Add watermark to JPEG images
In this tutorial, you implement a file processor, called WatermarkMaker, that is executed each time you upload a JPEG image in your library. The file processor adds a watermark in the top left corner of every image you upload.
Original image:
Processed image:
You first create the file processor class and then add the file processor in the administration settings in Sitefinity CMS backend.
Implement the file processor
Create a file processor class that inherits the FileProcessorBase class. Next, implement your logic for the CanProcessFile and Process methods:
using System.Collections.Specialized;
using System.Drawing;
using System.Drawing.Imaging;
using System.IO;
using Telerik.Sitefinity.FileProcessors;
using Telerik.Sitefinity.Processors;
namespace MyFileProcessors
{
public class WatermarkMaker : ProcessorBase, IFileProcessor
{
private string font;
private string text;
private string color;
protected override void Initialize(NameValueCollection config)
{
this.font = config["Font"] ?? "Arial";
this.color = config["Color"] ?? "Black";
this.text = config["Text"] ?? "Example txt";
}
public bool CanProcessFile(FileProcessorInput fileInput)
{
if (fileInput.MimeType == "image/jpeg")
{
return true;
}
return false;
}
public Stream Process(FileProcessorInput fileInput)
{
Stream output = new MemoryStream();
// load the image
Image img = Image.FromStream(fileInput.FileStream);
// set font
Font font = new Font(this.font, 20, FontStyle.Bold, GraphicsUnit.Pixel);
// set color
Color color = Color.FromName(this.color);
Point pt = new Point(5, 5);
SolidBrush brush = new SolidBrush(color);
// draw watermark text
Graphics graphics = Graphics.FromImage(img);
graphics.DrawString(this.text, font, brush, pt);
graphics.Dispose();
// save the image into a stream
img.Save(output, ImageFormat.Jpeg);
img.Dispose();
output.Position = 0;
return output;
}
}
}NOTE: In the code above, you also override the
Initialize(NameValueCollection config)method. The config parameter, passed to the method, lists all additional parameters that the file processor uses. In this example,font,color, andtext.
Add the file processor as administration setting
- In Sitefinity CMS backend, navigate to Administration » Settings » Advanced settings.
- Expand the Libraries node and click File processors.
Click Create new. - Enter the following:
-
Name:
WatermarkMaker -
Description:
Watermark maker for JPEG images -
Type:
MyFileProcessors.WatermarkMakerNOTE:The type must be identical to the name of the class you implemented in the previous section of the tutorial.
- Save your changes.
- To add parameters to the WatermarkMaker processor, expand its node and for each of the parameters, enter the following values, and save your changes:
Parameter
Value
Text
ExampleFont
ArialColor
RedAs a result, all images of MIME type “
image/jpeg”, for example, JPEG, JPG, and JPE are processed by the WatermarkMaker file processor before being saved in the library.
