Module text 

Font atlas data and text draw-call assembly. No backend ownership; the renderer uploads the atlas textures; this module only builds the quad geometry from TextLabel components each frame.

Structs

FontSet

The faces a frame draws with: every font loaded at init, keyed by handle, plus the face a label naming no font of its own falls back to.

LoadedFont

Per-font data kept in memory after init() so step() can build text quads each frame.

Functions

build_text_calls

Build one TextDrawCall per TextLabel, laying out character quads using the loaded font metrics. When win_w and win_h are both > 0.0, labels with centered = true are repositioned to the centre of the viewport. clips maps an element id to a reference-space clip band; a label found there has its call scissored to that band (mapped to the window), so a scrollable panel’s off-band rows do not bleed over its chrome.

build_text_calls_into

build_text_calls, appending onto an existing draw list so a caller assembling a frame from several element groups reuses one buffer (and, in steady state, the pooled geometry of the spent frame it recycled).

derive_cap_px

Cap height (logical px) for vertical centering: the bearing of an uppercase reference glyph (‘H’), falling back to the tallest uppercase glyph, then to a fraction of the em when no metrics are available.

measure_label_box

Measure a label’s background-box extent for layout: a box hugging the visible glyphs grown by the label’s padding on every side, plus one line height per extra \n-split line. Mirrors the background-box math in build_text_calls. top_inset is the gap from the box top down to the text origin (the label’s y), which LayoutContainer uses to place the box. Returns None for a hidden label, or one with no font to draw with at all, so a LayoutContainer drops it and reserves no space.

text_advance_width

Advance width of content in scaled pixels for the given font, for placing a caret, sizing a field’s text, or centring a line. Newlines carry no advance, so a multi-line string measures as if its lines were concatenated.

widest_line_width

Width of the widest line of content in scaled pixels: what a label’s background box and its centre / right alignment are both sized against.

Type Aliases

FontMetrics

One face’s per-glyph metrics, keyed by Unicode code point.