THotPDF.BeginLoadedPageProgressiveRegionRender Method
Begins a resumable loaded-page render whose bitmap covers only the requested PDF user-space window
Deklaration
function BeginLoadedPageProgressiveRegionRender(PageIndex: Integer;
RegionLeft, RegionBottom, RegionRight, RegionTop: Single;
DPI: Integer; CancellationToken: THPDFCancellationToken = nil):
THPDFLoadedPageRenderSession;
Parameter
| Name | Zweck |
|---|---|
PageIndex | Zero-based loaded page index |
RegionLeft | Left edge in PDF user-space points |
RegionBottom | Bottom edge in PDF user-space points |
RegionRight | Right edge in PDF user-space points |
RegionTop | Top edge in PDF user-space points |
DPI | Positive target raster resolution |
CancellationToken | Optional caller-owned token; nil uses OperationCancellationToken |
Verhalten
- The region must have positive width and height and uses the unrotated page user space with a lower-left origin
- The returned bitmap dimensions are the region dimensions scaled by
DPI / 72, with page rotation honoured - The session reuses the cached display list and suppresses only paint objects with conservative bounds proven outside the region
- Graphics state, clipping, paths, text advancement, cancellation, and progressive JPEG continuation remain resumable at operator boundaries
RegionVisiblePaintObjectsandRegionCulledPaintObjectsreport the selection made at session creation