android - 如何在 Xamarin Forms 应用程序 (android) 中仅激活 1 个 ListView 项目并禁用其他项目

Question

具有如下所示的 ListView，其中包含代表 Tasks 及其各自 Status 的项目:

TasksPage XAML:

<?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
         xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
         xmlns:local="clr-namespace:iFacilityMob;assembly=iFacilityMob"
         x:Class="iFacilityMob.TasksPage">
<ContentPage.Content>
    ...           
        <ListView 
            Grid.Row="1" 
            Grid.Column="0" 
            Grid.ColumnSpan="2" 
            x:Name="TasksListView" 
            HasUnevenRows="True" 
            SeparatorVisibility="None" 
            SelectionMode="None" 
            IsPullToRefreshEnabled="True"
            Refreshing="TasksListView_OnRefreshing"
            CachingStrategy="RetainElement">
            <ListView.ItemTemplate>
                <DataTemplate>
                    <ViewCell>
                        <local:TaskCardTemplate></local:TaskCardTemplate>
                    </ViewCell>
                </DataTemplate>
            </ListView.ItemTemplate>
        </ListView>
    ...
</ContentPage.Content>

任务卡模板 XAML:

<ContentView xmlns="http://xamarin.com/schemas/2014/forms" 
         xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
         x:Class="iFacilityMob.TaskCardTemplate">
  <ContentView.Content>
    <Frame x:Name="Frame"
           IsClippedToBounds="True"  
           HasShadow="True"  
           Padding="2,5,5,2"  
           BackgroundColor="White" 
           Margin="10"
           CornerRadius="5">
        <Grid>
            <Grid.RowDefinitions>
                <RowDefinition Height="Auto"></RowDefinition>
                <RowDefinition Height="Auto"></RowDefinition>
            </Grid.RowDefinitions>
            <Grid.ColumnDefinitions>
                <ColumnDefinition Width="Auto"></ColumnDefinition>
                <ColumnDefinition Width="Auto"></ColumnDefinition>
                <ColumnDefinition Width="*"></ColumnDefinition>
            </Grid.ColumnDefinitions>

            <!-- Vertical colored bar on the left which indicates the current Status -->
            <BoxView x:Name="BVInitial" Grid.Row="0" Color="Green" IsVisible="{Binding InitialStatus}" Grid.RowSpan="2" Grid.Column="0" WidthRequest="8" Margin="0" CornerRadius="3"/>
            <BoxView x:Name="BVStarted" Grid.Row="0" Color="DarkOrange" IsVisible="{Binding Started}" Grid.RowSpan="2" Grid.Column="0" WidthRequest="8" Margin="0" CornerRadius="3"/>
            <BoxView x:Name="BVPaused" Grid.Row="0" Color="DodgerBlue" IsVisible="{Binding Paused}" Grid.RowSpan="2" Grid.Column="0" WidthRequest="8" Margin="0" CornerRadius="3"/>
            <BoxView x:Name="BVFinished" Grid.Row="0" Color="Black" IsVisible="{Binding Finished}" Grid.RowSpan="2" Grid.Column="0" WidthRequest="8" Margin="0" CornerRadius="3"/>

            <!-- Button Start -->
            <Button Grid.Row="0" Grid.Column="1" x:Name="BtnStartTask" Text="Start" TextColor="White" BackgroundColor="Green" CornerRadius="5" Margin="5,5,0,0" HeightRequest="40"   
                    Clicked="BtnStartTask_OnClicked" IsEnabled="{Binding StartEnabledAndVisible}" IsVisible="{Binding StartEnabledAndVisible}" CommandParameter="{Binding .}" />

            <!-- Button Pause -->
            <Button Grid.Row="0" Grid.Column="1" x:Name="BtnPauseTask" Text="Pause" TextColor="White" BackgroundColor="DodgerBlue" CornerRadius="5" Margin="5,5,0,0" HeightRequest="40"  
                    Clicked="BtnPauseTask_OnClicked"  IsEnabled="{Binding PauseEnabled}" IsVisible="{Binding PauseVisible}" CommandParameter="{Binding . }"  />

