Changing the horizontal grid line frequency in a Flex LineChart control using the horizontalChangeCount style

by Peter deHaan on November 15, 2007

in Charting, GridLines, LineChart

The following example shows how you can adjust the interval of horizontal grid lines in a LineChart by setting the horizontalChangeCount style.

Full code after the jump.

View MXML

<?xml version="1.0"?>
<!-- http://blog.flexexamples.com/2007/11/15/changing-the-horizontal-grid-line-frequency-in-a-flex-linechart-control-using-the-horizontalchangecount-style/ -->
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml"
        layout="vertical"
        verticalAlign="middle"
        backgroundColor="white">

    <mx:XMLListCollection id="dp">
        <mx:source>
            <mx:XMLList>
                <quote date="8/27/2007" open="40.38" close="40.81" />
                <quote date="8/24/2007" open="40.5" close="40.41" />
                <quote date="8/23/2007" open="40.82" close="40.6" />
                <quote date="8/22/2007" open="40.4" close="40.77" />
                <quote date="8/21/2007" open="40.41" close="40.13" />
                <quote date="8/20/2007" open="40.55" close="40.74" />
                <quote date="8/17/2007" open="40.18" close="40.32" />
                <quote date="8/16/2007" open="39.83" close="39.96" />
                <quote date="8/15/2007" open="40.22" close="40.18" />
                <quote date="8/14/2007" open="41.01" close="40.41" />
                <quote date="8/13/2007" open="41" close="40.83" />
                <quote date="8/10/2007" open="41.3" close="41.06" />
                <quote date="8/9/2007" open="39.9" close="40.75" />
                <quote date="8/8/2007" open="39.61" close="40.23" />
                <quote date="8/7/2007" open="39.08" close="39.42" />
                <quote date="8/6/2007" open="38.71" close="39.38" />
                <quote date="8/3/2007" open="39.47" close="38.75" />
                <quote date="8/2/2007" open="39.4" close="39.52" />
                <quote date="8/1/2007" open="40.29" close="39.58" />
            </mx:XMLList>
        </mx:source>
    </mx:XMLListCollection>

    <mx:ApplicationControlBar dock="true">
        <mx:Label text="horizontalChangeCount:" />
        <mx:HSlider id="slider"
                minimum="1"
                maximum="5"
                liveDragging="true"
                snapInterval="1" />

        <mx:Spacer width="100%" />

        <mx:Legend dataProvider="{lineChart}"
                direction="horizontal" />
    </mx:ApplicationControlBar>

    <mx:LineChart id="lineChart"
            showDataTips="true"
            dataProvider="{dp}"
            width="100%"
            height="100%">

        <mx:backgroundElements>
            <mx:GridLines direction="horizontal"
                    horizontalChangeCount="{slider.value}">
                <mx:horizontalStroke>
                    <mx:Stroke color="black" weight="0" alpha="0.2" />
                </mx:horizontalStroke>
            </mx:GridLines>
        </mx:backgroundElements>

        <!-- vertical axis -->
        <mx:verticalAxis>
            <mx:LinearAxis baseAtZero="false" title="Price" />
        </mx:verticalAxis>

        <!-- horizontal axis -->
        <mx:horizontalAxis>
            <mx:CategoryAxis id="ca" categoryField="@date" title="Date" />
        </mx:horizontalAxis>

        <!-- horizontal axis renderer -->
        <mx:horizontalAxisRenderers>
            <mx:AxisRenderer axis="{ca}" canDropLabels="true" />
        </mx:horizontalAxisRenderers>

        <!-- series -->
        <mx:series>
            <mx:LineSeries yField="@open" displayName="Open" />
        </mx:series>
    </mx:LineChart>

</mx:Application>

View source is enabled in the following example.

