* Some Fixes for Scatter Charts
Chart issues have been pouring in recently. This is a partial response to issue #2762. It implements "no joins" for scatter charts, as well as having the reader and writer handle "point size", "line width", and "color" for markers. A new boolean property `scatterLines`, with setter and getter, is added to DataSeriesValues to handle joins (default is true which means scatter plot points *are* joined by lines). Some, but not yet all, default font properties for the chart title are handled (color and, surprisingly, font name present challenges).
With these changes, sample 32readwriteScatterChart1.xlsx now looks closer to its source. There are still some differences (x-axis changes), but I think this change is already large enough. I can work on the other problems later.
The code for reading charts has not yet been converted to be namespace aware. Having a tiny island of aware code in a sea of unaware makes no sense to me, so some of the new code is likewise unaware. I hope to be able to get to it eventually, but, among other considerations, it is difficult to generate suitable test cases.
* Add Formal Tests
Essentially the same as the corresponding Samples, but with formal assertions.
* Clean Up Some Code in Reader/Xlsx/Chart
Having added code to support default font attributes as well as element-specific font attributes for chart captions, there was duplicated code between the default and specific sections. I hope that this PR makes the code easier to follow.
* Add Support for Font Name and Color to XLSX Chart Titles
XML layout for these in new files differs from what program was expecting. Not sure if program expectations were wrong, or if this is a change to Excel since initial development.
* Minor Improvement
Handle theoretical case where Chart title has text but no font information.
* Support Bezier Curve and Scaling of X-Axis on Scatter Plot
For Bezier, need to specify `<c:smooth>` tag in addition to already supplied `<c:scatterStyle val="smoothMarker">`
For X-Axis, scatter needs to supply both X and y axis as `<c:valAx>` rather than `<c:catAx>` for X.
Fix#2810. Repairing some Phpstan diagnostics, used `?:` rather than `??` in a few places.
2 different Html modules are affected. Also, Ods Reader, but its problem is with sheet title rather than cell contents. And, as it turns out, Ods Reader was already not handling sheets with a title of `0` correctly - it made a truthy test before setting sheet title. That is now changed to truthy or numeric. Other readers are not susceptible to this problem. Tests are added.
See #1285, which went stale and was closed, but recently received some positive feeback. It seems easy to implement, and the only other plaintext file format, Html, allows loading from a string. Those two reasons combined suggest that we should do it.
Drawings in an Xlsx file are stored in such a way that Php can read their contents using the `zip:` protocol. This does not, however, work when the file is read by PhpSpreadsheet and then saved as Html or Pdf, since the browser will not recognize that protocol even if the file is available. Such drawings need to be saved in the html as embedded images in order for the copy to display them properly. This is true even when the writer is set to not embed images (default).
An additional problem arises when an Html file with an embedded image is read, because `Worksheet\Drawing::setPath` attempts to validate the path, which it cannot do for the `data:image` Url which embedded images use.
And yet another problem. Writer/Html writes out a MemoryDrawing as a png using the imagepng function; but then declares it as jpeg in the Html. This is now corrected.
And a fourth problem. Writer/Html ignores the last row if it contains nothing but a Memory Drawing, which can be true when copying an Xls file.
These changes are testable (it's how I discovered the second part of this parlay). I think it is also useful to add a sample to see the results of this type of copy.
Mark Baker
oleibman
MarkBaker