Document some cases where solution might not work well. Making class extendable and offering some over-rideable methods may allow for solutions to some of these problems.
Fix#4416. A peculiar problem indeed. PhpSpreadsheet has been considering a column to be filtered if any cell in the column is filtered and does not preserve the column width if that is the case. It should consider the column not filtered if any cell in the column is not filtered, and consider it filtered only if there are no cells to which that applies. At least, that's how I think it should work, and this change doesn't break any existing tests, and solves this issue.
It flagged a statement as dead code. It was correct - there was a typo in the variable name. But no tests had failed. The explanation was, of course, that this particular path was not adequately tested.
PhpSpreadsheet extends Excel (dating back to PHPExcel) by allowing the ordinal form of days in the DATE function, implemented as "take the numeric portion if the field is a string consisting of a numeric portion followed by some alphabetics". Whether or not this is a good idea, it would be a breaking change to eliminate it, so that's not going to happen. However, the same logic has been applied to month, and I don't see a use case for that, so I'm eliminating it - any non-numeric string used as the month parameter will now result in a VALUE error. It also turns out that Excel accepts null, false, and true for the month, and PhpSpreadsheet will now do likewise.
Spreadsheet clone already copies Calculation instanceArrayReturnType property. It should also copy some other Calculation instance properties, namely suppressFormulaErrors, calculationCacheEnabled, and branchPruningEnabled.
Helper/TextGrid was intended to assist with some samples. However, it has emerged recently on two tickets. PR #4342 intended to introduce functionality very similar to TextGrid, and was closed for that reason. Issue #1640 was closed as stale over 4 years ago, despite the fact that TextGrid seems an adequate resolution for it.
Since it seems that there is a use for this function beyond its original intended usage, I added a few parameters to give it some flexibility - the ability to omit row and/or column headers, and the ability to add a divider line between rows.
A description of this function is added to the formal documentation.
Fix#4415. We store the rarely-used property Drawing/Shadow/Alpha as an integer representing the percentage. Excel also stores it as an integer, but multiplies it by 1,000, so we divide by 1,000 when we read this value. This can, and in the case of the issue at hand does, leave a fractional portion. Php has deprecated passing a float with a fractional portion to an int argument, so the reporter saw a deprecation message. This is easily fixed.
Fix#4411. User copied some code from a PHPExcel program which set DisplayAsBlanks to `0`. This resulted in what Excel deemed a corrupt spreadsheet using PhpSpreadsheet. The only values allowed for that field are `gap`, `zero` (not `0`), and `span`. PHPExcel used `0` as a default, and got away with it because it ignored the value entirely when writing out the spreadsheet, using `gap` all the time.
I had to choose between throwing an exception and just using the default when an attempt is made to set that property to an invalid value. An exception just seems more punitive than helpful to me, especially if we want people to migrate from PHPExcel, which still seems to have a large user base. So I've gone with using `gap` in place of an invalid value. Note that, according to https://learn.microsoft.com/ru-ru/openspecs/office_standards/ms-oe376/b5c5c694-21d9-437c-9a4a-21e0e843eed8, `gap` is used as the default whenever it is permitted for the chart in question; and, when it isn't permitted, the chart will use its default method (which will always be `zero`).
There were no tests nor samples for this property. All the tests and samples which use it use only `gap`. I have added a small test, and a new sample to illustrate the difference between the 3 options.
See discussion #4202. Users can extend Spreadsheet, but the readers cannot return the extended class. This is solved pretty easily by adding a protected method in BaseReader which returns a new Spreadsheet. Users can then extend the Reader which they want, overriding that method to return the extended class.