Document Presenter
The document presenter handles the display of the document pages and the internal document navigation. It also controls the selection markers, the conversion between view and document location coordinates, and the proper response to mouse and touch events.
Out of the box, the PdfViewer provides the FixedDocumentPagesPresenter and FixedDocumentSinglePageViewPresenter presenters.
By default, the PdfViewer uses the FixedDocumentPagesPresenter, which displays the pages in a vertical order with a fixed margin between them. Each page is centered horizontally inside the control's viewport.
The FixedDocumentSinglePageViewPresenter displays a single page inside the viewport. The page is vertically and horizontally centered.
To change the current document presenter, set the FixedDocumentPresenter property of RadPdfViewer.
Change the document presenter
this.radPdfViewer.FixedDocumentPresenter = this.radPdfViewer.GetRegisteredPresenter(FixedDocumentPresenterNames.FixedDocumentSinglePageViewPresenter);
VisiblePagesCacheOffset property, which you can use to control the amount of pages that are cached before and after the visible ones. The default value of property is 1.