`pdfDrawTextArc`

Draw text along a circular arc — the real curved-baseline

Category	Text output (curved baseline)
Note	`DrawOptions` is reserved/unused

Purpose — Draw text along a circular arc — the real curved-baseline writer that pdfWriteAngleText's Radius/YOrigin parameters looked like they should provide, but don't.

Description — Places the first glyph at Angle degrees around the circle centered at (XPos, YPos) with radius Radius, advancing counter-clockwise; each subsequent glyph's angular position is advanced by glyphWidth / Radius (arc length → subtended angle), and each glyph is individually drawn via pdfWriteAngleText rotated tangent to the circle (+90° from the radial angle, "upright outward"). This means arc text inherits the same weaker Unicode-encoding behavior documented for pdfWriteAngleText in E01 — non-TrueType glyphs go through the ambient CP_ACP code page, not the WinAnsi-safe path.

Declarations

int32_t __stdcall pdfDrawTextArc(PPDF IPDF, double XPos, double YPos, double Radius, double Angle, const char* Text, int32_t DrawOptions);
int32_t __stdcall pdfDrawTextArcA(PPDF IPDF, double XPos, double YPos, double Radius, double Angle, const char* Text, int32_t DrawOptions);
int32_t __stdcall pdfDrawTextArcW(PPDF IPDF, double XPos, double YPos, double Radius, double Angle, const wchar_t* Text, int32_t DrawOptions);

Delphi

function pdfDrawTextArcA(const IPDF: PPDF; XPos, YPos, Radius, Angle: Double; Text: PAnsiChar; DrawOptions: Integer): Integer; stdcall; external 'LumasPdf.dll';
function pdfDrawTextArcW(const IPDF: PPDF; XPos, YPos, Radius, Angle: Double; Text: PWideChar; DrawOptions: Integer): Integer; stdcall; external 'LumasPdf.dll';

Parameters

Parameter	Type	Description
`IPDF`	`PPDF`	Instance handle with an open page and selected font.
`XPos`, `YPos`	`Double`	Arc center.
`Radius`	`Double`	Arc radius; must be `> 0` or the call fails.
`Angle`	`Double`	Starting angle in degrees for the first glyph.
`Text`	string	Text to place along the arc, one glyph at a time.
`DrawOptions`	`Integer`	Accepted for ABI compatibility; the source comment marks it explicitly "reserved" and it is not read anywhere in the implementation.

Return value — 1 on success; 0 if no page is open, no font is selected, Radius <= 0, or Text is empty.

See also — pdfWriteAngleText

C# (P/Invoke)

wrappers/dotnet/LumasPdf.cs

public static extern int pdfDrawTextArcW(IntPtr IPDF, double XPos, double YPos, double Radius, double Angle, IntPtr Text, int DrawOptions);
public static extern int pdfDrawTextArc(IntPtr IPDF, double XPos, double YPos, double Radius, double Angle, IntPtr Text, int DrawOptions);
public static extern int pdfDrawTextArcA(IntPtr IPDF, double XPos, double YPos, double Radius, double Angle, IntPtr Text, int DrawOptions);

Area

Text