Bitmap property

この API エントリでは識別子、シグネチャ、コードブロック、PDF 用語を元の表記のまま保持します。

Returns a freshly-decoded VCL TBitmap holding the raster data of the specified image object on the current page. The bitmap is newly allocated on each call; the caller owns it and is responsible for calling Free.

Bitmap returns a TBitmap containing the pixel data of the n-th raster image on the current page. PDFium decodes the underlying stream (JPEG, JPEG2000, CCITT, JBIG2, or FlateDecode pixel data) and PDFiumVCL converts the result into a VCL TBitmap at the image's stored resolution, with alpha preserved as a 32-bit ARGB surface where the source provides a soft mask.

Every call allocates a fresh bitmap; the property does not cache. This makes the property safe to call from worker threads but means callers must always free the returned object, typically inside a try .. finally block.

When you also need the image's on-page transformation matrix and bounding rectangle use Image[Index] instead — it returns a record that bundles the same TBitmap with positional metadata. The shape-agnostic sibling ObjectBitmap[ObjectIndex] indexes into the full page-object array (mixed text, paths, images) and returns the same bitmap if the targeted object happens to be an image.

• For PDFs containing thousands of small images, prefer iterating in batches and freeing each bitmap promptly to limit peak memory.
• The returned bitmap has no DPI suggestion encoded; size it against the source resolution if you need to print at the page's nominal output size.
• Use the page's coordinate transform from Image if you intend to place the bitmap back at the original on-page location.
• Returns nil when Index is out of range or when the document is not active.

BitmapCount, Image, ImageCount, ObjectBitmap