[lazarus] Canvas, Arc/Chord/Pie etc. & Polybezier

[Mattias Gaertner]

Great :)

Plz send whatever you want to submit to me. I will add it.

Mattias



On Tue, 06 Aug 2002 12:39:40 -0400
"Andrew Johnson" <aj_genius at hotmail.com> wrote:

> I really don't know where to send stuff like this, but I have a file of 
> Graphics/Math routines I started initially for Delphi/Kylix Canvas 
> intercompatibility but that later got added to and modified for use with 
> Freepascal and GTK etc. While there are a few bugs(and at the moment is 
> somewhat disorganized), it includes ArcRadialAngles2Points, and reverse for 
> Arc/Chord/Pie routines to enable overloaded canvas routines for each, one 
> with Angle Params: as in Lazarus/Kylix, and one for Radial Points: like in 
> Delphi. A quick hacked example of how to add RadialPoint support to the 
> GTKObject would be :
> 
> Uses gdmhroutines;
> ....
> function TgtkObject.Arc(DC: HDC; x,y,width,height : Integer;
>   StartPoint, EndPoint : TPoint): Boolean;
> var
>   Angle1, Angle2 : Extended;
> begin
>   ArcRadialCoords2Angles(X,Y,X+Width,Y+Height,StartPoint.X,
>     StartPoint.Y,EndPoint.X,EndPoint.Y,Angle1,Angle2);
> 
>   {Angle results are in 1/64's of a degree for compatibility w/X}
> 
>   Result := Arc(DC,x,y,width,height,Trunc(Angle1 / 4),
>     Trunc(Angle2 / 4));
> end;
> 
> There are inconsistencies I haven't worked out in the conversion routines 
> which cause results to be off in one direction or another by exactly 1 
> degree, though this may actually be a discrepency between Windows and GTK 
> Arcs. I also have initial support for PolyBezier2Polyline since GDK doesn't 
> directly support Beziers which could be used to add a PolyBezier routine. 
> While I can't guarentee a lot on account of my schedule, I know a fair bit 
> about GDK vs WinAPI drawing routines and am willing to submit stuff I 
> already have written, modified for Lazarus. I feel this is one area that 
> Lazarus has always been weak in, and since I couldn't really help out much 
> anywhere else I'd be willing to give a shot at filling in at least some of 
> the gaps.
> 
> TTFN
> Andrew
> 
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