PDFViewCtrl's page view mode controls the default zoom level of pages and documents. New documents will automatically open at the zoom level specified by the mode.

PDFViewCtrl supports the following page view modes:

Page view mode (Xamarin.Android / Xamarin.iOS)	Description	Screenshot-portrait	Screenshot-landscape
PDFViewCtrl.PageViewModes.FitPage / pdftron.PDF.PageViewModes.e_fit_page	The zoom is set so that the entire page is visible without scrolling.
PDFViewCtrl.PageViewModes.FitWidth / pdftron.PDF.PageViewModes.e_fit_width	The zoom is set so that the page's width matches the viewer's width.
PDFViewCtrl.PageViewModes.FitHeight / pdftron.PDF.PageViewModes.e_fit_height	The zoom is set so that the page's height matches the viewer's height.
PDFViewCtrl.PageViewModes.Zoom / pdftron.PDF.PageViewModes.e_zoom	The viewer's zoom is not adjusted based on the page.

You can set a default page fit mode in your PDFViewCtrl by using PageRefViewMode property.

If you want to dynamically change the page fit mode, use PageViewMode property. Note that when the user flips the page, the page view mode will be automatically reset to the default mode set by PageRefViewMode.

// Xamarin.Android
mPdfViewCtrl.PageViewMode = pdftron.PDF.PDFViewCtrl.PageViewModes.FitPage;

// Xamarin.iOS
mPdfViewCtrl.PageViewMode = pdftron.PDF.PageViewModes.FitPage;