Chewie源码

import 'dart:async';

import 'package:chewie/src/chewie_progress_colors.dart';
import 'package:chewie/src/player_with_controls.dart';
import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
import 'package:flutter/widgets.dart';
import 'package:video_player/video_player.dart';

class Chewie extends StatefulWidget {
  /// 视频播放器的控制器
  final VideoPlayerController controller;

  /// 启动时初始化视频，为回放做准备
  final bool autoInitialize;

  /// 视频一显示就播放视频
  final bool autoPlay;

  /// 从某个位置开始录像
  final Duration startAt;

  /// 视频是否可以循环播放
  final bool looping;

  /// 是否显示控件
  final bool showControls;

  /// 视频的宽高比
  final double aspectRatio;

  /// 用于IOS上的控件颜色。默认情况下，iOS使用的颜色样本是iOS11的原始设计
  final ChewieProgressColors cupertinoProgressColors;

  /// 进度条颜色。默认情况下进度条颜色是主题的颜色
  final ChewieProgressColors materialProgressColors;

  /// 视频初始化之前，占位符显示在视频下面
  final Widget placeholder;

  /// 当按下播放按钮后，是否全屏播放
  final bool fullScreenByDefault;
  
  /// 这是构造函数
  Chewie(
    this.controller, {
    Key key,
    this.aspectRatio,
    this.autoInitialize = false,
    this.autoPlay = false,
    this.startAt,
    this.looping = false,
    this.fullScreenByDefault = false,
    this.cupertinoProgressColors,
    this.materialProgressColors,
    this.placeholder,
    this.showControls = true,
  })  : assert(controller != null, 'You must provide a controller to play a video'),
        super(key: key);

  @override
  State createState() {
    return new _ChewiePlayerState();
  }
}

class _ChewiePlayerState extends State {
  /// 视频控制器
  VideoPlayerController _controller;
  /// 是否可以全屏
  bool _isFullScreen = false;

  @override
  Widget build(BuildContext context) {
    return new PlayerWithControls(
      controller: _controller,
      onExpandCollapse: () => _pushFullScreenWidget(context),
      aspectRatio: widget.aspectRatio ?? _calculateAspectRatio(context),
      cupertinoProgressColors: widget.cupertinoProgressColors,
      materialProgressColors: widget.materialProgressColors,
      placeholder: widget.placeholder,
      autoPlay: widget.autoPlay,
      showControls: widget.showControls,
    );
  }

  /// 初始化
  @override
  void initState() {
    super.initState();
    /// 初始化视频控制器
    _controller = widget.controller;
    _initialize();
  }

  Widget _buildFullScreenVideo(BuildContext context, Animation animation) {
    return new Scaffold(
      resizeToAvoidBottomPadding: false,
      body: new Container(
        alignment: Alignment.center,
        color: Colors.black,
        child: new PlayerWithControls(
          controller: _controller,
          onExpandCollapse: () => new Future.value(Navigator.of(context).pop()),
          aspectRatio: widget.aspectRatio ?? _calculateAspectRatio(context),
          fullScreen: true,
          cupertinoProgressColors: widget.cupertinoProgressColors,
          materialProgressColors: widget.materialProgressColors,
        ),
      ),
    );
  }

  Widget _fullScreenRoutePageBuilder(
    BuildContext context,
    Animation animation,
    Animation secondaryAnimation,
  ) {
    return new AnimatedBuilder(
      animation: animation,
      builder: (BuildContext context, Widget child) {
        return _buildFullScreenVideo(context, animation);
      },
    );
  }

  Future _initialize() async {
    //是否可以循环播放
    await _controller.setLooping(widget.looping);
    /// 如果是启动时就初始化视频或者自动播放，那么就用视频控制器去初始化视频
    if (widget.autoInitialize || widget.autoPlay) {
      await _controller.initialize();
    }
    /// 如果是自动播放，且是默认全屏  
    if (widget.autoPlay) {
      if (widget.fullScreenByDefault) {
        _isFullScreen = true;
        ///r如何全屏显示
        await _pushFullScreenWidget(context);
      }

      await _controller.play();
    }
    /// 如果是从视频的某个地方开始播放
    if (widget.startAt != null) {
      /// seekTo是一个视频位置定位方法
      await _controller.seekTo(widget.startAt);
    }
    /// 如果视频默认按下播放按钮就全屏播放
    if (widget.fullScreenByDefault) {
      
      widget.controller.addListener(() async {
        if (await widget.controller.value.isPlaying && !_isFullScreen) {
          _isFullScreen = true;
          await _pushFullScreenWidget(context);
        }
      });
    }
  }

  @override
  void didUpdateWidget(Chewie oldWidget) {
    super.didUpdateWidget(oldWidget);

    if (widget.controller.dataSource != _controller.dataSource) {
      _controller.dispose();
      _controller = widget.controller;
      _isFullScreen = false;
      _initialize();
    }
  }

  Future _pushFullScreenWidget(BuildContext context) async {
    /// 安卓界面
    final isAndroid = Theme.of(context).platform == TargetPlatform.android;
    ///TransitionRoute:具有入口和出口转换的路径。PageRouteBuilder:页面路径构造器
    final TransitionRoute route = new PageRouteBuilder(
      /// 设置路径
      settings: new RouteSettings(isInitialRoute: false),
      ///页面构造器
      pageBuilder: _fullScreenRoutePageBuilder,
    );
    /// SystemChrome:控制操作系统图形界面的特定方面以及它如何与应用程序交互。
    SystemChrome.setEnabledSystemUIOverlays([]);
    if (isAndroid) {
      SystemChrome.setPreferredOrientations([
        DeviceOrientation.landscapeLeft,
        DeviceOrientation.landscapeRight,
      ]);
    }

    await Navigator.of(context).push(route);

    SystemChrome.setEnabledSystemUIOverlays(SystemUiOverlay.values);
    SystemChrome.setPreferredOrientations([
      DeviceOrientation.portraitUp,
      DeviceOrientation.portraitDown,
      DeviceOrientation.landscapeLeft,
      DeviceOrientation.landscapeRight,
    ]);
  }

  double _calculateAspectRatio(BuildContext context) {
    final size = MediaQuery.of(context).size;
    final width = size.width;
    final height = size.height;

    return width > height ? width / height : height / width;
  }
}