property PageHeight: Double; // read only
PageHeight returns the height of the currently active page in PDF default user
space units, where 1 unit = 1/72 of an inch (1 point). The value reflects the
page’s effective MediaBox after rotation has been applied — a 595 ×
842 point A4 page rotated 90° reports PageWidth = 842 and
PageHeight = 595.
The value is 0 when Active is False. Page
sizes in PDF are doubles, not integers; A4 is exactly 841.8898 points
tall (210 mm ÷ 25.4 × 72), letter is 792. Multiply by
25.4 / 72 to convert to millimetres, or by 1 / 72 for inches.
Apply Zoom (TPdfView) to translate user-space to screen pixels.
The dimensions come from the page’s MediaBox unless the PDF specifies a
smaller CropBox / TrimBox / BleedBox / ArtBox. Use PageBox[Box] to read
any of the alternative boxes explicitly — print workflows typically operate on
TrimBox or BleedBox rather than MediaBox.
PageRotation is assigned: PDFium swaps width / height
automatically for 90° / 270° rotations.PageNumber.
var WidthMM, HeightMM: Double;
Pdf1.Active := True;
Pdf1.PageNumber := 1;
WidthMM := Pdf1.PageWidth * 25.4 / 72;
HeightMM := Pdf1.PageHeight * 25.4 / 72;
Label1.Caption := Format('Page 1: %.1f x %.1f mm', [WidthMM, HeightMM]);