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TAChart: Fix divide-by-zero error in TBasicZoomTool in case of massive "over-zooming". Issue #40518.

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This commit is contained in:
wp_xyz 2023-09-26 11:57:46 +02:00
parent c76cc9ce62
commit 59f4113a9d
1 changed files with 14 additions and 5 deletions
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19
components/tachart/tatools.pas
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@ -1191,21 +1191,30 @@ procedure TBasicZoomTool.DoZoom(ANewExtent: TDoubleRect; AFull: Boolean);
procedure ValidateNewSize(LimitLo, LimitHi: TZoomDirection;
const PrevSize, NewSize, MaxSize, ImageMaxSize: Double; out Scale: Double;
out AllowProportionalAdjustment: Boolean);
var
SizeDiff, Half: Double;
begin
Scale := 1;
// if new size is only a bit different than previous size, this may be due to
// limited precision of floating-point calculations, so - if change in size
// is smaller than half of the pixel - set Scale to 0, disable proportional
// is smaller than half of the pixel - set Scale to 1, disable proportional
// adjustments and exit; in this case, change in size will be reverted for
// the current dimension, and adjusting the other dimension will be performed
// independently
if (NewSize > PrevSize * (1 - 0.5 / abs(ImageMaxSize))) and
(NewSize < PrevSize * (1 + 0.5 / abs(ImageMaxSize))) then begin
Scale := 0;
SizeDiff := (NewSize - PrevSize) * abs(ImageMaxSize);
Half := PrevSize * 0.5;
{ equivalent to:
NewSize-PrevSize 0.5 px
---------------- <--> --------------------
PrevSize abs(ImageMaxSize) px
}
if (SizeDiff > -Half) and (SizeDiff < Half) then
begin
AllowProportionalAdjustment := false;
exit;
end;
Scale := 1;
AllowProportionalAdjustment := true;
// if there is no both-sides extent limitation - allow change