FontHandle 屬性

FontHandle returns the raw PDFium font pointer (FPDF_FONT) associated with the text page object at the supplied index. Internally the value is what PDFium returns from FPDFTextObj_GetFont; most of the other Font* properties on TPdf — FontAscent, FontDescent, FontFamilyName, FontBaseName, FontIsEmbedded, FontItalicAngle, FontWeight, FontData — are convenience wrappers built on top of it.

The index is a 0-based page-object index in the range 0..ObjectCount - 1. Only objects of type text carry a font; for image, path, or shading objects the call returns nil. A page must be active before reading the property.

The returned handle is owned by PDFium and remains valid only while the current page is loaded. Do not free it, do not store it across page changes, and do not call destructive PDFium APIs against it — treat it as an opaque, read-only token.

• The returned pointer becomes invalid as soon as the page is unloaded (e.g. when PageNumber changes) — never cache it.
• Always test for nil before passing the handle to a raw FPDFFont_* import.
• This property is the bridge to PDFium APIs that have no Pascal wrapper yet, e.g. FPDFFont_GetFlags or FPDFFont_GetFontBBox.
• Two different page objects may share the same handle when they reference the same font dictionary in the PDF.
• Reading the property pins the underlying font for the lifetime of the call; PDFium does not reference-count the handle, so plan your work accordingly.