property OnPageNumberChanged: TNotifyEvent;
Fired when the visible page number changes due to scrolling. The Sender parameter references the TPdfView instance that raised the event, so a single handler can serve multiple views by inspecting Sender.
Typical uses include: notify a navigation control that the user is now reading a different page in continuous mode. Because the handler runs on the VCL main thread, you can update form controls and call other VCL APIs directly.
Handlers must return quickly — PDFium rendering and form filling occur on the same thread, and any delay here postpones the next page repaint.
TabStop to True if you want this control to participate in tab-key focus traversal so that keyboard events are delivered.PdfView1.OnPageNumberChanged := MyHandler.Set Cursor / Set Caret calls on TPdfView to keep visual feedback synchronized.
procedure TForm1.PdfViewOnPageNumberChanged(Sender: TObject);
begin
// notify a navigation control that the user is now reading a different page in continuous mode
Caption := Format('OnPageNumberChanged on page %d', [PdfView1.PageNumber]);
end;