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Home ChartPack RChart Class TRChart Methods ZoomHistory
See also: ClearZoomHistory, MouseAction, MaxZoomStack, SetRange, ZoomStack, OnZoomPan, ConfineZoomRange, ConfineZoomRange (ContourPlot) 

ZoomHistory

Unit:SDL_rchart
Class: TRChart
Declaration: procedure ZoomHistory (Index: integer);

The method ZoomHistory allows to revert to a previous zoom state of the chart. Any changes of the chart ranges (either due to mouse actions or to programmatical changes) are recorded and stored in a circular stack of 16 (MaxZoomStack) elements. Therefore, the last 16 different setups are available by accessing this stack using the method ZoomHistory. The parameter Index may take any value between -15 and 0, referring to the oldest setup (Index = -15) up to the most recent one (Index = 0).

Note that setting the chart ranges by means of ZoomHistory does not (re)enter these settings into the zoom stack.

Example: This method is used in the following example program (see http://www.lohninger.com/examples.html for downloading the code): rchzoomp


Last Update: 2023-Dec-13