fix(geometry): resolve transform lengths per axis and per font-size - #286
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LeadcodeDev merged 1 commit intoSep 22, 2026
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`apply_transform_chain` resolves `translate`/`translateX`/`translateY` lengths through this context. The paint pass resolves the very same functions through `LengthContext { ..., parent_size: box_layout.width.max(height), font_size: node.css.font_size_px_or(16.0), ... }` and then splits it into per-axis `length_ctx_x`/`length_ctx_y` (crates/rustmotion-core/src/engine/paint_pass.rs:229-250, used at :953-962). Two divergences: (a) `em` — a `font-size: 96px` text with `transform: "translateX(-10em)"` is moved -960px by the renderer but only -160px by the validator, so a component at x=200 that renders at x=-760 (fully off-frame) validates clean; (b) percentage translate — the validator uses `max(w, h)` on both axes, the exact mistake paint_pass.rs:236-242 calls out in a comment ("never max(width, height) on both axes"), which over-estimates on the short axis and produces false positives. Note the `--strict-anim` path funnels animated transforms through this same function (geometry.rs:1482), so it inherits both errors.
Refs #220
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…286) `apply_transform_chain` resolves `translate`/`translateX`/`translateY` lengths through this context. The paint pass resolves the very same functions through `LengthContext { ..., parent_size: box_layout.width.max(height), font_size: node.css.font_size_px_or(16.0), ... }` and then splits it into per-axis `length_ctx_x`/`length_ctx_y` (crates/rustmotion-core/src/engine/paint_pass.rs:229-250, used at :953-962). Two divergences: (a) `em` — a `font-size: 96px` text with `transform: "translateX(-10em)"` is moved -960px by the renderer but only -160px by the validator, so a component at x=200 that renders at x=-760 (fully off-frame) validates clean; (b) percentage translate — the validator uses `max(w, h)` on both axes, the exact mistake paint_pass.rs:236-242 calls out in a comment ("never max(width, height) on both axes"), which over-estimates on the short axis and produces false positives. Note the `--strict-anim` path funnels animated transforms through this same function (geometry.rs:1482), so it inherits both errors. Refs #220
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Audit finding carried by this chantier. Refs #220 (RM-15).