You can also change the horizontalChangeCount style using CSS, similar to the following snippet:

<mx:Style>
    GridLines {
        horizontalChangeCount: 2;
    }
</mx:Style>

Or you can change the horizontalChangeCount style using ActionScript, using the setStyle() method, similar to the following snippet:

myGridLines.setStyle("horizontalChangeCount", 2);

If you want to alternate background row colors in the LineChart, simply set the horizontalAlternateFill style, as seen in the following example:

View MXML

<?xml version="1.0"?>
<!-- http://blog.flexexamples.com/2007/11/15/changing-the-horizontal-grid-line-frequency-in-a-flex-linechart-control-using-the-horizontalchangecount-style/ -->
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml"
        layout="vertical"
        verticalAlign="middle"
        backgroundColor="white">

    <mx:Style>
        GridLines {
            horizontalChangeCount: 3;
            horizontalAlternateFill: white;
        }
    </mx:Style>

    <mx:XMLListCollection id="dp">
        <mx:source>
            <mx:XMLList>
                <quote date="8/27/2007" open="40.38" close="40.81" />
                <quote date="8/24/2007" open="40.5" close="40.41" />
                <quote date="8/23/2007" open="40.82" close="40.6" />
                <quote date="8/22/2007" open="40.4" close="40.77" />
                <quote date="8/21/2007" open="40.41" close="40.13" />
                <quote date="8/20/2007" open="40.55" close="40.74" />
                <quote date="8/17/2007" open="40.18" close="40.32" />
                <quote date="8/16/2007" open="39.83" close="39.96" />
                <quote date="8/15/2007" open="40.22" close="40.18" />
                <quote date="8/14/2007" open="41.01" close="40.41" />
                <quote date="8/13/2007" open="41" close="40.83" />
                <quote date="8/10/2007" open="41.3" close="41.06" />
                <quote date="8/9/2007" open="39.9" close="40.75" />
                <quote date="8/8/2007" open="39.61" close="40.23" />
                <quote date="8/7/2007" open="39.08" close="39.42" />
                <quote date="8/6/2007" open="38.71" close="39.38" />
                <quote date="8/3/2007" open="39.47" close="38.75" />
                <quote date="8/2/2007" open="39.4" close="39.52" />
                <quote date="8/1/2007" open="40.29" close="39.58" />
            </mx:XMLList>
        </mx:source>
    </mx:XMLListCollection>

    <mx:ApplicationControlBar dock="true">
        <mx:Label text="horizontalChangeCount:" />
        <mx:HSlider id="slider"
                minimum="1"
                maximum="5"
                liveDragging="true"
                snapInterval="1" />

        <mx:Spacer width="100%" />

        <mx:Legend dataProvider="{lineChart}"
                direction="horizontal" />
    </mx:ApplicationControlBar>

    <mx:LineChart id="lineChart"
            showDataTips="true"
            dataProvider="{dp}"
            width="100%"
            height="100%">

        <mx:backgroundElements>
            <mx:GridLines direction="horizontal"
                    horizontalChangeCount="{slider.value}">
                <mx:horizontalStroke>
                    <mx:Stroke color="black" weight="0" alpha="0.2" />
                </mx:horizontalStroke>
            </mx:GridLines>
        </mx:backgroundElements>

        <!-- vertical axis -->
        <mx:verticalAxis>
            <mx:LinearAxis baseAtZero="false" title="Price" />
        </mx:verticalAxis>

        <!-- horizontal axis -->
        <mx:horizontalAxis>
            <mx:CategoryAxis id="ca" categoryField="@date" title="Date" />
        </mx:horizontalAxis>

        <!-- horizontal axis renderer -->
        <mx:horizontalAxisRenderers>
            <mx:AxisRenderer axis="{ca}" canDropLabels="true" />
        </mx:horizontalAxisRenderers>

        <!-- series -->
        <mx:series>
            <mx:LineSeries yField="@open" displayName="Open" />
        </mx:series>
    </mx:LineChart>

</mx:Application>

View source is enabled in the following example.

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