Pull Request Overview

This PR adds support for axis pointer update events to the HxEChart component, enabling external labels to display values when users hover over the chart. This functionality is required for a specific project requirement.

Key changes:

• Added OnAxisPointerUpdated event callback parameter to capture axis pointer movements
• Implemented JavaScript event handler with debouncing to handle 'updateAxisPointer' events
• Added C# method to invoke the event callback with the extracted data value

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 4 comments.

@JoseTheChamp @crdo

1. It's unclear what the double refers to here. As a component consumer, I can only assume it relates to the Value. Does this make sense for all chart types where updateAxisPointer is triggered?
2. We're discarding all the details provided by the original updateAxisPointer event (see apache/echarts-doc#230).

...we should use EChartAxisPointerUpdatedEventArgs, similar to how EChartClickEventArgs is used for the OnClick event. Resolving the Value from the event details is likely not the component's responsibility, but rather the caller's or something handled via an extension or helper method.

(The implementation proposed is appropriate simplification for a project-specific usage. Unfortunately, we decided to have HxEChart as an universal component and for such case we have to provide a more sophisticated solution.)

TBH, I'm not getting the idea behind List<EChartAxisPointerUpdatedEventArgs>.
According to apache/echarts-doc#230, the event itself holds this shape of data (does it?):

{
    "type": "updateaxispointer",
    "seriesIndex": 0,
    "dataIndexInside": 37,
    "dataIndex": 336,
    "axesInfo": [
        {
            "axisDim": "x",
            "axisIndex": 0,
            "value": 336
        },
        {
            "axisDim": "y",
            "axisIndex": 0,
            "value": 5188.092254685122
        },
        {
            "axisDim": "x",
            "axisIndex": 1,
            "value": 336
        }
    ]
}

Which means we should produce something like
EventCallback<EChartAxisPointerUpdatedEventArgs>:

public record EChartAxisPointerUpdatedEventArgs
{
    public int SeriesIndex { get; set; }
    public int DataIndexInside  { get; set; }
    public int DataIndex  { get; set; }
    public List<EChartAxisPointerUpdatedAxisInfo> AxesInfo  { get; } = new();
}
public record EChartAxisPointerUpdatedAxisInfo
{
   public string AxisDim  { get; set; }
   public int AxisIndex { get; set; }
   public object Value { get; set; }

   public T GetValue<T>()
}

The Value is already present in the event data or is it another value?
If it is another value than we need, I would prefer the consumer code or extension method to resolve the value in Blazor rather than the current JS approach (which seems a little scenario-bound).

see comments, adjusted on my own