64 lines
2.1 KiB
Dart
Executable File
64 lines
2.1 KiB
Dart
Executable File
import 'package:get/get.dart';
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/// 导航栏透明度管理 Mixin
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/// 用于统一管理页面导航栏的透明度变化
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mixin KRAppBarOpacityMixin {
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/// 导航栏透明度值
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final RxDouble kr_appBarOpacity = 0.0.obs;
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/// 上次滚动位置
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double _lastOffset = 0;
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/// 上次更新时间
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double _lastUpdateTime = 0;
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/// 滚动阈值
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static const double _scrollThreshold = 100.0;
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/// 最小透明度
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static const double _minOpacity = 0.0;
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/// 最大透明度
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static const double _maxOpacity = 1.0;
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/// 滚动速度因子
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static const double _scrollSpeedFactor = 0.5;
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/// 更新导航栏透明度
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/// [scrollPixels] 当前滚动位置
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void kr_updateAppBarOpacity(double scrollPixels) {
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final currentTime = DateTime.now().millisecondsSinceEpoch.toDouble();
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final deltaTime = currentTime - _lastUpdateTime;
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_lastUpdateTime = currentTime;
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// 计算滚动速度
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final scrollDelta = scrollPixels - _lastOffset;
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final scrollSpeed = scrollDelta.abs() / (deltaTime > 0 ? deltaTime : 1);
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_lastOffset = scrollPixels;
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// 根据滚动位置计算基础透明度
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double baseOpacity = 0.0;
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if (scrollPixels <= 0) {
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baseOpacity = _minOpacity;
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} else if (scrollPixels >= _scrollThreshold) {
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baseOpacity = _maxOpacity;
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} else {
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// 使用平滑的插值函数计算透明度
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baseOpacity = (scrollPixels / _scrollThreshold).clamp(_minOpacity, _maxOpacity);
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// 使用平方根函数使透明度变化更加平滑
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baseOpacity = baseOpacity * baseOpacity;
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}
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// 根据滚动速度调整透明度
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double speedFactor = (scrollSpeed * _scrollSpeedFactor).clamp(0.0, 0.5);
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double targetOpacity = baseOpacity + (speedFactor * 0.2); // 减小速度影响
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// 平滑过渡到目标透明度
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final currentOpacity = kr_appBarOpacity.value;
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final opacityDelta = targetOpacity - currentOpacity;
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final smoothFactor = 0.3; // 平滑因子，值越小过渡越平滑
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kr_appBarOpacity.value = (currentOpacity + opacityDelta * smoothFactor)
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.clamp(_minOpacity, _maxOpacity);
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}
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} |