Best way to get a series screen X, Y for a certain value on the series?

[jep]

I'm working on implementing my own popup hint interaction (a lot more fancy than the ItemInfo one). I can get the screen X, Y from the gesture event using the event.pageX and event.pageY. I want to pop up a hint with a callout pointing to the point on the series. Unfortunately, pageX and pageY might be a few pixels off because you can click near the series point and not exactly on it.

So what I need to do is find what the ACTUAL series X, Y (in screen coordinates) are for a given X value in a series. Is there a way to do this? I'm digging around in the sprite code and thinking I may be finding undocumented ways to do this. But I'd prefer a way that's the most stable and doesn't rely on the guts of the code.

Any suggestions?

[jep]

Here's how I wound up doing it. Would still not mind hearing if there's a better "official" way so I'm leaving this with no answer marked.

This is code in the gesture event for an interaction:

        var item = this.getItemForEvent(e);
        if (item) {
            var chart = this.getChart();
            var chartRegion = chart.getMainRegion();
            var clientCoords = item.sprite.attr.matrix.transformPoint([
                item.series.getXAxis().getCoordFor(item.record.get(item.series.getXField())),
                item.series.getYAxis().getCoordFor(item.record.get(item.field))
            ]);
            var chartXY = chart.element.getXY();
            var seriesScreenX = clientCoords[0] + chartXY[0] + chartRegion[0];
            var seriesScreenY = chartRegion[3] - clientCoords[1] + chartXY[1] + chartRegion[1];

[jep]

Fixed the above so it works with category axes as well.