为何画出的线不是平滑的？

Question

procedure TForm1.Button2Click(Sender: TObject); 
begin 
        self.Canvas.pen.Style:=pssolid; 
        self.Canvas.pen.Width:=1;       self.Canvas.PolyBezier([Point(10, 210), Point(30, 10), 
                              Point(130, 130), Point（240,120),Point(340, 220),Point(440, 620),Point(10, 210)]); 
end;

Answer 1

PolyBezier函数好象只能做三个控制点的贝赛尔曲线..下载一下这个例子看看吧..这才是真正的贝赛尔曲线的算法..
[老外写的Delphi的贝赛尔曲线的算法..我感觉不大好..但总好过没有吧..-_-!..你适当改改吧]
http://www.triplexware.huckfinn.de/src/geom_api/bezier.zip

Answer 2

反走样线的画线函数:
procedure AALine(x1,y1,x2,y2 : single; color : tcolor; canvas : tcanvas);
function CrossFadeColor(FromColor,ToColor : TColor; Rate : Single) : TColor; 
var r,g,b : byte; 
begin 
  r:=Round(GetRValue(FromColor)*Rate+GetRValue(ToColor)*(1-Rate)); 
  g:=Round(GetGValue(FromColor)*Rate+GetGValue(ToColor)*(1-Rate)); 
  b:=Round(GetBValue(FromColor)*Rate+GetBValue(ToColor)*(1-Rate));
  Result:=RGB(r,g,b); 
end; 
procedure hpixel(x : single; y : integer); 
var FadeRate : single; 
begin 
  FadeRate:=x-trunc(x); 
  with canvas do 
  begin 
    pixels[trunc(x),y]:=CrossFadeColor(Color,Pixels[Trunc(x),y],1-FadeRate); 
    pixels[trunc(x)+1,y]:=CrossFadeColor(Color,Pixels[Trunc(x)+1,y],FadeRate); 
  end; 
end; procedure vpixel(x : integer; y : single); 
var FadeRate : single;
begin 
  FadeRate:=y-trunc(y); 
  with canvas do 
  begin 
    pixels[x,trunc(y)]:=CrossFadeColor(Color,Pixels[x,Trunc(y)],1-FadeRate); 
    pixels[x,trunc(y)+1]:=CrossFadeColor(Color,Pixels[x,Trunc(y)+1],FadeRate); 
  end; 
end; var i : integer; 
    ly,lx,currentx,currenty,deltax,deltay,l,skipl : single; 
begin
  if (x1<>x2) or (y1<>y2) then
  begin 
    currentx:=x1; 
    currenty:=y1; 
    lx:=abs(x2-x1); 
    ly:=abs(y2-y1);     if lx>ly then
    begin 
      l:=trunc(lx); 
      deltay:=(y2-y1)/l; 
      if x1>x2 then
      begin
        deltax:=-1; 
        skipl:=(currentx-trunc(currentx));
      end else 
      begin 
        deltax:=1; 
        skipl:=1-(currentx-trunc(currentx)); 
      end; 
    end else
    begin 
      l:=trunc(ly); 
      deltax:=(x2-x1)/l; 
      if y1>y2 then
      begin 
        deltay:=-1; 
        skipl:=(currenty-trunc(currenty)); 
      end else 
      begin 
        deltay:=1; 
        skipl:=1-(currenty-trunc(currenty)); 
      end;
    end;    currentx:=currentx+deltax*skipl;
    currenty:=currenty+deltay*skipl;{}    for i:=1 to trunc(l) do
    begin
      if lx>ly then vpixel(trunc(currentx),currenty) else hpixel(currentx,trunc(currenty));
      currentx:=currentx+deltax;
      currenty:=currenty+deltay;
    end;
  end;
end;