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carbon: final fixes for LineTo 1-pixel line drawing

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git-svn-id: trunk@27048 -
This commit is contained in:
dmitry 2010-08-10 08:39:10 +00:00
parent 9a8d703529
commit 14b1813403
1 changed files with 27 additions and 25 deletions
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52
lcl/interfaces/carbon/carboncanvas.pp
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@ -1195,42 +1195,44 @@ end;
------------------------------------------------------------------------------}
procedure TCarbonDeviceContext.LineTo(X, Y: Integer);
var
deltaX, deltaY, absDeltaX, absDeltaY, clipDeltaX, clipDeltaY: Float32;
deltaX, deltaY, absDeltaX, absDeltaY: Integer;
clipDeltaX, clipDeltaY: Float32;
tx,ty:Float32;
begin
deltaX := X - PenPos.x;
deltaY := Y - PenPos.y;
if (deltaX=0) and (deltaY=0) then Exit;
absDeltaX := Abs(deltaX);
absDeltaY := Abs(deltaY);
if absDeltaX > absDeltaY then
if (absDeltaX<=1) and (absDeltaY<=1) then
begin
if deltaX > 0 then clipDeltaX := -1.0 else clipDeltaX := 1.0;
clipDeltaY := clipDeltaX * deltaY / deltaX;
// special case for 1-pixel lines
tx := FPenPos.x + 0.55;
ty := FPenPos.y + 0.55;
end
else
begin
if deltaY > 0 then clipDeltaY := -1.0 else clipDeltaY := 1.0;
clipDeltaX := clipDeltaY * deltaX / deltaY;
// exclude the last pixel from the line
if absDeltaX > absDeltaY then
begin
if deltaX > 0 then clipDeltaX := -1.0 else clipDeltaX := 1.0;
clipDeltaY := clipDeltaX * deltaY / deltaX;
end
else
begin
if deltaY > 0 then clipDeltaY := -1.0 else clipDeltaY := 1.0;
clipDeltaX := clipDeltaY * deltaX / deltaY;
end;
tx := X + clipDeltaX + 0.5;
ty := Y + clipDeltaY + 0.5;
end;
// exclude the end-point from the rasterization
if (absDeltaX > 1.0) or (absDeltaY > 1.0) then
begin
CGContextBeginPath(CGContext);
// add 0.5 to both coordinates for better rasterization
CGContextMoveToPoint(CGContext, PenPos.x + 0.5, PenPos.y + 0.5);
CGContextAddLineToPoint(CGContext, X + clipDeltaX + 0.5, Y + clipDeltaY + 0.5);
CGContextStrokePath(CGContext);
end
// But also draw lines with width=1, but note that nothing will be drawn
// for width = 0 (end point = start point)
else
begin
CGContextBeginPath(CGContext);
CGContextMoveToPoint(CGContext, PenPos.x, PenPos.y);
CGContextAddLineToPoint(CGContext, X + clipDeltaX + 0.5, Y + clipDeltaY + 0.5);
CGContextStrokePath(CGContext);
end;
CGContextBeginPath(CGContext);
CGContextMoveToPoint(CGContext, PenPos.x + 0.5, PenPos.y + 0.5);
CGContextAddLineToPoint(CGContext, tx, ty);
CGContextStrokePath(CGContext);
FPenPos.x := X;
FPenPos.y := Y;
end;