Spread 表格控件：打印带背景图的 PDF 文件

Spread 表格控件支持打印到 PDF 文件，通过 PrintInfo 类下的 PrintToPdf 方法可以实现打印 PDF 功能。

最近，有用户询问如何打印带有背景图的PDF文件。虽然，Spread 不内置该功能，但是我们可以同过自定义来实现。

实现方法很简单，设置 Spread 的背景色为透明色，此时Spread的背景图即可见。

详细请参考代码：

  1: private void fpSpread1_PrintBackground(object sender, FarPoint.Win.Spread.PrintBackgroundEventArgs e)

  2:  {

  3:     System.Drawing.Drawing2D.GraphicsState saveState = e.Graphics.Save();

  4:     Rectangle rect = e.SheetRectangle;

  5:     rect.Width = (int)AdjustWorkaroundForPDFPrint((float)rect.Width);

  6:     rect.Height = (int)AdjustWorkaroundForPDFPrint((float)rect.Height);

  7:     e.Graphics.SetClip(rect);

  8:     e.Graphics.SetClip(rect);

  9:     e.Graphics.DrawImage(fpSpread1.BackgroundImage, rect);

 10:     e.Graphics.Restore(saveState);

 11:  }

 12:     private float AdjustWorkaroundForPDFPrint(float value)

 13:  {

 14:     float _ptperInch = 72;

 15:     //Points Per inch

 16:     float pixelPointFactor = (float)(_ptperInch / 96);

 17:     //pixel point factor base on graphic dpi

 18:     float displayPointFactor = (float)(_ptperInch / 100);

 19:     //point factor base on display graphic unit

 20:     return (float)(value * displayPointFactor / pixelPointFactor);

 21:  }