THotPDF.DecodeLoadedImageRegion Method

Decodes an exact source-coordinate rectangle from one loaded image XObject stream into a caller-owned TBitmap

Declaration

function DecodeLoadedImageRegion(AImageStream: THPDFStreamObject;
  RegionLeft, RegionTop, RegionRight, RegionBottom: Integer): TBitmap;

HPDFDoc

Name	Purpose
`AImageStream`	Loaded image XObject stream to decode
`RegionLeft`	Inclusive left source coordinate
`RegionTop`	Inclusive top source coordinate
`RegionRight`	Exclusive right source coordinate
`RegionBottom`	Exclusive bottom source coordinate

Returns a newly allocated bitmap containing the clamped non-empty region, or nil when the image or requested geometry cannot be decoded

The caller owns a non-nil returned bitmap and must free it
Coordinates use the decoded image's top-left raster space and the right and bottom bounds are exclusive
Bounds outside the image are clamped before decoding
JPEG 2000 requests the native decoder region before pixel expansion
This method preserves the full decoded resolution of the region
Other supported image formats decode normally and return the exact cropped region
The loaded-page renderer uses the resolution-aware overload automatically for clipped or downscaled axis-aligned image XObjects