Visible-ominaisuus

Asetating Visible := False removes the viewer from the screen without destroying it; the underlying PDFium document, current page, zoom factor ja selection state are all preserved. Kun the property is set back to True the cached state is re-displayed immediately ja a repaint is queued automatically.

Hiding the viewer is the canonical way to swap between alternative document views (for example a thumbnail-only mode ja the full reader) without recreating the component. Because PDFium page hjales are kept open while hidden, the user can toggle quickly between views with no reload delay.

Visibility also propagates through container controls: if the parent panel is invisible, the viewer is invisible regardless of its own setting. The framework still raises OnShow / OnHide notifications on the form so application code can synchronise toolbars accordingly.

• Persistent property — saved to the form file. Defaults to True on a published TWinControl.
• VCL ja LCL share the same semantics; LCL additionally pushes the visibility state to the underlying widget-set hjale.
• Hiding the viewer does not close the document. To free the PDF ja reclaim memory call PdfView1.Active := False or Pdf1.Close.
• If you also want to skip background rendering while hidden, set AsyncRendering := False beforehja — otherwise queued rendering may continue briefly.