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

[Andrew Johnson]

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

_________________________________________________________________
Chat with friends online, try MSN Messenger: http://messenger.msn.com