TAChart: CustomChartSource optimization
lazarus / 55-TAChart

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wp · 2011-09-04 15:08

Browsing through the source code of TAChart the following functions
got my attention:

Code: [Select]function TCustomChartSource.XOfMax: Double;
var
  i: Integer;
begin
  for i := 0 to Count - 1 do
    with Item[i]^ do
      if Y = Extent.b.Y then exit(X);
  Result := 0.0;
end;

function TCustomChartSource.XOfMin: Double;
var
  i: Integer;
begin
  for i := 0 to Count - 1 do
    with Item[i]^ do
      if Y = Extent.a.Y then exit(X);
  Result := 0.0;
end; 

Since Extent is a function iterating through all data items the XOfMin
and XOfMax function may be speeded up by storing the result of
Extent.a.Y in a local variable before entering the i loop.

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Ask · 2011-09-04 17:08

Caching should already be performed by the Extent function itself.

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wp · 2011-09-04 18:06

Fine.