Redraws the tiles of a page that show area in layers, after an edit changed what they show
(an annotation added, moved or removed, a field's value). A tile on the surface that is still wanted stays there, and in
GetFrame(in Viewport, Span<FramePart>), until its redraw replaces it (Invalidated), so the edit never shows a blank
frame; one no longer wanted leaves the surface; renders in progress restart.
public int Invalidate(int pageIndex, PdfRectangle area, DisplayLayers layers)
The zero-based page.
The changed area in the page's default user space.
The layers that changed (Annotations for an annotation edit).
Spec #33 viewer capability 6. Annotations drawn with NoZoom or NoRotate (ISO 32000-2 §12.5.3) leave their rectangle: invalidate the whole page (Invalidate(Int32, DisplayLayers)) for them.