C # Add a watermark instance to Excel

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 there are other workarounds that can be used to solve this problem, 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. Before I also shared how to add watermarks to Word documents and PDF files to add a watermark method, there is a need to also reference.

Here I have downloaded a free version of the Excel component, E-iceblue company developed, 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 namespace:

Using system;using system.drawing;using system.windows.forms;using Spire.xls;

This is the original Excel table:

Here are the 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 images 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 the background drawing. Clear (BackColor); Create text brushes 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 added 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 a layout, be sure to remember to change the view mode to layout.

Font font = new System.Drawing.Font ("Arial", 40); String watermark = "internal data"; foreach (Worksheet sheet in workbook. Worksheets) {//Call DrawText () method to create a new picture System.Drawing.Image IMGWTRMRK = DrawText (watermark, Font, System.Drawing.Color.LightCoral, System.Drawing.Color.White, sheet. Pagesetup.pageheight, Sheet. Pagesetup.pagewidth); Sets the header picture to left-justified sheet. Pagesetup.leftheaderimage = IMGWTRMRK; Sheet. Pagesetup.leftheader = "&g"; The watermark will 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");

：

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 () {InitializeComponent (); private void Button1_Click (object sender, EventArgs e) {//Initializes a new workbook and loads the file to be added to the watermark Workbook Workbook      = new Workbook (); Workbook.      LoadFromFile (@ "C:\Users\Administrator\Desktop\sample.xlsx");      Insert Picture in header font font = new System.Drawing.Font ("Arial", 40);      String watermark = "internal data"; foreach (Worksheet sheet in workbook. Worksheets) {//Call DrawText () method to create a new picture System.Drawing.Image IMGWTRMRK = DrawText (watermark, Font, SYSTEM.DR Awing. Color.lightcoral, System.Drawing.Color.White, sheet. Pagesetup.pageheight, Sheet.        Pagesetup.pagewidth); Sets the header picture to left-justified sheet.        Pagesetup.leftheaderimage = IMGWTRMRK; Sheet.        Pagesetup.leftheader = "&g"; The watermark will 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, Co Lor BackColor, double height, double width) {//Create a bitmap image of the specified width and height images img = new Bitmap ((int) width, (int) Heig      HT);      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 the background drawing.      Clear (BackColor);      Create text brushes 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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