            <!-- Button End -->
            <Button Grid.Row="1" Grid.Column="1" x:Name="BtnEndTask" Text="End" TextColor="White" BackgroundColor="Red" CornerRadius="5" Margin="5,0,0,5" HeightRequest="40" 
                    Clicked="BtnEndTask_OnClicked" IsEnabled="{Binding EndEnabled}" CommandParameter="{Binding .}"  />

            ... 
            <!-- The data of each Task, not important in this case -->
        </Grid>
    </Frame>
</ContentView.Content>

通过单击按钮，我可以更改任何 Task 项目的状态和 View 。

private async void BtnStartTask_OnClicked(object sender, EventArgs e)
{
    var btn = (Button)sender;
    if (btn.CommandParameter is TaskViewModel model)
    {
        // Task
        if (model.ModelType == Enums.ModelType.Task.ToString())
        {
            await _api.UpdateStatus(new StatusUpdateDTO
                {ID = model.ID, ModelType = Enums.ModelType.Task.ToString(), StatusID = (int) Enums.TaskStatus.Started});                    
    }
    else// Ticket
    {
        await _api.UpdateStatus(new StatusUpdateDTO
            { ID = model.ID, ModelType = Enums.ModelType.Ticket.ToString(), StatusID = (int)Enums.TicketStatus.Assigned });
    }

   UpdateView(Enums.Buttons.Start);
}

private void UpdateView(Enums.Buttons buttonPressed)
{
    switch (buttonPressed)
    {
        case Enums.Buttons.Start:
            // Hide Start
            BtnStartTask.IsEnabled = false;
            BtnStartTask.IsVisible = false;

            // Show Pause
            BtnPauseTask.IsEnabled = true;
            BtnPauseTask.IsVisible = true;

            // Enable End
            BtnEndTask.IsEnabled = true;
            BtnEndTask.IsVisible = true;

            BVStarted.IsVisible = true;
            BVFinished.IsVisible = false;
            BVInitial.IsVisible = false;
            BVPaused.IsVisible = false;
            break;

        case Enums.Buttons.Pause:
            ...

        case Enums.Buttons.End:

            ...
    }
}

一旦 Task Started，我如何实现这一点，我以某种方式禁用(禁用覆盖和按钮)所有其他 Tasks 和最终在 Activity 任务 Paused 或 Ended 时重新启用它们？

编辑:

任务页面 View 模型:

public class TaskViewModel: INotifyPropertyChanged
{
    public int ID { get; set; }// TaskID or TicketID 
    public string ModelType { get; set; }// Task or Ticket
    public string Title { get; set; }
    public string Description { get; set; }
    public int FloorID { get; set; }
    public string FloorName { get; set; }
    public int AreaID { get; set; }
    public string AreaName { get; set; }
    public int? ScheduledTaskID { get; set; }
    public int? ScheduleID { get; set; }

    private int _statusID { get; set; } // Task Status or TicketTask
    public int StatusID
    {
        get => _statusID;
        set
        {
            _statusID = value;
            OnPropertyChanged();
        }
    }

    public bool ActiveItem => (IsTask && (StatusID == (int) Enums.TaskStatus.Started )) || IsTicket && (StatusID == (int) Enums.TicketStatus.InProgress);

    public bool NotActive => !ActiveItem;

    public List<ProductDTO> Products { get; set; }

    public bool IsTask => ModelType == ModelTypes.Task.ToString();
    public bool IsTicket => ModelType == ModelTypes.Ticket.ToString();

    public bool StartEnabledAndVisible
    {
        get
        {
            if (IsTask && StatusID == (int)Enums.TaskStatus.Created || StatusID == (int) Enums.TaskStatus.Paused)
            {
                return true;
            }

            return IsTicket && StatusID == (int) Enums.TicketStatus.Assigned;
        }
    }

    public bool PauseEnabled
    {
        get
        {
            if (IsTask && StatusID == (int)Enums.TaskStatus.Started)
            {
                return true;
            }

            return IsTicket && StatusID == (int)Enums.TicketStatus.InProgress;
        }
    }

    public bool PauseVisible
    {
        get
        {
            if (IsTask && StatusID == (int)Enums.TaskStatus.Started || StatusID == (int)Enums.TaskStatus.Finished)
            {
                return true;
            }

            return IsTicket && StatusID == (int)Enums.TicketStatus.InProgress || StatusID == (int)Enums.TicketStatus.Closed;
        }
    }

