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Class: TContourPlot
Declaration: [1] procedure MarkAt (x,y: double; mk: byte);
[2] procedure MarkAt (x,y: integer; mk: byte);

The method MarkAt displays a symbol at the position [x,y] using the color DataColor. MarkAt can be drawn in two different coordinate systems: version [1] uses the world coordinates (these are the coordinates shown at the axes of the chart), version [2] uses the screen coordinates in pixels. Using screen coordinates has the effect that the mark remains at a fixed position even if the chart is panned or zoomed.

The shape of the symbol is defined by the parameter mk:

If the parameter mk is greater than MAXCANVASMARKS, a character corresponding to its ASCII code is displayed instead of a symbol. Digits can be drawn by setting mk to the codes 200..209 (200 = '0', 209 = '9').

Hint 1: Please note that some of the symbols are displayed by using pixel graphics. These symbols may be displayed in an unfavorable way (only tiny dots, or several thin lines) when using WMF for large printouts, i.e. for high resolution printers. The following symbols are affected:
    18  large shaded block
    25  large bold cross

Hint 2: In the Light Edition the number of chart elements (including all symbols) is restricted to 1000 elements.

Hint 3: Due to a bug in Delphi 2005 (.NET only) the filled symbols cannot be drawn correctly. This bug occurs only under the .NET environment, under Win32 the method MarkAt works as expected.

As of January 2005, there is no known work-around for this bug. If you need the full palette of symbols, you have to use Win32.

Hint 4: In order to select a symbol interactively you should use the component TMarkSel

Last Update: 2017-Sep-05