Handling Chart Events

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Handling Chart Events


ZK Charts fire events when user is interacting with the chart, we can therefore declare a method to listen to the event and handle the event data.

ChartsEvent

ChartsEvent represents an event cause by user's interaction. If we want to shift the point's position when user clicks the bubble, we can listen the onPlotClick event and retrieve the point being clicked. Then update the point's position like below:

shift.zul

<window apply="ShiftComposer">
    <charts id="chart" type="bubble" />
</window>

ShiftComposer.java

public class ShiftComposer extends SelectorComposer<Window> {
    @Wire
    Charts chart;
    
    public void doAfterCompose(Window comp) throws Exception {
        super.doAfterCompose(comp);
        // initial series data
        initPoints();
        // hide some unnecessary options
        hideOptions();
    }
     
    @Listen("onPlotClick = #chart")
    public void shiftPoint(ChartsEvent event) {
        // retrieve the point object.
        Point point = event.getPoint();
        // shift the point by updating its x value.
        point.setX(point.getX().intValue() + random() / 10);
    }

    private void initPoints() {
        for (int i = 0; i < 10; i ++) {
            chart.getSeries(i).addPoint(random(), random(), i * 5);
        }
    }
 
    private void hideOptions() {
    	// remove chart title
    	chart.setTitle("");
        // remove y axis title
        chart.getYAxis().setTitle("");
        // hide the legend.
        chart.getLegend().setEnabled(false);
        // hide the tooltip.
        chart.getTooltip().setEnabled(false);
        // hide the exporting button.
        chart.getExporting().setEnabled(false);
    }
     
    private double random() {
        // returns random integer ranged from 10 to 100.
        return Math.round(((Math.random()) * 90 + 10));
    }
}

Congratulations! Now the user can interact with the chart. Here is what it shows:

File:PlotClickEventBefore.png

When user clicks the maroon bubble, the bubble will shift to the right a bit.

File:PlotClickEventAfter.png

Table of ChartsEvent and Description

EventName Description
onPlotClick Fires when the series is clicked, and it will pass the nearest point as a parameter.
onPlotCheckboxClick Fires when the checkbox next to the series' name in the legend is clicked.
onPlotLegendItemClick Fires when the legend item belonging to the series is clicked. (Not applicable to pies).
onPlotShow Fires when the series is shown after chart generation time, by clicking the legend item.
onPlotHide Fires when the series is hidden after chart generation time, by clicking the legend item.
onPlotMouseOver Fires when the mouse enters the graph.
onPlotMouseOut Fires when the mouse leaves the graph.
onPlotSelect Fires when selecting a point from a series.

The zkcharts doesn't send this event before you enable "point select" by Charts.getPlotOptions().getSeries().setAllowPointSelect(true); Reference: http://api.highcharts.com/highcharts#plotOptions.series.point.events

onPlotUnSelect Fires when unselecting a point from a series.
onPlotDrillUp Fires when drilling up from a drilldown series.
onPlotDrillDown Fires when a drilldown point is clicked, before the new series is added.

Note: see ChartsEvents for more details.

ClickEvent

What if we want to select the bubble and move it to the location where the mouse was clicked? It can be done by modifying the previous sample code as below:

    ...

    public void doAfterCompose(Window comp) throws Exception {
        super.doAfterCompose(comp);
        
        // initial series data
        initPoints();
        // hide some unnecessary options
        hideOptions();
        // allow point select
        chart.getPlotOptions().getBubble().setAllowPointSelect(true);
    }
     
    @Listen("onClick = #chart")
    public void movePoint(ChartsClickEvent event) {
    	for (Point point: chart.getSelectedPoints()) {
    		point.update(event.getXAxis(), event.getYAxis(), point.getHigh());
    		point.setSelected(false);
    	}
    }

    ...

Note: You can use ChartsClickEvent which extends MouseEvent to get the x and y axis values of where the mouse was clicked.

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Last Update : 2015/12/18

Copyright © Potix Corporation. This article is licensed under GNU Free Documentation License.