C#/VB.NET Excel 工作表添加水印

本文将介绍如何使用Spire.XLS组件给Excel工作表添加水印。Microsoft Excel没有直接的方法内置水印在Excel工作表中，我们可以通过添加背景图片在视觉上形成独特的水印效果，但是此类背景水印在打印Excel文档时水印图案会丢失。同时，我们也可以通过添加页眉页脚功能，将图片或文字加到Excel文档内容背后，实现类似水印的效果。但是该类水印只在打印预览或将视图模式为“页面视图”下才能直观可见。

通常情况下，水印分为文本水印和图片水印。Spire.XLS添加的水印实际上都为图片水印。下面我们将详细介绍使用Spire.XLS将文本以图片形式添加到Excel中，生成文本水印。

添加背景文本图片水印

static void Main(string[] args)
{
    //加载Excel文档
    Workbook workbook = new Workbook();
    workbook.LoadFromFile("Test.xlsx");

    //设置水印文字和字体
    Font font = new Font("宋体", 36);
    String watermark = "背景水印";

//设置背景图片为水印
    foreach (Worksheet sheet in workbook.Worksheets)
    {
        //调用DrawText()方法创建的图片
        Image imgWtrmrk = DrawText(watermark, font, Color.LightCoral, Color.White, sheet.PageSetup.PageHeight, sheet.PageSetup.PageWidth);
        
        sheet.PageSetup.BackgoundImage = imgWtrmrk as Bitmap;                 
        
}
//保存文档并预览
    workbook.SaveToFile("result.xlsx", ExcelVersion.Version2010);
    System.Diagnostics.Process.Start("result.xlsx");
}
private static Image DrawText(String text, System.Drawing.Font font, Color textColor, Color backColor, double height, double width)
{
    //将用来作为水印的文本返回为图片并设置其展示样式
    Image img = new Bitmap((int)width, (int)height);
    Graphics drawing = Graphics.FromImage(img);
    SizeF textSize = drawing.MeasureString(text, font);
    drawing.TranslateTransform(((int)width - textSize.Width) / 2, ((int)height - textSize.Height) / 2);
    drawing.RotateTransform(-45);
    drawing.TranslateTransform(-((int)width - textSize.Width) / 2, -((int)height - textSize.Height) / 2);
   
    drawing.Clear(backColor);
    Brush textBrush = new SolidBrush(textColor);
    drawing.DrawString(text, font, textBrush, ((int)width - textSize.Width) / 2, ((int)height - textSize.Height) / 2);
    drawing.Save();
    return img;
}

VB.NET

Private Shared Sub Main(args As String())
  '加载Excel文档
  Dim workbook As New Workbook()
  workbook.LoadFromFile("Test.xlsx")

  '设置水印文字和字体
  Dim font As New Font("宋体", 36)
  Dim watermark As [String] = "背景水印"

  '设置背景图片为水印
  For Each sheet As Worksheet In workbook.Worksheets
    '调用DrawText()方法创建的图片
    Dim imgWtrmrk As Image = DrawText(watermark, font, Color.LightCoral, Color.White, sheet.PageSetup.PageHeight, sheet.PageSetup.PageWidth)


    sheet.PageSetup.BackgoundImage = TryCast(imgWtrmrk, Bitmap)
  Next
  '保存文档并预览
  workbook.SaveToFile("result.xlsx", ExcelVersion.Version2010)
  System.Diagnostics.Process.Start("result.xlsx")
End Sub
Private Shared Function DrawText(text As [String], font As System.Drawing.Font, textColor As Color, backColor As Color, height As Double, width As Double) As Image
  '将用来作为水印的文本返回为图片并设置其展示样式
  Dim img As Image = New Bitmap(CInt(width), CInt(height))
  Dim drawing As Graphics = Graphics.FromImage(img)
  Dim textSize As SizeF = drawing.MeasureString(text, font)
  drawing.TranslateTransform((CInt(width) - textSize.Width) / 2, (CInt(height) - textSize.Height) / 2)
  drawing.RotateTransform(-45)
  drawing.TranslateTransform(-(CInt(width) - textSize.Width) / 2, -(CInt(height) - textSize.Height) / 2)

  drawing.Clear(backColor)
  Dim textBrush As Brush = New SolidBrush(textColor)
  drawing.DrawString(text, font, textBrush, (CInt(width) - textSize.Width) / 2, (CInt(height) - textSize.Height) / 2)
  drawing.Save()
  Return img
End Function

