(lazarus)把chart画到canvas里面

    http://wiki.lazarus.freepascal.org/BGRABitmap_tutorial_TAChart

    原文的代码已经与最新的pkg不相匹配，更改后如下：

uses TABGRAUtils, TADrawUtils, TADrawerCanvas, BGRABitmap, TADrawerBGRA; 

....

procedure TForm1.PaintBox1Paint(Sender: TObject);
var
  bmp: TBGRABitmap;
  id: IChartDrawer;
  rp: TChartRenderingParams;
begin
  bmp := TBGRABitmap.Create(PaintBox1.Width, PaintBox1.Height);
  Chart1.DisableRedrawing;
  try
    id := TBGRABitmapDrawer.Create(bmp);
    id.DoGetFontOrientation := @CanvasGetFontOrientationFunc;
    rp := Chart1.RenderingParams;
    Chart1.Draw(id, Rect(0, 0, PaintBox1.Width, PaintBox1.Height));
    Chart1.RenderingParams := rp;
    bmp.Draw(PaintBox1.Canvas, 0, 0);
  finally
    Chart1.EnableRedrawing;
    bmp.Free;
  end;


end;   

    为防止图像闪烁，可以使用BGRAControls中的TBGRAVirtualScreen控件。