About the first option - you can take snapshot of the UI element in its desired size (or bigger that this size) and then insert the image in the PDF using the DrawImage overload that allows you to specify the rendering size. This way the image will be rendered in the PdfViewer with the specified size using the source of the originally bigger image. This combined with the ImageQuality.High option in ImageSource constructor may help to achieve better quality when rendering the UIElement.
With the second option - we have tested this SDK example
with relatively large variety of UIElements and in most cases everything is exported correctly. Basically, the example traverses the WPF visual tree and renders WPF primitives, so it is suitable for exporting different UI scenarios. If you experience any issues with some concrete example you may write to us again so that we can try solving the issue together.
I hope this helps.
the Telerik team
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