38 lines
1.4 KiB
Dart
38 lines
1.4 KiB
Dart
import 'package:flutter/widgets.dart';
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/// Scroll the nearest scrollable ancestor so [context] is centered.
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///
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/// Uses [Scrollable.ensureVisible] with alignment 0.5 (center).
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/// Runs in a post-frame callback to ensure layout is complete.
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void scrollContextToCenter(BuildContext? context) {
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if (context == null) return;
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WidgetsBinding.instance.addPostFrameCallback((_) {
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if (!context.mounted) return;
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Scrollable.ensureVisible(context, alignment: 0.5, duration: const Duration(milliseconds: 200), curve: Curves.easeOut);
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});
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}
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/// Scroll a horizontal list to center the item at the given index.
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///
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/// Assumes items are laid out with [leadingPadding] before the first item,
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/// and each item occupies [itemExtent] pixels (including per-item padding).
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void scrollListToIndex(
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ScrollController controller,
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int index, {
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required double itemExtent,
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double leadingPadding = 12.0,
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bool animate = true,
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}) {
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if (!controller.hasClients || itemExtent <= 0) return;
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final viewport = controller.position.viewportDimension;
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final targetCenter = leadingPadding + (index * itemExtent) + (itemExtent / 2);
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final desiredOffset = (targetCenter - (viewport / 2)).clamp(0.0, controller.position.maxScrollExtent);
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if (animate) {
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controller.animateTo(desiredOffset, duration: const Duration(milliseconds: 150), curve: Curves.easeOut);
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} else {
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controller.jumpTo(desiredOffset);
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}
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}
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