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" title="" />
</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.update(point.getX().intValue() + random() / 10, point.getY());
    }
    
    private void initPoints() {
        for (int i = 0; i < 10; i ++) {
    	    chart.getSeries(i).addPoint(random(), random(), i * 5);
        }
    }

    private void hideOptions() {
        // 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);
        // Initialize series data
    }
    
    private double random() {
        // Returns random integer ranged from 0 to 100.
    	return Math.round((Math.random() * 100));
    }
}

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

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

Table of ChartsEvent and Description

EventName	Description
onPlotClick	Fires when the series is clicked.
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.
onPlotDrillUp	Fires when drilling up from a drilldown series.
onPlotDrillDown	Fires when a drilldown point is clicked, before the new series is added.

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:

    ...
    private Point selectedPoint; // Record selected point.
    ...
    @Listen("onPlotClick = #chart")
    public void selectPoint(ChartsEvent event) {
        // Retrieve the clicked point.
        Point point = event.getPoint();
        // Select the point if it haven't selected.
    	if (selectedPoint != point) {
    		selectedPoint = point;
    		selectedPoint.select();
    	}
    }
    
    @Listen("onClick = #chart")
    public void movePoint(ChartsClickEvent event) {
        // Do nothing if there is no selected point
        if (selectedPoint == null)
            return;
        // Move the selected point to the location where user clicked.
        selectedPoint.update(event.getXAxis(), event.getYAxis(), selectedPoint.getHigh());
        selectedPoint = null;
    }
    ....

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

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