`pdfSetBlackGenFunction`

Install real prepress ExtGState functions — /TR2 (transfer

BOOL32 __stdcall pdfSetTransferFunction(PPDF IPDF, int32_t Handle, uint8_t* Samples, int32_t NumSamples);
BOOL32 __stdcall pdfSetBlackGenFunction(PPDF IPDF, int32_t Handle, uint8_t* Samples, int32_t NumSamples);
BOOL32 __stdcall pdfSetHalftone(PPDF IPDF, int32_t Handle, double Frequency, double Angle, int32_t SpotFunction);

Delphi

function pdfSetTransferFunction(const IPDF: PPDF; Handle: Integer; Samples: PByte; NumSamples: Integer): LongBool; stdcall;
function pdfSetBlackGenFunction(const IPDF: PPDF; Handle: Integer; Samples: PByte; NumSamples: Integer): LongBool; stdcall;
function pdfSetHalftone(const IPDF: PPDF; Handle: Integer; Frequency, Angle: Double; SpotFunction: Integer): LongBool; stdcall;

Purpose. Install real prepress ExtGState functions — /TR2 (transfer function), /BG2 (black-generation function), and /HT (Type 1 halftone) — on an existing ExtGState resource. Siblings of pdfSetUndercolorRemovalFunction (Color-Space Creation and Color Conversion), sharing the identical sample-array-to-Type-0-function mechanism and the same FindGSByHandle ExtGState registry.

Description. All three are fully implemented (source-commented "G-35: install a real..." for each). pdfSetTransferFunction/ pdfSetBlackGenFunction both require NumSamples >= 2, identical validation to pdfSetUndercolorRemovalFunction.

Parameters.

Parameter	Description
`IPDF`	Document handle.
`Handle`	Handle of an existing ExtGState.
`Samples`, `NumSamples`	(TransferFunction/BlackGenFunction) Sampled function output table, `>= 2` samples required.
`Frequency`, `Angle`, `SpotFunction`	(Halftone) Halftone screen frequency (lpi), angle, and standard spot-function selector.

Return value. True if Handle resolves to a live ExtGState (and, for the sample-based pair, NumSamples >= 2); False otherwise.

See also. pdfSetUndercolorRemovalFunction.

C# (P/Invoke)

wrappers/dotnet/LumasPdf.cs

[return: MarshalAs(UnmanagedType.Bool)]

Area

Core SDK