几个Flutter开发中的常用函数

/** 返回当前时间戳 */  static int currentTimeMillis() {    return new DateTime.now().millisecondsSinceEpoch;  }  /** 复制到剪粘板 */  static copyToClipboard(final String text) {    if (text == null) return;    Clipboard.setData(new ClipboardData(text: text));  }  static const RollupSize_Units = ["GB", "MB", "KB", "B"];  /** 返回文件大小字符串 */  static String getRollupSize(int size) {    int idx = 3;    int r1 = 0;    String result = "";    while (idx >= 0) {      int s1 = size % 1024;      size = size >> 10;      if (size == 0 || idx == 0) {        r1 = (r1 * 100) ~/ 1024;        if (r1 > 0) {          if (r1 >= 10)            result = "$s1.$r1${RollupSize_Units[idx]}";          else            result = "$s1.0$r1${RollupSize_Units[idx]}";        } else          result = s1.toString() + RollupSize_Units[idx];        break;      }      r1 = s1;      idx--;    }    return result;  }

 

/** 返回两个日期相差的天数 */  static int daysBetween(DateTime a, DateTime b, [bool ignoreTime = false]) {    if (ignoreTime) {      int v = a.millisecondsSinceEpoch ~/ 86400000 -          b.millisecondsSinceEpoch ~/ 86400000;      if (v < 0) return -v;      return v;    } else {      int v = a.millisecondsSinceEpoch - b.millisecondsSinceEpoch;      if (v < 0) v = -v;      return v ~/ 86400000;    }  }

 

/** 获取屏幕宽度 */  static double getScreenWidth(BuildContext context) {    return MediaQuery.of(context).size.width;  }  /** 获取屏幕高度 */  static double getScreenHeight(BuildContext context) {    return MediaQuery.of(context).size.height;  }  /** 获取系统状态栏高度 */  static double getSysStatsHeight(BuildContext context) {    return MediaQuery.of(context).padding.top;  }