XAML .NET MAUI CarouselView更改位置不工作,除非至少滑动一次

nvbavucw  于 2022-12-16  发布在  .NET
关注(0)|答案(1)|浏览(136)

我正在尝试使用转盘视图创建一个入职视图。我有一个位置指示器和一个按钮来更改转盘视图项目。当我按下按钮时,它应该显示下一个项目。或者,如果我单击指示器,它也应该更改项目!
问题是,如果不滑动视图至少一次或从UI将位置设置为零(通过转到任意位置并按下指示器的第一个索引),我无法控制它的位置。

下面是我的CaouselView XAML

<Grid RowDefinitions="*,Auto">
        <CarouselView x:Name="OnBoardingCarouselView"
                      HorizontalOptions="FillAndExpand"
                      VerticalOptions="FillAndExpand"
                      IsBounceEnabled="False"
                      Loop="False" ItemsSource="{Binding IntroScreens}"
                      PositionChangedCommand="{Binding HandlePositionChangedCommand}"
                      PositionChangedCommandParameter="{Binding Source={RelativeSource Self}, Path=Position}"
                      IndicatorView="CarouselIndicator"
                      Position="{Binding CarouselPosition, Mode=TwoWay}">
            <CarouselView.ItemTemplate>
                <DataTemplate x:DataType="models:IntroScreen">
                    <Grid RowDefinitions="60*,40*">
                        <Image Source="{Binding Image}" HeightRequest="200"></Image>
                        <VerticalStackLayout Grid.Row="1">
                            <Label Text="{Binding IntroTitle}"
                                   FontSize="Title"></Label>
                            <Label Text="{Binding IntroDescription}"
                                   FontSize="Body"></Label>
                        </VerticalStackLayout>
                    </Grid>
                </DataTemplate>
            </CarouselView.ItemTemplate>
        </CarouselView>
        <Grid Grid.Row="1" ColumnDefinitions="*,Auto">
            <IndicatorView x:Name="CarouselIndicator" Grid.Column="0"
                           IndicatorsShape="Circle"
                           IndicatorSize="12"
                           IndicatorColor="{StaticResource Secondary}"
                           SelectedIndicatorColor="{StaticResource Primary}"
                           VerticalOptions="Center"></IndicatorView>
            <StackLayout Grid.Column="1">
                <Button x:Name="NextButton" Text="Next" 
                        Command="{Binding HandleNextButtonClickCommand}"
                        IsVisible="{Binding NextButtonVisibility}"></Button>
                <Button x:Name="EnterButton" Text="Enter" 
                        Command="{Binding HandleEnterButtonClickCommand}"
                        IsVisible="{Binding EnterButtonVisibility}"></Button>
            </StackLayout>
        </Grid>

我试过像这样设置起始位置,但不起作用-

public IntroScreenView()
    {
        InitializeComponent();

        // Check if the position preset is working
        OnBoardingCarouselView.Position = 1;
    }

下面是我对应的视图模型-

[ObservableObject]
    public partial class IntroScreenViewModel
    {
        [ObservableProperty]
        private int carouselPosition;
        [ObservableProperty]
        private bool nextButtonVisibility;
        [ObservableProperty]
        private bool enterButtonVisibility;
        [ObservableProperty]
        private ObservableCollection<IntroScreen> introScreens;

        public IntroScreenViewModel()
        {
            EnterButtonVisibility = false;
            NextButtonVisibility = true;
            IntroScreens = new ObservableCollection<IntroScreen>
            {
                new()
                {
                    IntroTitle = "Intro Title One",
                    IntroDescription = "Lorem is some time ipsum but ipsum can't be lorem.",
                    Image = "cr_1.svg"
                },
                new()
                {
                    IntroTitle = "Intro Title Two",
                    IntroDescription = "Lorem is some time ipsum but ipsum can't be lorem.",
                    Image = "cr_2.svg"
                },
                new()
                {
                    IntroTitle = "Intro Title Three",
                    IntroDescription = "Lorem is some time ipsum but ipsum can't be lorem.",
                    Image = "cr_3.svg"
                }
            };
            // commenting the following line or setting to any position 
            // does not affect anything
            CarouselPosition = 0;
        }
        [RelayCommand]
        public void HandlePositionChanged(int position)
        {
            // here position variable always gets the correct position
            if (position == IntroScreens.Count - 1)
            {
                EnterButtonVisibility = true;
                NextButtonVisibility = false;
            }
            else
            {
                EnterButtonVisibility = false;
                NextButtonVisibility = true;
            }
        }
        [RelayCommand]
        public void HandleNextButtonClick()
        {
            if (CarouselPosition + 1 < introScreens.Count)
                CarouselPosition++;
        }

        [RelayCommand]
        public void HandleEnterButtonClick()
        {
            Application.Current!.MainPage = new LoginPageView();
        }
    }

完整的源代码在这里https://github.com/MahmudX/Binimoy

vs91vp4v

vs91vp4v1#

我也遇到了这个问题,经过几个小时的实验,我意识到问题出在循环属性上。
CarouselView中设置Loop="True"可解决此问题。
不管怎样,这是毛伊虫。

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