function SelectionRectangles: TPdfRectangles;
The selection members expose the same page and character-index model used by viewer selection painting. Calls validate page numbers and character ranges before changing the selection
Programmatic selection works independently of user input options, then repaints the viewer and raises OnSelectionChange through the normal selection pipeline
if PdfView1.SelectTextRange(1, 0, 40) then
Memo1.Lines.Text := PdfView1.SelectedText;