property PageZoom: Double;
Read-only zoom required to fit the current page into the view at the current DisplayMode.
Combine with PageWidthZoom / PageHeightZoom / ActualSizeZoom to build custom fit buttons.
All TPdfView display properties trigger a repaint when assigned; you can change several in sequence without flicker because the redraw is coalesced into a single invalidation.
Active := True.PdfView1.Pdf at runtime, re-apply any view-only settings — the new TPdf has its own state.
begin
PdfView1.PageZoom := {value};
PdfView1.Active := True;
end;