    public bool EndEnabled
    {
        get
        {
            if (IsTask && StatusID == (int)Enums.TaskStatus.Started || StatusID == (int)Enums.TaskStatus.Paused)
            {
                return true;
            }

            return IsTicket && StatusID == (int)Enums.TicketStatus.InProgress || StatusID == (int)Enums.TicketStatus.Assigned;
        }
    }

    public bool InitialStatus => IsTask && StatusID == (int) Enums.TaskStatus.Created || IsTicket && StatusID == (int)Enums.TicketStatus.Assigned;

    public bool Started => IsTask && StatusID == (int)Enums.TaskStatus.Started || IsTicket && StatusID == (int)Enums.TicketStatus.InProgress;

    public bool Paused => IsTask && StatusID == (int)Enums.TaskStatus.Paused || IsTicket && StatusID == (int)Enums.TicketStatus.Assigned;

    public bool Finished => IsTask && StatusID == (int)Enums.TaskStatus.Finished || IsTicket && StatusID == (int)Enums.TicketStatus.Closed;

    public string ProductsLabel
    {
        get
        {
            return Products != null ? string.Join(", ", Products.Select(p => p.Name)) : "";
        }
    }

    public event PropertyChangedEventHandler PropertyChanged;

    protected virtual void OnPropertyChanged([CallerMemberName] string propertyName = null)
    {
        PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
    }

而在 TasksPage 中，父页面:

protected override async void OnAppearing()
{
    _scheduledTasks = new ObservableCollection<TaskViewModel>(_schedule.ScheduledTasks.OrderBy(st => st.Finished));
    TasksListView.ItemsSource = _scheduledTasks;
}

任务页面模型:

public class ScheduleDTO
{
    public int ScheduleID { get; set; }
    public DateTime ScheduleDate { get; set; }
    public int WorkerID { get; set; }
    public bool OnHoliday { get; set; }
    public DateTime StartDatetime { get; set; }
    public DateTime StopDatetime { get; set; }
    public DateTime CurrentDateTime { get; set; }
    public DateTime? LoggedInTime { get; set; }
    public DateTime? LoggedOutTime { get; set; }
    public string LateReason { get; set; }
    public string EarlyLogoutReason { get; set; }
    public string LateLogoutReason { get; set; }

    // This should be the source for the Listview
    public List<TaskViewModel> ScheduledTasks { get; set; }
}

Answer 1

我会建议将所有 View 逻辑放在 View 模型中。它会引发一些重构，但会更加简洁和可扩展。这样做，您只需将委托(delegate)从 TaskPageViewModel 传递到所有 TaskViewModel，这将触发所有其他任务的激活:

public class TaskPageViewModel
{
    IApi _api;

    public TaskPageViewModel(IApi api)
    {
        _api = api;
    }

    List<TaskViewModel> Tasks;

    public void CreateTasks()
    {
        Tasks.Add(new TaskViewModel(OnTaskStatusChanged));

        ...
    }

    private void OnTaskStatusChanged(TaskViewModel selectedViewModel)
    {
        if (selectedViewModel.ModelType == Enums.ModelType.Task.ToString())
        {
            await _api.UpdateStatus(new StatusUpdateDTO
                {ID = selectedViewModel.ID, ModelType = Enums.ModelType.Task.ToString(), StatusID = (int)Enums.TaskStatus.Started});
        }

        var taskStatus = selectedViewModel.Status;
        foreach (var task in Tasks)
        {
            if (selectedViewModel != task)
            {
                task.IsEnable = taskStatus == Status.Pause || taskStatus == Status.End;
            }
        }
    }
}

public class TaskViewModel
{
    private readonly Action<TaskViewModel> _onTaskStatusChanged;

    public TaskViewModel(Action<TaskViewModel> onTaskStatusChanged)
    {
        _onTaskStatusChanged = onTaskStatusChanged;
    }

    public ICommand TaskStatusChangedCommand;

    public bool IsEnable;

    public void TaskStatusChanged()
    {
        _onTaskStatusChanged(this);
    }
}

然后您只需将 StatusChangedCommand 和 IsEnable 属性绑定(bind)到您的按钮和框 View 。您将在父 View 模型中拥有所有业务逻辑(api 调用)。