tachart/tutorials/mandelbrot
lazarus / 55-TAChart

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kiyo · 2025-06-02 02:45

I am using Windows version .
have compiled the following project:
C:/lazarus/components/tachart/tutorials/mandelbrot
however
Zoom with mouse left-drag does not work.
Please let me know the cause and solution.

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wp · 2025-06-02 07:59

Thanks for reporting. It seems that something broke it between v2.2.6
and v3.0.0...

[EDIT]
Found it - it was caused by some optimization more than two years ago.
Is fixed in Laz/main and /fixes (i.e. will be included in v.4.2). If
you want to fix your current version open file tagraph.pas from folder
components/tachart of your Lazarus installation. Find the
implementation of TChart.SetLogicalExtent. Insert "FOldClipRect :=
ZeroRect" before the line "FLogicalExtent := AValue"

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 procedure
TChart.SetLogicalExtent(AValue: TDoubleRect);var  AllowChange:
Boolean;  w, h: Double;begin  [...]  if FLogicalExtent = AValue then
exit;  w := Abs(AValue.a.X - AValue.b.X);  h := Abs(AValue.a.Y -
AValue.b.Y);  with ExtentSizeLimit do    if      UseXMin and (w <
XMin) or UseXMax and (w > XMax) or      UseYMin and (h < YMin) or
UseYMax and (h > YMax)    then      exit;  FOldClipRect := ZeroRect; 
FLogicalExtent := AValue;  FIsZoomed := true;  StyleChanged(Self);end;
Then do the same in TChart.ZoomFull:
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 procedure
TChart.ZoomFull(AImmediateRecalc: Boolean);begin  if AImmediateRecalc
then    FLogicalExtent := GetFullExtent;  if not FIsZoomed then exit; 
FIsZoomed := false;  FOldClipRect := ZeroRect;  Invalidate;end;

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kiyo · 2025-06-03 10:05

Thank you for your prompt response
I confirmed that the issue has been resolved in Lazarus 4.0.