pixel location for LabelItem

[Pete Boysen]

I need to find the pixel location of a point to place a LabelItem on the graph. I see that in the Javascript there is a chart.getXAxis().translate(pt) but it is not part of the GWT api. Can you add it?

[Pete Boysen]

As a workaround I tried:
private native int getXPixel(JavaScriptObject chart,int pt) /-{
try {
return chart.plotLeft+chart.xAxis[0].translate(pt);
} catch(e) {
alert(e.message);
}
}-/;

and called getXPixel(chart.getNativeChart(),pt);

The problem is that I am trying to position a LabelItem based a point location. The above only works after the chart is rendered but the LabelItems don't appear if I call chart.setLabelItems after chart is rendered. What am I missing?

Also the above returns a number like 173.13455 when I expected an integer.

[Philippe Lhoste]

Indeed, I can confirm that LabelItems added after rendering are not displayed, even after a chart.redraw().

I think we can have a reasonable simulation of them with a function I found somewhere, using chart.renderer.text().

Funnily, I can't find translate() in the Highcharts reference, but I found a forum post (with jsFiddle example) using it, and indeed it is in the sources.
After some experimentations (new to JSNI stuff), I came up with a reasonable workaround.

private static native JavaScriptObject renderText(
      JavaScriptObject chart, String text,
      int plotX, int plotY
) /*-{
   return chart.renderer.text(text, plotX, plotY).add();
}-*/;
private static native double getXPos(JavaScriptObject chart, Number pt)
/*-{
   return chart.plotLeft + chart.xAxis[0].translate(pt);
}-*/;
private static native double getYPos(JavaScriptObject chart, Number pt)
/*-{
   return chart.plotTop + chart.plotHeight - chart.yAxis[0].translate(pt);
}-*/;

and in onClick() of chart.setClickEventHandler()'s anonymous class, I do:

        Point[] points = chartSeries.getPoints();
        JavaScriptObject nc = chart.getNativeChart();

        int posX = (int) getXPos(nc, points[count].getX());
        int posY = (int) getYPos(nc, points[count].getY());

        renderText(nc, "Point " + count, posX, posY);

You might want to add some offset to posX and posY to put them farther of the marker.

Note: at first, I tried int as return value, but the DevMode of GWT warned that it had to convert the Double return value to int...