Mapping an image onto a coordinate of TChart
lazarus / 55-TAChart

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sunbreezy393 · 2016-01-03 15:52

I was wandering if anyone would know how to map an image onto a
coordinate of a graph in TChart ?

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wp · 2016-01-03 19:12

What do you mean? Paint an image as a datapoint of a lineseries?
TLineSeries has a special event for this purpose: OnDrawPointer.
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 
DatapointImage: TBitmap;  BitmapFileName: string; procedure
TForm1.FormCreate(Sender: TObject);begin  DatapointImage :=
TBitmap.Create;  DataPointImage.Transparent := true; 
DatapointImage.LoadFromFile(BitmapFileName);end; procedure
TForm1.FormDestroy(Sender: TObject);begin 
DatapointImage.Free;end; procedure
TForm1.Chart1LineSeries1DrawPointer(ASender: TChartSeries;  ACanvas:
TCanvas; AIndex: Integer; ACenter: TPoint);begin  ACanvas.Draw(   
ACenter.X-DatapointImage.Width div 2,   
ACenter.Y-DatapointImage.Height div 2,    DatapointImage  );end;
This example uses a form with a chart and a lineseries. In the
lineseries, show the pointer by setting ShowPoints to true. Note that
the bitmap pointer is painted in addition to the standard data
pointer. So, if you want to hide the standard pointer, reduce its size
(or use the pointer style psPoint introduced some time ago), or set
its Brush.Style to bsClear and its Pen.Style to psClear. Depending on
the size of the image you may also want to increase to Margins of the
chart in order to avoid truncating of the images at the chart borders.