BitmapCount Propriété

BitmapCount renvoie le nombre d’objets image de page sur la page actuellement active (section 8.9 de la spécification PDF 1.7). Il se combine avec l’indexeur Bitmap[Index], which decodes the underlying image stream into a fully rendered Delphi TBitmap (32-bit RGBA, ready for Canvas.Draw, clipboard transfer, or saving to PNG/BMP).

The value is 0 when Active is False, when PageNumber est invalide, ou lorsque la page ne contient aucun objet image. Le comptage est identique à ImageCount; les deux propriétés ne diffèrent que par le type de retour de leurs indexeurs — Image[Index] hands back the raw decoded pixel buffer in a TPdfImage record, whereas Bitmap[Index] wraps that buffer into a managed VCL TBitmap owned by the caller.

The typical loop is for I := 0 to Pdf.BitmapCount - 1 do followed by Pdf.Bitmap[I]. Each access allocates a new TBitmap and copies pixels — do not call it in tight rendering loops; cache the bitmap when reused Free each returned bitmap when finished to release GDI resources promptly.

• Image masks (soft masks, stencil masks) are merged into the decoded TBitmap alpha channel automatically by PDFium.
• If you only need pixel data for export (PNG/JPEG/etc.) and not for drawing, ImageCount / Image[Index] avoids the GDI bitmap allocation overhead.
• A page’s BitmapCount is not affected by zoom level, viewport, or page rotation — it is a structural property of the page content stream.