Examples - XChartDemo->charts->date->DateChart03 - `Series`-colors and `Legend`-colors are confusing and might be misleading

[gibhub-src]

Hello guys,
I was reviewing the Demos and while figuring out and playing around with the #405 feature I realized that the DateChart03 has some misleading presentation. Here how it looks according to the original example with the YAxisTitles added:

The problem is, that in the Demo-code the "series 1" (assigned higher-range values AND created first) is explicitly created at position "1":

XChart/xchart-demo/src/main/java/org/knowm/xchart/demo/charts/date/DateChart03.java

Line 77 in b800f66

chart.addSeries("series1", xData1, yData1).setYAxisGroup(1);

before the "series 2" which should occupy position "0" (Zero Based).

XChart/xchart-demo/src/main/java/org/knowm/xchart/demo/charts/date/DateChart03.java

Line 78 in b800f66

chart.addSeries("series2", xData2, yData2);

Now if the code applies the "first"-Color to "series 2" it does NOT apply the same color to "series 2" in the Legend...or...the opposite. It might just assign the "first"-Color (i quess the Blue) to the "series 1" in the Legend, which is created first, but occupies position index "2".

Anyway, I think you get the idea from the illustration.
This just shows us, that the separate YAxis-Color #404 & #405 concept is quite reasonable.
Best Regards guys!

[gibhub-src]

Hm..as I debug the Y-data values (yData1, yData2) it seems like it relates them properly regardless which one is created first. It is just a color-mixing problem which we (currently) have to refer explicitly and might need to implement some mechanism to refer those colors-indexing implicitly.

I need you guys to review it.
Regards!

[Mr14huashao]

@gibhub-src
This situation is also considered normal. When adding a series, the lineColor of the series is not set. The lineColor of the series is set in turn from chart.getStyler().getSeriesColors().

Setting the series lineColor is the same as the group setting YAxisGroupTitleColor, so there is no confusion.

like this:

XYSeries series1 = chart.addSeries("series1", xData1, yData1);
series1.setYAxisGroup(1);
series1.setLineColor(chart.getStyler().getSeriesColors()[0]);
XYSeries series2 = chart.addSeries("series2", xData2, yData2);
series2.setLineColor(chart.getStyler().getSeriesColors()[1]);

chart.setYAxisGroupTitleColor(1, chart.getStyler().getSeriesColors()[0]);
chart.setYAxisGroupTitleColor(0, chart.getStyler().getSeriesColors()[1]);