Thumbnails

Aug 23, 2024
2 minutes to read

Image Thumbnails

ASPxFileManager automatically creates thumbnails for image files with the following file extensions:

bmp
gif
ico
jpg
jpeg
png

For better performance, these content-based thumbnails are stored in the location specified by the FileManagerSettings.ThumbnailFolder property.

Note

The folder that contains thumbnails must be placed inside the application folder.

Default Thumbnails

ASPxFileManager includes default thumbnails for the file types listed below.

File Extension

Default Thumbnail

| | --- | --- | |

txt

| |

rtf

doc

docx

odt

| |

xls

xlsx

ods

| |

ppt

pptx

odp

| |

pdf

| |

Other extensions, where thumbnails are not defined

Use the FileManagerImages.File property to change the thumbnail for a file.

Custom Thumbnails

In addition to automatically created and default thumbnails, ASPxFileManager allows you to make custom thumbnails available to users by handling the ASPxFileManager.CustomThumbnail server event. This event allows you to define whether all files or certain files should be displayed in folders. Within the event handler, use the FileManagerThumbnailCreateEventArgs.Item property to access and identify the currently processed item. To define a custom thumbnail for the file, use the FileManagerThumbnailCreateEventArgs.ThumbnailImage property.

In the example below, the CustomThumbnail event is handled to analyze file extensions and represent each file type using the corresponding custom thumbnail image.

C#
ASPX

csharp

public void ASPxFileManager1_CustomThumbnail(object source, DevExpress.Web.FileManagerThumbnailCreateEventArgs e) {
        switch(((FileManagerFile)e.Item).Extension) {
            case ".avi":
                e.ThumbnailImage.Url = "Images/movie.png";
                break;
            case ".zip":
                e.ThumbnailImage.Url = "Images/archive.png";
                break;
            case ".txt":
                e.ThumbnailImage.Url = "Images/txt.png";
                break;
            case ".rtf":
                e.ThumbnailImage.Url = "Images/richtxt.png";
                break;
            case ".mp3":
                e.ThumbnailImage.Url = "Images/music.png";
                break;
            case ".xml":
                e.ThumbnailImage.Url = "Images/code.png";
                break;
        }
}

aspx

<dx:ASPxFileManager ID="ASPxFileManager1" runat="server" OnCustomThumbnail="ASPxFileManager1_CustomThumbnail">
        <Settings RootFolder="~/Content/FileManager/Files" ThumbnailFolder="~/Content/FileManager/Thumbnails"
            AllowedFileExtensions=".jpg,.rtf,.txt,.avi,.png,.mp3,.xml" InitialFolder="Documents" />
        <SettingsUpload Enabled="false"></SettingsUpload>
</dx:ASPxFileManager>