This sample is for zooming with fixed Y-axis.
CrossRangeZoomer
zoomType: sets the desired axis for zoomming. (horizontal, vertical, both)
horizontalLabelFormatter: the formatter for the label of the horizontal line of crosshairs.
verticalLabelFormatter: the formatter for the label of the vertical line of crosshairs.
enableZooming: whether or not to use the zoom feature
enableCrossHair: whether or not to use crosshairs.
useDualCrossXLabel: whether or not to display two axes labels (it is available when dual axes are defined)
useDualCrossYLabel: whether or not to display two axes labels (it is available when dual axes are defined)
verticalLabelPlacement : the position for the label of the vertical line of crosshairs. (top, bottom)
horizontalLabelPlacement: the position for the label of the horizontal line of crosshairs. (left, right)

ā—¸Layout
<annotationElements>
	<CrossRangeZoomer zoomType="horizontal" horizontalLabelFormatter="{numFmt}"	
		enableZooming="true"/>
</annotationElements>