More Chart Fixes

[oleibman]

Taking up where #2828 left off. Most of the following changes are demonstrated in 32readwriteChartWithImages1:

• Adds support for "scheme" colors (because rgb, theme, and index colors just weren't enough for Excel) for DataSeriesValues. See issue Define color of the marker on a chart #2299.
• For chart titles (including axis labels), rather than a font name, Excel supplies a 3-fold series of font names for Latin, East Asian, and Complex Scripts. New properties latin, eastAsian, and complexScript are added to the Font class. I frankly have no idea how, or even if, you can set these in Excel; my test case (sample 32readwriteScatterChart7) is a result of manually editing the XML.
• Add support for subscript/superscript to chart titles. This requires a new property baseLine in Font (positive=superscript negative=subscript baseline value says how high/low).
• Support for underscore with different scheme color than its text, using a new string property uSchemeClr in Font.
• Support for extra options for strikethrough, using a new string property strikeType in Font.
• Support for extra options for underscore type, using the existing string property underline in Font.
• I do not anticipate that any of the new Font properties will be used except for chart titles.
• If no default font overrides are found for a Rich Text element in chart titles, and no explicit font overrides are found for a Run under such an element, the font element of the Run is set to null.
• PhpSpreadsheet will always write a tag a:pPr and, underneath that, an empty tag a:defRPr, for default font settings for chart titles and axis labels. Combined with the previous bullet item, this will prevent PhpSpreadsheet from inadvertently overriding the Excel defaults (18 point bold Calibri for chart title, 10 point bold Calibri for axis labels).
• Axis labels will now be written to XML in the same manner as chart titles. Among other considerations, this means that they can now have colors. Fix Set color for xaxis / yaxis title #2700. Supersedes PR fix #2700 : set xaxis/yaxis and chart title color #2701. Demonstrated in sample 32readwriteStockChart5.

Fix #2817, preventing corruption of some scatter charts.

Fix corruption issue in Bubble Charts, and add support for 3D Bubble Charts. See issue #2763. Surface charts remain corrupted.

This is:

- [x] a bugfix
- [ ] a new feature
- [ ] refactoring
- [ ] additional unit tests

Checklist:

• Changes are covered by unit tests
  • Changes are covered by existing unit tests
  • New unit tests have been added
• Code style is respected
• Commit message explains why the change is made (see https://github.com/erlang/otp/wiki/Writing-good-commit-messages)
• CHANGELOG.md contains a short summary of the change
• Documentation is updated as necessary

Why this change is needed?

Provide an explanation of why this change is needed, with links to any Issues (if appropriate).
If this is a bugfix or a new feature, and there are no existing Issues, then please also create an issue that will make it easier to track progress with this PR.

[u01jmg3]

Sorry this is a late comment.

Just wondering if you could shed some light on one of your changes to Chart.php? I couldn't see any mention of it in your notes.

-$this->writeCategoryAxis($objWriter, $xAxisLabel, $id1, $id2, $catIsMultiLevelSeries, $xAxis, ($chartType === DataSeries::TYPE_SCATTERCHART) ? 'c:valAx' : 'c:catAx');
+$this->writeCategoryAxis($objWriter, $xAxisLabel, $id1, $id2, $catIsMultiLevelSeries, $xAxis);

It now means the (horizontal) X-axis is of the type "category" rather than "value" and I can see no way of being able to modify this within PHPSpreadsheet. If you were to create this chart from scratch in Excel it would apply the type "value".

[oleibman]

You are taxing my memory - I don't know that I can give you a satisfactory explanation. I started with known samples created in Excel, and the Xml for some of these contained multiple value axes and no category axes (or perhaps vice versa) when using scatter charts. If you have a workbook that, because of this code, winds up broken when you use PhpSpreadsheet to copy it to another worksheet, I can take a look. Please open a new issue if so.

[u01jmg3]

Thanks @oleibman - see issue #3294