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LCL: Fix incorrect clipping by ellipse in TLazCanvas.

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(cherry picked from commit e3580cd0b0)
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wp_xyz 2023-06-27 15:53:56 +02:00 committed by Maxim Ganetsky
parent cb1b303b34
commit eda6b3c1df
1 changed files with 18 additions and 8 deletions
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26
lcl/lazregions.pas
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@ -164,17 +164,27 @@ end;
{ {
The equation of the inner area of an axis aligned ellipse: The equation of the inner area of an axis aligned ellipse:
(X/a)^2 + (Y/b)^2 <= 1 ((X-Xc)/a)^2 + ((Y-Yc)/b)^2 <= 1
where Xc = (X1 + X2)/2 and Yc = (Y1 + Y2)/2 (ellipse center
and a = (X2 - X1)/2 and b = (Y2 - Y1)/2 (half axes)
or:
((2 X - (X1+X2)) / (X2-X1))^2 + ((2 Y - (Y1+X2)) / (Y2-Y1))^2 <= 1
} }
function TLazRegionEllipse.IsPointInPart(AX, AY: Integer): Boolean; function TLazRegionEllipse.IsPointInPart(AX, AY: Integer): Boolean;
var
a, b: Integer;
begin begin
a := X2 - X1; if (X2 < X1) or (Y2 < Y1) then
b := Y2 - Y1; Result := false
if (a < 0) or (b < 0) then Exit(False); else
if (X1 = X2) then
Result := Sqr(AX/a) + Sqr(AY/b) <= 1; Result := (AX = X1) and (AY >= Y1) and (AY <= Y2)
else
if (Y1 = Y2) then
Result := (AY = Y1) and (AX >= X1) and (AX <= X2)
else
Result := sqr((AX*2 - (X2+X1)) / (X2-X1)) + sqr((AY*2 - (Y1+Y2)) / (Y2 - Y1)) <= 1;
end; end;
{ TLazRegionPart } { TLazRegionPart }