42 lines
1.5 KiB
Dart
42 lines
1.5 KiB
Dart
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import 'dart:collection';
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import 'package:flutter/painting.dart';
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typedef _Key = (String, TextStyle, TextScaler, TextDirection);
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final LinkedHashMap<_Key, Size> _sizes = LinkedHashMap<_Key, Size>();
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const int _maxEntries = 512;
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/// Size of [text] laid out on one unconstrained line, memoized per
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/// (text, style, scaler, direction).
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///
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/// Metadata strips measure every field before building it so they can shed
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/// parts that will not fit (#1893), and fitted titles need a line height to
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/// know whether a box can overflow at all; each such measurement shapes a
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/// string the render tree is about to shape again. Shaping dominates the TV
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/// spotlight's info swap on low-end boxes, and the measured strings repeat
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/// heavily — separators, "Movie", "TV-14", years, runtimes, "88%" — so a
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/// small cache turns the measuring pass into hash lookups. Bounded and
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/// insertion-ordered: the oldest entry goes first.
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Size cachedSingleLineTextSize(
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String text, {
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required TextStyle style,
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required TextScaler textScaler,
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required TextDirection textDirection,
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}) {
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final key = (text, style, textScaler, textDirection);
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final cached = _sizes[key];
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if (cached != null) return cached;
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final painter = TextPainter(
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text: TextSpan(text: text, style: style),
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textDirection: textDirection,
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textScaler: textScaler,
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maxLines: 1,
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)..layout();
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final size = painter.size;
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painter.dispose();
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if (_sizes.length >= _maxEntries) _sizes.remove(_sizes.keys.first);
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_sizes[key] = size;
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return size;
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}
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