:/cygwin/home/Client/lode/dev/core/chart2/qa/extras/chart2import.cxx(2273) 
> : error : Assertion
> Test name: Chart2ImportTest::testAutomaticSizeBarChartVeryLongLabel
> double equality assertion failed
> - Expected: 5320
> - Actual  : 4765
> - Delta   : 100

Yes that is a common problem for me. I usually work with 125%, but need 
to switch to 100% only to test, whether I have produced the problem with 
my patch or not.

> 
> Mike added tolerance to this test in 
> 09e499e64ec4acb24c9524c8aacabc6182124442 but in this case the difference 
> seems surprisingly large.

Critical are tests using BoundRect. A tolerance helps sometimes, I guess 
in cases where it matters how large the last included pixel is.

In this case a tolerance is no solution. The text box which is generated 
by the automatic indeed differs between 96 dpi and 120 dpi, see attached 
screenshots. One has six, the other has seven words in the line.

We can fix the test itself or restrict it to 96dpi. Or fix the automatic 
that layouts labels.

There exist more of such tests, but I have not made up a list of such 
test. Perhaps something to discuss in ESC, how to treat such dpi 
depending tests.

Kind regards,
Regina
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