Null value support for Chart for Xamarin Forms, so that if there is a null value, a line chart should appear "disconnected" at the point where the nulls are. Available in the R3 2018 SP release.
Currently the only way to apply different colors to the bars is through the ChartPalette. Provide an option to set the color according to the bound data item.
When you have a Chart with PieSeries and enable the SelectionBehavior - selecting a specific value makes it split from the pie chart and stand out. We should consider exposing another state, where the integrity of the pie chart is not broken and the selected items are just highlighted or probably have a bold border, etc.
The VisibleRange property can hold the actual visible minimum and maximum of the axis while the chart is being zoomed and panned.
If series' ItemsSource is a collection of objects implementing INotifyPropertyChanged, the chart should be automatically updated when an item is updated.
Using the RadPieChart and PieSeries (UI for Xamarin v2019.2.802.1 from NuGet), I can currently set the LabelBinding (or LabelFormat or LabelFormatter) to adjust the strings displayed in the labels on the slices of the pie chart, but unlike other chart controls, I currently have no way to modify the styling of those labels like I can in every other chart control I've used from Telerik UI for Xamarin.
It seems to me that it would be best to have more properties on the PieSeries class, like LabelFontSize, LabelFontAttributes, LabelFontFamily, LabelTextColor, and LabelMargin (Label prefix to distinguish from LegendTitleBinding could be kept or discarded as desired on some of these names).
LabelMargin would be particularly helpful to eliminate the UWP situation wherein currently all pie slice labels overlap with the outer lighter ring of the pie chart (see image from UWP). The others just seem needed to maintain a consistent appearance of charts within an app - if all my chart labels are dark blue and a different font size and style except for the not-style-able black labels in pie charts, that makes pie charts hard to incorporate without looking bad or forcing styling elsewhere to match the pie charts' fixed values.
When the chart has a lot of data, you may not necessarily want to show it all when the chart initially appears, but you may want to show the chart in a semi-zoomed state. Therefore, there should be properties which govern the ranges by which the chart should appear zoomed initially. So, the end-user should be able to zoom in/out starting from this state and then return to the same state if necessary (avoiding getting the whole data if he zooms out too much).
Allow easy exporting of a chart to a Xamarin.Forms image object. This will allow the images to be shared using social media.