Loading of external resources containing by a document Leave feedback
If the document contains external resources, such as images, GroupDocs.Viewer loads them when rendering a document. This allows the document to display correctly, but is a potential security risk.
GroupDocs.Viewer allows you to manage loading of external resources contained by a document. These features are supported for the following formats:
Use the LoadOptions object to manage loading of external resources.
The following code snippet shows how to deny loading of external resources:
using GroupDocs.Viewer;
using GroupDocs.Viewer.Options;
// ...
LoadOptions loadOptions = new LoadOptions();
loadOptions.SkipExternalResources = true; // Skip loading of external resources
using (Viewer viewer = new Viewer("business-flyer.docx", loadOptions))
{
HtmlViewOptions viewOptions =
HtmlViewOptions.ForEmbeddedResources();
viewer.View(viewOptions);
}
Imports GroupDocs.Viewer
Imports GroupDocs.Viewer.Options
' ...
Module Program
Sub Main(args As String())
Dim loadOptions As LoadOptions = New LoadOptions()
loadOptions.SkipExternalResources = True ' Skip loading of external resources
Using viewer As Viewer = New Viewer("business-flyer.docx", loadOptions)
Dim viewOptions As HtmlViewOptions = HtmlViewOptions.ForEmbeddedResources()
viewer.View(viewOptions)
End Using
End Sub
End Module
The following images show the output file with and without external resources (see top right corner):
| loadOptions.SkipExternalResources = false | loadOptions.SkipExternalResources = true |
|---|---|
 |  |
The following code snippet shows how to allow loading of external resources from specific URLs:
using GroupDocs.Viewer;
using GroupDocs.Viewer.Options;
// ...
LoadOptions loadOptions = new LoadOptions();
loadOptions.SkipExternalResources = true; // Skip loading of all external resources
loadOptions.WhitelistedResources.Add("avatars.githubusercontent.com"); //Enable loading of external resources that has `avatars.githubusercontent.com` fragment in resource URL.
using (Viewer viewer = new Viewer("business-flyer.docx", loadOptions))
{
HtmlViewOptions viewOptions =
HtmlViewOptions.ForEmbeddedResources();
viewer.View(viewOptions);
}
Imports GroupDocs.Viewer
Imports GroupDocs.Viewer.Options
' ...
Module Program
Sub Main(args As String())
Dim loadOptions As LoadOptions = New LoadOptions()
loadOptions.SkipExternalResources = True ' Skip loading of all external resources
loadOptions.WhitelistedResources.Add("avatars.githubusercontent.com") 'Enable loading of external resources that has `avatars.githubusercontent.com` fragment in resource URL.
Using viewer As Viewer = New Viewer("business-flyer.docx", loadOptions)
Dim viewOptions As HtmlViewOptions = HtmlViewOptions.ForEmbeddedResources()
viewer.View(viewOptions)
End Using
End Sub
End Module
The default timeout is 30 seconds. GroupDocs.Viewer allows you to change this value.
The following code snippet shows how to set a timeout to load external resources:
using System;
using GroupDocs.Viewer;
using GroupDocs.Viewer.Options;
// ...
// Specify a timeout.
LoadOptions loadOptions = new LoadOptions();
loadOptions.ResourceLoadingTimeout = TimeSpan.FromSeconds(5);
// Render a file.
using (Viewer viewer = new Viewer("sample.docx", loadOptions))
{
HtmlViewOptions viewOptions = HtmlViewOptions.ForEmbeddedResources();
viewer.View(viewOptions);
}
Imports System
Imports GroupDocs.Viewer
Imports GroupDocs.Viewer.Options
' ...
Module Program
Sub Main(args As String())
' Specify a timeout.
Dim loadOptions As LoadOptions = New LoadOptions()
loadOptions.ResourceLoadingTimeout = TimeSpan.FromSeconds(5)
' Render a file.
Using viewer As Viewer = New Viewer("sample.docx", loadOptions)
Dim viewOptions As HtmlViewOptions = HtmlViewOptions.ForEmbeddedResources()
viewer.View(viewOptions)
End Using
End Sub
End Module
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