C # Add a watermark instance to Excel _c# tutorial

How to add a watermark to excel in C #

We know that Microsoft Excel does not have built-in functionality to add watermarks directly to Excel tables, but we can actually work around this problem in other ways, such as by adding a header picture or WordArt to mimic the appearance of the watermark. So in this article, I'll show you how to add a watermark to Excel by creating and inserting a header picture in Excel. I also shared how to add a watermark to a Word document and add a watermark to a PDF file, as well as the need for reference.

Here I downloaded a free version of the Excel component, E-iceblue, which was developed by the company, which saves time and simplifies the code.

After the control is installed, create the project, add the DLL file under the installation directory as a reference to the project, and add the following namespaces:

Using System;
Using System.Drawing;
Using System.Windows.Forms;
Using Spire.xls;

This is a screenshot of the original Excel table:

The following are detailed steps and code snippets:

Step 1: First define a DrawText () method, and create a picture based on the contents of the string. The string can be "confidential", "Draft", "Sample", or any text you want to display as a watermark.

private static System.Drawing.Image DrawText (String text, System.Drawing.Font Font, color textcolor, color BackColor, Dou ble height, double width) <br>{
 //Create a bitmap image of the specified width and height the image
 img = new Bitmap (int) width, (int) height);
 Graphics drawing = Graphics.fromimage (IMG);
 Gets the text size
 SizeF textsize = drawing. MeasureString (text, font);
 Rotate the picture
 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);
 Draws a background
 drawing. Clear (BackColor);
 Create a text brush
 Brush textbrush = new SolidBrush (textcolor);
 Drawing. DrawString (text, font, Textbrush, ((int) width-textsize.width)/2, ((int) height-textsize.height)/2);
 Drawing. Save ();
 return img;
}

Step 2: Initialize a new workbook and load the file that adds the watermark.

Workbook workbook = new Workbook ();
Workbook. LoadFromFile (@ "C:\Users\Administrator\Desktop\sample.xlsx");

Step 3: Call the DrawText () method to create a new picture and set the header picture to left-aligned. Second, because the header picture is displayed when the view mode is layout, make sure you remember to change the view mode to layout.

Font font = new System.Drawing.Font ("Arial");
String watermark = "internal data";
foreach (worksheet sheet in workbook. Worksheets)
{
 //Call DrawText () method new picture
 System.Drawing.Image imgwtrmrk = DrawText (watermark, Font, System.Drawing.Color.LightCoral, System.Drawing.Color.White, sheet. Pagesetup.pageheight, Sheet. Pagesetup.pagewidth);
 Set the header picture to left-aligned
 sheet. Pagesetup.leftheaderimage = IMGWTRMRK;
 Sheet. Pagesetup.leftheader = "&g";
 Watermarks only show sheet in this mode
 . ViewMode = viewmode.layout;
 }

Step 4: Save and open the file.

Workbook. SaveToFile ("watermark. xlsx", excelversion.version2010);
System.Diagnostics.Process.Start ("watermark. xlsx");

Effect Chart:

All code:

Using System;
Using System.Drawing;
Using System.Windows.Forms;
 
Using Spire.xls; namespace Add_watermark_to_excel {public partial class Form1:form {public Form1 () {Initializecompon
    ENT (); } private void Button1_Click (object sender, EventArgs e) {//Initialize a new workbook and load the file to add the Watermark workbook workbook
      = new Workbook (); Workbook.
      LoadFromFile (@ "C:\Users\Administrator\Desktop\sample.xlsx");
      Inserts a picture in the header font font = new System.Drawing.Font ("Arial", 40);
      String watermark = "internal data"; foreach (worksheet sheet in workbook. Worksheets) {//Call DrawText () method new picture System.Drawing.Image IMGWTRMRK = DrawText (watermark, Font, System . Drawing.Color.LightCoral, System.Drawing.Color.White, sheet. Pagesetup.pageheight, Sheet.
        Pagesetup.pagewidth); Set the header picture to left-aligned sheet.
        Pagesetup.leftheaderimage = IMGWTRMRK; Sheet.
        Pagesetup.leftheader = "&g"; Watermarks only show sheet in this mode. ViewMode = Viewmode.layout;
      } workbook.
      SaveToFile ("watermark. xlsx", excelversion.version2010);
    System.Diagnostics.Process.Start ("watermark. xlsx"); } <br> private static System.Drawing.Image DrawText (String text, System.Drawing.Font Font, Color TextColor, C Olor BackColor, double height, double width {//Create a bitmap image with a specified width and height the image img = new Bitmap (int) width, (int)
      height);
      Graphics drawing = Graphics.fromimage (IMG); Gets the text size SizeF textsize = drawing.
      MeasureString (text, font); Rotate the picture 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); Draws a background drawing.
      Clear (BackColor);
      Create a text brush Brush Textbrush = new SolidBrush (textcolor); Drawing.
  DrawString (text, font, Textbrush, ((int) width-textsize.width)/2, ((int) height-textsize.height)/2);    Drawing.
      Save ();
    return img;
 }
 
  } 
}

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