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LCL-GTK3: Fix Canvas.Line and Canvas.Rectangle artifacts. Issue #38741, patch from Anton Kavalenka.

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git-svn-id: trunk@65057 -
This commit is contained in:
juha 2021-04-23 15:34:09 +00:00
parent ef7d930ca6
commit eb9189fcac
1 changed files with 41 additions and 27 deletions
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68
lcl/interfaces/gtk3/gtk3objects.pas
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@ -1414,7 +1414,7 @@ begin
else
begin
w := FCurrentPen.Width;
if w = 0 then
if w <= 1 then
w := 0.5;
cairo_set_line_width(pcr, w {* ScaleX}); //line_width is diameter of the pen circle
end;
@ -2279,37 +2279,51 @@ end;
function TGtk3DeviceContext.LineTo(X, Y: Integer): Boolean;
var
FX, FY: Double;
X0, Y0: Integer;
X0, Y0,dx,dy:integer;
begin
if not Assigned(pcr) then
exit(False);
ApplyPen;
// we must paint line until, but NOT including, (X,Y)
// let's offset X, Y by 1 px, but only for horizontal and vertical lines (yet?)
cairo_get_current_point(pcr, @FX, @FY);
X0 := Round(FX-PixelOffset);
Y0 := Round(FY-PixelOffset);
if X0 = X then
begin
if Y = Y0 then
exit
else
if Y > Y0 then
Dec(Y)
else
Inc(Y);
end
else
if Y0 = Y then
begin
if X > X0 then
Dec(X)
else
Inc(X);
end;
cairo_line_to(pcr, X+PixelOffset, Y+PixelOffset);
if fCurrentPen.Width<=1 then // optimizations
begin
cairo_get_current_point(pcr, @FX, @FY);
X0:=round(FX);
Y0:=round(FY);
dx:=X-X0;
dy:=Y-Y0;
if (dx=0) and (dy=0) then exit;
if (dx=0) then
begin
cairo_move_to(pcr,X+PixelOffset,Y0);
cairo_line_to(pcr,X+PixelOffset,Y);
end else
if (dy=0) then
begin
cairo_move_to(pcr,X0,Y+PixelOffset);
cairo_line_to(pcr,X,Y+PixelOffset);
end else
if abs(dx)=abs(dy) then
begin
// here is required more Cairo magic
if (dx>0) then
begin
cairo_move_to(pcr,FX-PixelOffset,FY-PixelOffset);
cairo_line_to(pcr,X+2*PixelOffset, Y+2*PixelOffset);
end else
begin
cairo_move_to(pcr,FX+2*PixelOffset,FY);
cairo_line_to(pcr,X+PixelOffset, Y+PixelOffset);
end;
end else
cairo_line_to(pcr,X+PixelOffset, Y+PixelOffset);
end else
cairo_line_to(pcr,X+PixelOffset, Y+PixelOffset);
cairo_stroke(pcr);
Result := True;
end;
@ -2327,7 +2341,7 @@ begin
OldPoint^.X := Round(dx);
OldPoint^.Y := Round(dy);
end;
cairo_move_to(pcr, X+PixelOffset, Y+PixelOffset);
cairo_move_to(pcr, X{-PixelOffset}, Y{-PixelOffset});
Result := True;
end;