Merge pull request #431 from telerik/new-kb-add-watermark-pdf-radpdfprocessing-148c1282b51b44c38dd649ca2925a3e3

Added new kb article add-watermark-pdf-radpdfprocessing

Author: dessyordanova

knowledge-base/add-watermark-pdf-radpdfprocessing.md

@@ -0,0 +1,81 @@
+---
+title: Adding a Watermark to PDF Files Using RadPdfProcessing
+description: Learn how to add custom watermarks to PDF documents using the RadPdfProcessing library.
+type: how-to
+page_title: How to Add Watermarks to PDF Documents with RadPdfProcessing
+slug: add-watermark-pdf-radpdfprocessing
+tags: radpdfprocessing, document processing, watermark, pdf, text watermark
+res_type: kb
+ticketid: 1653970
+---
+
+## Environment
+
+| Version | Product | Author | 
+| --- | --- | ---- | 
+| 2024.2.426| RadPdfProcessing |[Desislava Yordanova](https://www.telerik.com/blogs/author/desislava-yordanova)| 
+
+## Description
+
+This KB article demonstrates how to add a text watermark across all pages of a PDF document using RadPdfProcessing.
+
+## Solution
+
+To add a watermark to PDF pages using RadPdfProcessing, follow these steps:
+
+1. Import the PDF document using [PdfFormatProvider]({%slug radpdfprocessing-formats-and-conversion-pdf-pdfformatprovider%}).
+2. Iterate through each page of the document.
+3. Use [FixedContentEditor]({%slug radpdfprocessing-editing-fixedcontenteditor%}) to add a watermark text block to each page.
+4. Customize the watermark's text properties, color, and position.
+5. [Export](https://docs.telerik.com/devtools/document-processing/libraries/radpdfprocessing/formats-and-conversion/pdf/pdfformatprovider/pdfformatprovider#export) the document with watermarks back to a PDF file.
+
+Here is a complete code snippet demonstrating these steps:
+
+```csharp
+        static void Main(string[] args)
+        {
+            string fileName = "sample.pdf";
+            PdfFormatProvider provider = new PdfFormatProvider();
+            RadFixedDocument document = provider.Import(File.ReadAllBytes(fileName));
+
+            foreach (RadFixedPage page in document.Pages)
+            {
+                AddWatermarkText(page, "Watermark text!", 100);
+            }
+
+            string exportFileName = "testWatermarks.pdf";
+            File.Delete(exportFileName);
+
+            File.WriteAllBytes(exportFileName, new PdfFormatProvider().Export(document));
+            ProcessStartInfo psi = new ProcessStartInfo()
+            {
+                FileName = exportFileName,
+                UseShellExecute = true
+            };
+            Process.Start(psi);
+        }
+
+        private static void AddWatermarkText(RadFixedPage page, string text, byte transparency)
+        {
+            FixedContentEditor editor = new FixedContentEditor(page);
+
+            Block block = new Block();
+            block.TextProperties.FontSize = 80;
+            block.TextProperties.TrySetFont(new FontFamily("Arial"), FontStyles.Normal, FontWeights.Bold);
+            block.HorizontalAlignment = Telerik.Windows.Documents.Fixed.Model.Editing.Flow.HorizontalAlignment.Center;
+            block.GraphicProperties.FillColor = new RgbColor(transparency, 255, 0, 0);
+            block.InsertText(text);
+
+            double angle = -45;
+            editor.Position.Rotate(angle);
+            editor.Position.Translate(0, page.Size.Width);
+            editor.DrawBlock(block, new Size(page.Size.Width / Math.Abs(Math.Sin(angle)), double.MaxValue));
+        }
+```
+
+![Pdf Watermark](images/pdf-watermark.png)  
+
+## See Also
+
+- [FixedContentEditor]({%slug radpdfprocessing-editing-fixedcontenteditor%}) 
+- [SDK Example: Add Watermark](https://github.com/telerik/document-processing-sdk/blob/master/PdfProcessing/AddWatermark/Program.cs)

knowledge-base/images/pdf-watermark.png

@@ -300,6 +300,7 @@ __FixedContentEditor__ has some properties and methods that affect how it will b
  * [Clipping]({%slug radpdfprocessing-concepts-clipping%})
  * [Table]({%slug radpdfprocessing-editing-table%})
  * [How to Generate a PDF Document from Images with FixedContentEditor]({%slug pdf-from-images-with-fixedcontenteditor%})
+ * [Adding a Watermark to PDF Files Using RadPdfProcessing]({%slug add-watermark-pdf-radpdfprocessing%})
  * [Adding Images with a Shadow in PDF Documents]({%slug add-shadow-image-radpdfprocessing%})
  * [Splitting a Large Image Across Multiple PDF Pages]({%slug split-export-large-image-multiple-pdf-pages-radpdfprocessing%})
  * [Resizing Large Images to Fit in the PDF Page]({%slug resize-images-radpdfprocessing%})