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procedure TForm1.PaintBox1Paint(Sender: TObject; Canvas: TCanvas);var bitmap :TBitMap;    pt1, pt2 :TPointF;begin  pt1 := TPointF.Create(0, 0);  pt2 := TPointF.Create(PaintBox1.Width, PaintBox1.Width);  //ShowMessage('yes');  bitmap := TBitMap.Create(Trunc(PaintBox1.Width), Trunc(PaintBox1.Width));  try    bitmap.Canvas.BeginScene(); // ZC: 做画图工作时，这一句必须要    bitmap.Canvas.Stroke.Kind := TBrushKind.bkSolid;    bitmap.Canvas.Stroke.Color := TAlphaColorRec.Black;    bitmap.Canvas.DrawLine(pt1, pt2, 1);    bitmap.Canvas.EndScene;     // ZC: 做画图工作时，这一句必须要    //TCanvas.CopyBitmap(bitmap, Canvas.Bitmap);    //PaintBox1.Canvas.BeginScene(); // ZC: 这里，可以不执行这一句    PaintBox1.Canvas.DrawBitmap(      bitmap,      TRectF.Create(0, 0, PaintBox1.Width, PaintBox1.Width),      TRectF.Create(0, 0, PaintBox1.Width, PaintBox1.Width),      1);    //PaintBox1.Canvas.EndScene;     // ZC: 这里，可以不执行这一句  finally    if Assigned(bitmap) then      bitmap.Free;  end;end;

 

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