text_autosize 0.3.2

text_autosize: ^0.3.2 copied to clipboard

• Correct the mechanism in the 0.3.1 note, which said each fit check "accepted the resulting NaN metrics because comparisons against NaN are false". I instrumented the shipped fit check to check that, and it is not what happens. The scaled font size is indeed NaN (0 × Infinity), but Flutter does not lay that out to NaN metrics: it sanitises the degenerate layout to a zero-size one (measured width 0.0, height 1.0), and the fit check accepts it the ordinary way — a zero-size layout fits any box — so the search stops at the smallest candidate and renders at that size. The NaN never reaches the comparison. The observed defect (fontSize: 0 rendering at 4.0 instead of 0.0, with minFontSize: 4) and the fix are unchanged; only the explanation was wrong, and it came from an unverified guess about what the engine does with a NaN size. The > comparison against NaN is a genuine hazard, but it is not the one this bug hit.

• Correct the description of the 0.3.0 fix. That entry said the NaN layout could leave a later, ordinary AutoSizeText unable to return from layout. I took that from a bug report without reproducing it myself, and I cannot: removing the guard again and pumping a degenerate widget followed by an ordinary one — separately, in one tree, and with a 5000-character string — finishes in seconds every time. The claim was not mine to make and it is withdrawn.

  What 0.3.0 actually fixed, measured before and after: with TextStyle(fontSize: 0), minFontSize: 4 and maxFontSize: 40, the widget used to render at 4.0 — it divided by the zero base, every probe scaled the span by an infinite ratio, and each fit check accepted the resulting NaN metrics because comparisons against NaN are false, so the search returned a size the caller never asked for. It now renders at 0.0, which is exactly what a plain Text does with the same style. Silently substituting a different size in a package whose contract is "behaves like Text" is the real defect, and it is fixed; nothing was hanging.

• Fix a hang reachable from a legal style. TextStyle(fontSize: 0) — which a plain Text renders without complaint — made every fit probe scale the span by candidate / 0. The resulting infinite ratio laid out text at NaN sizes, and because each fit check compares against NaN (where every comparison is false) the probe reported that it fitted. Worse than the wrong answer, that NaN layout left the text engine in a state where a later, ordinary AutoSizeText could stop returning from layout entirely. A zero, negative or infinite base now skips the ratio machinery and renders at the size the caller asked for, which is what Text does. Covered by tests, including one that pumps an ordinary widget afterwards to prove nothing is wedged.
• Mark AutoSizeGroup as final. Its entire contract is private, so an external implements AutoSizeGroup compiled but was guaranteed to fail with NoSuchMethodError the moment a widget used it. AutoSizeText is deliberately left open: it is a drop-in for auto_size_text, whose AutoSizeText is open, as is Flutter's own Text, and subclassing a text widget to preset its style is a real pattern this should not break.
• Remove a stray # Changelog heading from the middle of this file.

• Add back a deprecated textScaleFactor parameter on AutoSizeText and AutoSizeText.rich. The 0.1.0 release dropped it, which broke the drop-in claim: any call site that set textScaleFactor failed to compile. It now compiles again and maps to TextScaler.linear(factor). Prefer textScaler; textScaleFactor is deprecated and will be removed later. Setting both asserts in debug builds.

• Install instructions now say pub add instead of pinning a version. The pinned number was stale by several releases and would have been stale again after the next one: the README ships frozen in the archive, so a hand-edited version line is wrong the moment anything is published. This one cannot go out of date.

• Docs: tightened the README wording and visuals.

• Expand the package description to name what the package does in the words people search for. No code changes.

Initial release. The API follows auto_size_text 3.0.0, with these changes:

• textScaler replaces textScaleFactor. The fitted font size accounts for the ambient MediaQuery scaler, including nonlinear scalers.
• Rich text is measured with the fully resolved style, matching how Text.rich renders it.
• Measurement resolves textAlign and textDirection like the rendered Text instead of assuming left-aligned, left-to-right text.
• A single TextPainter is reused for all fit measurements of a widget.
• textWidthBasis, textHeightBehavior and selectionColor are passed through to the built Text.
• presetFontSizes are asserted to be in descending order.