Dynamically adding/removing TChartStye
lazarus / 55-TAChart

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mtanner · 2017-01-23 15:38

I'm drawing a stacked bat chart, with a single bar and a variable
number of "slices". So a bit like a pie chart but as a vertical
rectangle. I find I need to dynamically add TChartStyle items to the
TChartStyles component I am using. This seems necessary ij order to
get the legend having the correct number of entries. My problem is
that I cannot find the relevant "Clear" and "Add" methods for the
TChartStyles. Each time the chart is drawn I want to delete all styles
from the TChartStyles and then add a TChartStyle for eacj slice that I
am adding to the bar. Can you tell me the methods to do this please?

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wp · 2017-01-23 17:38

The TChartStyles component houses a collection named Styles which
contains all styles. Therefore, you simply call
ChartStyles1.Styles.Add to create a new ChartStyle and add it to the
collection. The Add method returns a pointer to the newly created
collectionitem; you must cast it TChartStyle to get access to its
properties. In order to delete a style just call the Delete method of
the collection with the index of the corresponding style
(ChartStyles1.Styles.Delete(index)):
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i var  style:
TChartStyle;...  style := TChartStyle(ChartStyles1.Styles.Add); 
style.Brush.Color := clBlue;  style.Text := 'Some legend text';... 
ChartStyles1.Styles.Delete(index_to_be_deleted);
In the attachment, there's a little demo which adds stacked bars at
runtime and allows deletion of the stack level selected in a listbox.

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mtanner · 2017-01-23 22:34

Thanks for that. All working fine now.

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wp · 2017-01-24 11:56

I added the demo to the examples coming with TAChart
(tachart/demo/runtime/chartstyles) so that it won't get buried in the
forum. Probably more to follow in the runtime folder...