The FirstIndex and the LastIndex properties define the indices of the Values that are currently being drawn in the chart.
Usually, these properties are equivalent to 0 for the FirstIndex and Values.Count-1 for the LastIndex. However, when the TRSChartPanel component has been zoomed, these properties reflect the point just before the first point in the zoomed area and the point just after the last point in the zoomed area (this ensures the visual aspect of the chart by allowing, for example, lines to be drawn into and out of the zoomed area. The FirstIndex and LastIndex properties provide more efficient access to only the values that are currently being drawn.
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For charts that don't have an easy visual ordering (such as a shape chart where depending on sizes things can overlap), the FirstIndex and LastIndex will be the entire Values collection. |
Namespace: FMX.RS.ChartPanel
Delphi |
public |
Property Value
Type: Integer
