这段代码 我怎么编绎不过去,请高手帮忙 谢谢

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下面这段代码 我怎么编绎不过去,请高手帮忙 谢谢  left1.x=76   left1.y=348，   left2.x=465  left2.y=716
right1.x=470 right1.y=348,   right2.x=860 right1.y=716 是图上的四个点坐标procedure TmainForm.Start();
var
CurDC: HDC;
FullscreenCanvas:TCanvas;
i,j:Integer;
lx,ly,rx,ry:Integer;
lc,rc:TColor;
clr,clr2:Tcolor;
begin
if (bAuto=True) And (Not GetPos()) then
exit;
clr:=RGB(0,0,255);
clr2:=RGB(255,0,0);
CurDC := GetDC(0); //DC
FullscreenCanvas := TCanvas.Create;
FullscreenCanvas.Handle := CurDC;
FullscreenCanvas.Pen.Color:=clr;
FullscreenCanvas.Pen.Width:=1;
i:=left1.X;
j:=left1.Y;
while(i<=left2.X) do
begin
//
while(j<left2.Y) do
begin
//
lx:=i;ly:=j;
rx:=right1.X-left1.X+lx; ry:=ly;
lc:=GetColor(lx,ly);
rc:=GetColor(rx,ry);
if lc<>rc then
begin
//绘制点
FullscreenCanvas.Pixels[lx,ly]:=clr;
FullscreenCanvas.Pixels[lx+1,ly+1]:=clr2;
FullscreenCanvas.Pixels[lx-1,ly-1]:=clr;
FullscreenCanvas.Pixels[lx+1,ly-1]:=clr2;
FullscreenCanvas.Pixels[lx-1,ly+1]:=clr;
end;
//
j:=j+step;
end;
//
j:=left1.Y;
i:=i+step;
end;
FullscreenCanvas.Free;
ReleaseDC (0, CurDC);
end;