C# 给 Excel 工作表添加水印

添加页眉页脚文本图片水印

static void Main(string[] args)
{
    //加载Excel文档
    Workbook workbook = new Workbook();
    workbook.LoadFromFile("Test.xlsx");

    //设置水印文字和字体
    Font font = new Font("宋体", 36);
String watermark = "内部资料";

//在页眉中插入图片作为模拟水印
    foreach (Worksheet sheet in workbook.Worksheets)
    {
        //调用DrawText()方法创建的图片
        Image imgWtrmrk = DrawText(watermark, font, System.Drawing.Color.LightCoral, System.Drawing.Color.White, sheet.PageSetup.PageHeight, sheet.PageSetup.PageWidth);

        //插入图片作为LeftHeaderImage
        sheet.PageSetup.LeftHeaderImage = imgWtrmrk;
        sheet.PageSetup.LeftHeader = "&G";
        
//设置视图模式，页眉水印仅在Layout模式下直观可见
        sheet.ViewMode = ViewMode.Layout;
}
//保存文档并预览
    workbook.SaveToFile("result.xlsx", ExcelVersion.Version2010);
    System.Diagnostics.Process.Start("result.xlsx");
}

private static Image DrawText(String text, System.Drawing.Font font, Color textColor, Color backColor, double height, double width)
{
    //将用来作为水印的文本返回为图片并设置其展示样式
    Image img = new Bitmap((int)width, (int)height);
    Graphics drawing = Graphics.FromImage(img);
    
    SizeF textSize = drawing.MeasureString(text, font);
    drawing.TranslateTransform(((int)width - textSize.Width) / 2, ((int)height - textSize.Height) / 2);
    drawing.RotateTransform(-45);
    drawing.TranslateTransform(-((int)width - textSize.Width) / 2, -((int)height - textSize.Height) / 2);
    drawing.Clear(backColor);
    Brush textBrush = new SolidBrush(textColor);
    drawing.DrawString(text, font, textBrush, ((int)width - textSize.Width) / 2, ((int)height - textSize.Height) / 2);
drawing.Save();
    return img;
}

VB.NET

Private Shared Sub Main(args As String())
  '加载Excel文档
  Dim workbook As New Workbook()
  workbook.LoadFromFile("Test.xlsx")

  '设置水印文字和字体
  Dim font As New Font("宋体", 36)
  Dim watermark As [String] = "内部资料"

  '在页眉中插入图片作为模拟水印
  For Each sheet As Worksheet In workbook.Worksheets
    '调用DrawText()方法创建的图片
    Dim imgWtrmrk As Image = DrawText(watermark, font, System.Drawing.Color.LightCoral, System.Drawing.Color.White, sheet.PageSetup.PageHeight, sheet.PageSetup.PageWidth)

    '插入图片作为LeftHeaderImage
    sheet.PageSetup.LeftHeaderImage = imgWtrmrk
    sheet.PageSetup.LeftHeader = "&G"

    '设置视图模式，页眉水印仅在Layout模式下直观可见
    sheet.ViewMode = ViewMode.Layout
  Next
  '保存文档并预览
  workbook.SaveToFile("result.xlsx", ExcelVersion.Version2010)
  System.Diagnostics.Process.Start("result.xlsx")
End Sub

Private Shared Function DrawText(text As [String], font As System.Drawing.Font, textColor As Color, backColor As Color, height As Double, width As Double) As Image
  '将用来作为水印的文本返回为图片并设置其展示样式
  Dim img As Image = New Bitmap(CInt(width), CInt(height))
  Dim drawing As Graphics = Graphics.FromImage(img)

  Dim textSize As SizeF = drawing.MeasureString(text, font)
  drawing.TranslateTransform((CInt(width) - textSize.Width) / 2, (CInt(height) - textSize.Height) / 2)
  drawing.RotateTransform(-45)
  drawing.TranslateTransform(-(CInt(width) - textSize.Width) / 2, -(CInt(height) - textSize.Height) / 2)
  drawing.Clear(backColor)
  Dim textBrush As Brush = New SolidBrush(textColor)
  drawing.DrawString(text, font, textBrush, (CInt(width) - textSize.Width) / 2, (CInt(height) - textSize.Height) / 2)
  drawing.Save()
  Return img
End Function

C# 给 Excel 工作表添加水印

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C#/VB.NET Excel 工作表添加水印

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