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Handling images in EPiServer programmatically

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The image editor in edit mode uses EPiServer.ImageLibrary to transform images with the great functionality of let another process then the web application to handle it. Senses the handlings of images are heavy both for the CPU and the memory this is a great feature to be able to configure the web site to do this in another process (or another machine). But it is not yet any documentation for it…

I talked to the EPiServer development team that said the API is stable and they agree to publish it – so I hope it will come out in the SDK son, but when we wait for this documentation I can try to describe how it is working.

Assembly:

EPiServer.ImageLibrary

Classes:

EPiServer.ImageLibrary.ImageServiceClient – The image service client to access the service with

Methods:

public ImageServiceClient(

        string endpointConfigurationName)

The constructor of the end point that takes a string defining the endpoints name, the name used by EPiServer are "ImageServiceClientEndPoint" and can be used if you want the same service to handle the web sites images in the same process as the image editor use.

public byte[] RenderImage(

          byte[] imageBuffer,

          IEnumerable<ImageOperation> operations,

          string mimeType,

          float zoomFactor,

          int jpegQuality)

Returns:

A transformed image

Parameters:

imageBuffer – the original image

operations – operations for transforming the image

mimeType – the mime type of the image. Defined mime type are image/png, image/bmp, image/gif, image/tiff, image/jpg, image/jpeg, image/pjpeg

zoomFactor - the zoom factor 1 means 100%

jpegQuality – the Jpeg quality (if mime types is image/jpg, image/jpeg or image/pjpeg) in %

The image operations implemented are given by the enum EPiServer.ImageLibrary.ImageEditorCommand and has the following options:

None - No action

Grayscale - Convert image to grey scale

Crop - Crop image

FlipX - Flip the image on the X axis

FlipY - Flip the image on the Y axis

Resize - Resize the image

Rotate - Rotate the image

Sample code

This web page rotates an image 180 degrees given its virtual path.

Example to flip support Jens up side down (on a EPiServer sample site)

http://localhost/FlipImage.aspx?ImageVirtualPath=/Global/StartPage/cms6_headerEN.jpg

<%@ Page Language="C#" AutoEventWireup="true" Inherits="System.Web.UI.Page" %>
<%@ Import Namespace="EPiServer.ImageLibrary" %>
<%TransformAndViewImage(HttpContext.Current.Request["ImageVirtualPath"]); %>
 
<script runat="server">
    public void TransformAndViewImage(string imageVirtualPath)
    {
        // Operations used to change the image
        ImageOperation[] operations = new ImageOperation[]{
            new ImageOperation(ImageEditorCommand.Rotate) { Angle = 180 }};
        float zoomFactor = 0.5f; //Percent / 100
        string imageMimeType = System.Net.Mime.MediaTypeNames.Image.Jpeg;
        int jpegQuality = 100; //Percent
 
        // ImageServiceClientEndPoint is the same endpoint name that the image editor uses 
        ImageServiceClient imageService = new ImageServiceClient("ImageServiceClientEndPoint");
 
        //// Load the image and apply requested changes
        using (System.IO.Stream fileStream = System.Web.Hosting.HostingEnvironment.VirtualPathProvider.GetFile(imageVirtualPath).Open())
        {
            byte[] orginalImage = new byte[fileStream.Length];
            fileStream.Read(orginalImage, 0, (int)fileStream.Length);
            byte[] imageBuffer = imageService.RenderImage(
                  orginalImage,
                  operations,
                  imageMimeType,
                  zoomFactor,
                  jpegQuality);
 
            Response.ContentType = imageMimeType;
            Response.Cache.SetCacheability(HttpCacheability.ServerAndNoCache);
            Response.OutputStream.Write(imageBuffer, 0, (int)imageBuffer.Length);
            Response.End();
        }
    }
</script>

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About the blogger

Mattias Lövström
EPiServer Stockholm
Citizen

I work at EPiServer Expert services as an EPiServer Expert to help our partners with architecture to avoid that something goes wrong in the implementation phase. And as a troubleshooter if something had gone wrong in the implementation phase.

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