Flex: Positioning Plot Series item

I have a chart with multiple series (Area and Plot). The Area series has 'xField' as 'timeStamp' and 'yField' as 'price'. The Plot Series has 'xField' as 'timeStamp' and no 'yField'.... ! Can I position the plot series though I do not have a corresponding 'yField' value ? Can I assign a default value to the 'yField' (say '10' for all...?)

This is how I create my AreaChart initially. At this point, I have no idea whether to render events or not, so I do not attempt to create a 'plot series' at this point.

    //Note: 'AreaSeries' and 'PlotSeries' have different dataproviders
var areaChart:AreaChart = new AreaChart();
areaChart.width = width;
areaChart.height = height;
areaChart.showDataTips = true;

var vAxis:LinearAxis = new LinearAxis();
if(vAxisLblFunction != null){
    vAxis.labelFunction = vAxisLblFunction;
    areaChart.verticalAxis = vAxis;
}

var hAxis:CategoryAxis = new CategoryAxis();
hAxis.categoryField = "timeStamp";
areaChart.horizontalAxis = hAxis;
areaChart.horizontalAxisRenderer = createHAxisRenderer(hAxis);

var areaChartSeries:AreaSeries = new AreaSeries();
areaChartSeries.yField = "price";
areaChartSeries.displayName = "Stock Price";
areaChartSeries.setStyle("form", "segment");

var chartStroke:Stroke = new Stroke();
chartStroke.color = 0xFF0000;
chartStroke.weight = CHART_STROKE_WEIGHT;

var chartColor:SolidColor = new SolidColor();
chartColor.alpha = CHART_ALPHA;
chartColor.color = 0x000000;
areaChartSeries.setStyle("areaStroke", chartStroke);
areaChartSeries.setStyle("areaFill", chartColor);
chartSeriesArr.push(areaChartSeries);

Now, during run-time I want to plot some events as required.

var evtSer:PlotSeries = new PlotSeries();
evtSer.dataProvider = devEventsAC;  //Assume that I get the 'eventsDataProvider' somehow at run-time
evtSer.xField = "timeStamp";   //Notice there is no 'yField' to map here.
//evtSer.dataFunction = eventSerDataFunc;  //Tried with a 'dataFunction' assigning default value of '10' to the 'yField'

var fillColor:SolidColor = new SolidColor();
fillColor.color = 0xA933DC;
fillColor.alpha = 0.8;
evtSer.setStyle("fill", fillColor);

var strokeColor:SolidColorStroke = new SolidColorStroke();
strokeColor.color = 0x9494B8;
strokeColor.weight = 1;
evtSer.setStyle("stroke", strokeColor);
var chartSeriesArr:Array = trendPanel.areaChart.series;
chartSeriesArr.push(evtSer);
trendPanel.areaChart.series = chartSeriesArr;

So, my problem is that how do I plot the 'events' without a 'yField'. Is there a way to assign 'yField' value using the series's 'dataFunction' ?

Here is my thought:

1. In the 'dataFunction' we get a reference to the 'series' object. Using the series object get the 'parent' which is the chart and then get the series array for that chart.
2. Now, get the 'yField' value fron the 'AreaSeries' and return it as the 'yField' valu开发者_JAVA技巧e for the 'plot series'.
3. But, if I have multiple events with same 'yField' value there is a very good chance that all the events plotted top of each other. (First I am not sure whether 1 & 2 works here...)

Second approach is using the 'CartesianDataCanvas'. Again, here it requires datapoints (x,y) which I don't have.

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You can use the CartesianDataCanvas to draw stuff on a chart using data coordinates. But if you really want to use a PlotSeries to display time events on your chart, you can loop over your dataProvider and add a property with a default value that you will use in your plotSeries as an yField...