Rotacionar Imagem

procedure TImg.RotateBMP(Angle: Real);
var
  ang,cos_angle,sin_angle: Double;
  newWidth,newHeight,nWidth,nHeight,
  x,y,newX,newY,oldX,oldY: Integer;
  p1,p2,p3,p4,newP1,newP2,newP3,newP4, leftTop, rightTop, leftBottom, rightBottom: TPoint;
  NovoBmp: TBitmap;
begin
  ang := -(angle* Pi)/180;
nWidth := m_nWidth;
nHeight := m_nHeight;
cos_angle := cos(ang);
sin_angle := sin(ang);

// Calculate the size of the new bitmap
p1 := Point(0,0);
p2 := Point(nWidth,0);
p3 := Point(0,nHeight);
p4 := Point(nWidth-1,nHeight);

newP1.x := p1.x;
newP1.y := p1.y;
newP2.x := round(p2.x*cos_angle - p2.y*sin_angle);
newP2.y := round(p2.x*sin_angle + p2.y*cos_angle);
newP3.x := round(p3.x*cos_angle - p3.y*sin_angle);
newP3.y := round(p3.x*sin_angle + p3.y*cos_angle);
newP4.x := round(p4.x*cos_angle - p4.y*sin_angle);
newP4.y := round(p4.x*sin_angle + p4.y*cos_angle);

leftTop.x := min(min(newP1.x,newP2.x),min(newP3.x,newP4.x));
leftTop.y := min(min(newP1.y,newP2.y),min(newP3.y,newP4.y));
rightBottom.x := max(max(newP1.x,newP2.x),max(newP3.x,newP4.x));
rightBottom.y := max(max(newP1.y,newP2.y),max(newP3.y,newP4.y));
leftBottom.x := leftTop.x;
leftBottom.y := 2+rightBottom.y;
rightTop.x := 2+rightBottom.x;
rightTop.y := leftTop.y;

newWidth := rightTop.x - leftTop.x;
newHeight := leftBottom.y - leftTop.y;

  //NovoBmp
  NovoBmp := TBitmap.Create;
  NovoBmp.Width := newWidth;
  NovoBmp.Height := newHeight;
  NovoBmp.Canvas.FillRect(Rect(0,0,NewWidth,NewHeight));
//imgDest.Create(newWidth,newHeight,GetBpp(),GetType());
//imgDest.SetPalette(GetPalette());

  newY := 0;
for y := leftTop.y to leftBottom.y do
    begin
      //info.nProgress = (long)(100*newY/newHeight);
//if (info.nEscape) break;
      newX := 0;
for x := leftTop.x to rightTop.x do
        begin
oldX := round(x*cos_angle + y*sin_angle - 0.5);
oldY := round(y*cos_angle - x*sin_angle - 0.5);
        if ( oldX >= 0 ) and ( oldX < m_nWidth ) and ( oldY >= 0 ) and ( oldY < m_nHeight ) then
          NovoBmp.Canvas.Pixels[newX,newY] := Canvas.Pixels[oldX,oldY]
        else
          NovoBmp.Canvas.Pixels[newX,newY] := clWhite;
        inc(newX);
        end;
      inc(newY);
    end;
//select the destination
Picture.Bitmap := NovoBmp;
  m_nWidth := newWidth;
  m_nHeight := newHeight;
  Width := newWidth;
  Height := newHeight;

  NovoBmp.Free;
end;