x_at()

MAYAFLUX_API PenPosition MayaFlux::Portal::Text::x_at	(	std::string_view	text,
		GlyphAtlas &	atlas,
		size_t	byte_offset,
		float	pen_x = 0.F,
		float	pen_y = 0.F,
		uint32_t	wrap_w = 0,
		uint32_t	tab_width = 4
	)

Pen position immediately before byte_offset, in lay_out()'s space.

Re-lays-out the text up to byte_offset (clamped to text.size()) with the same pen origin, wrap_w, and tab_width the caller used to produce the original layout, and returns the resulting final_pen_x/final_pen_y. Wrap decisions before a given offset only depend on codepoints before it, so this reproduces the exact pen position lay_out() would have held at that point in the original call - including on a space, tab, newline, wrapped line start, or the very end of the text, none of which index_at()'s quad-based sibling has a quad to answer from.

This re-walks the prefix on every call rather than caching intermediate pen positions; fine for interactive caret placement, not meant for a tight per-frame loop over long text.

Parameters

text	Source UTF-8 string to re-lay-out a prefix of.
atlas	GlyphAtlas to query (same one the original layout used).
byte_offset	Codepoint-boundary byte offset to resolve.
pen_x	Pen origin x, matching the original lay_out() call.
pen_y	Pen origin y, matching the original lay_out() call.
wrap_w	Wrap column, matching the original lay_out() call.
tab_width	Tab stop width, matching the original lay_out() call.

Returns

Pen position immediately before byte_offset.

Definition at line 345 of file TypeSetter.cpp.

{
    const size_t clamped = std::min(byte_offset, text.size());
    const LayoutResult prefix = lay_out(text.substr(0, clamped), atlas, pen_x, pen_y, wrap_w, tab_width);
    return { .x = prefix.final_pen_x, .y = prefix.final_pen_y };
}

References MayaFlux::Portal::Text::LayoutResult::final_pen_x, MayaFlux::Portal::Text::LayoutResult::final_pen_y, and lay_out().

Referenced by MayaFlux::Portal::Text::TextRun::caret(), and index_at().

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