Build 3.5.0.91 of xlsgen changes the default theme. It affects both new XLSX files (and their variants) as well as the rendering of charts by xlsgen.

The default theme is now Elemental, which is one of the 40 Office themes available in xlsgen.

To be more accurate, it uses Elemental for fonts and effects, but it uses the Adjacency theme colors. Indeed a theme is made of 3 independent sections : colors, fonts and effects, and a client application may choose a different theme for each section, among the 40 themes. The Elemental colors were shades of blue, and we believe it would be more appropriate to use a more diverse set of colors. That is why we choose Adjacency colors.

It is equivalent to writing the following in code, except you don't have to :

workbook.ThemeManager.Theme = workbooktheme_elemental;
workbook.ThemeManager.CustomColors = workbooktheme_adjacency;

It can be noted that this is just being the default and at any point in time in your client application, the theme can be modified by either choosing an entire theme (just one line of code), or a different theme for just colors, fonts or effects. For this there is this ThemeManager property available at the workbook level.

Most notably, if you would like to keep using the theme prior this change, all you have to do is add this line of code in your program :

workbook.ThemeManager.Theme = workbooktheme_modern;

The chart style itself for any new chart defaults on moderate effect with auto colors, which provides great looking shadow and soft edge effects. You can also go back to what it was before :

chart.Theme.EffectSpan = chartthemeeffectspan_none;
chart.Theme.ColorSpan = chartthemecolorspan_auto;


Below is a few charts rendered with the new default theme :