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[英]How To Create a Grid inside a Listview Binding Xamarin.Forms
[英]Xamarin.Forms Binding whole view inside a grid
我目前正在 Xamarin.Forms XAML 中训练一些绑定和 MVVM。 我有一个带有网格的视图,我想将整个视图作为一个孩子绑定到它。
此外,我正在使用 ZXing.Net.Mobile.Forms 和他们的意见,我想显示。
以编程方式, grid.Children.Add(MyView);
没有问题
但是如何通过 XAML 中的绑定来实现相同的结果?
提前致谢!
我的 Xaml 视图应绑定到:
<?xml version="1.0" encoding="UTF-8"?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
x:Class="ZxingNetMobileTemplate.ScannerView">
<Grid BindingContext="{Binding .}" x:Name="test">
<Grid.RowDefinitions>
<RowDefinition Height="Auto"></RowDefinition>
<RowDefinition Height="*"></RowDefinition>
<RowDefinition Height="*" ></RowDefinition>
</Grid.RowDefinitions>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="*"></ColumnDefinition>
</Grid.ColumnDefinitions>
<StackLayout Orientation="Horizontal">
<Image Source="{Binding ImgSource}" HeightRequest="30" WidthRequest="30" HorizontalOptions="End" VerticalOptions="Start">
<Image.GestureRecognizers>
<TapGestureRecognizer Tapped="OnTorchTapped"></TapGestureRecognizer>
</Image.GestureRecognizers>
</Image>
</StackLayout>
</Grid>
</ContentPage>
我的 Xaml.cs 与视图模型:
public partial class ScannerView : ContentPage
{
public CameraViewModel CameraViewModel { get; private set; }
public ScannerView(IEnumerable<BarcodeFormat> formats = null)
{
InitializeComponent();
BindingContext = CameraViewModel is null ? CameraViewModel = new CameraViewModel(formats) : CameraViewModel;
}
protected override void OnAppearing()
{
base.OnAppearing();
CameraViewModel.ScanAsync();
//test.Children.Add(CameraViewModel.Scanner);
//test.Children.Add(CameraViewModel.Overlay);
SubscribeScanResult();
CameraViewModel.Scanner.IsAnalyzing = true;
CameraViewModel.Scanner.IsScanning = true;
}
}
...
最后但并非最不重要的是我的视图模型,其中属性“扫描仪”和“覆盖”应绑定到 xaml
public class CameraViewModel
{
public ZXingScannerView Scanner { get; private set; }
public ZXingDefaultOverlay Overlay { get; private set; }
public IEnumerable<BarcodeFormat> CustomFormats { get; private set; }
public string ImgSource => Device.RuntimePlatform == Device.Android ? "thunder.png" : "Images/thunder.png";
public CameraViewModel(IEnumerable<BarcodeFormat> formats)
{
CustomFormats = formats;
}
...
}
制作自定义“网格”
XAML
<ContentView
....>
<ContentView.Content>
<Grid x:Name="Grid">
.... here is your default content
</Grid>
</ContentView.Content>
</ContentView>
。CS
[XamlCompilation(XamlCompilationOptions.Compile)]
public partial class View1 : ContentView
{
public static readonly BindableProperty CustomViewProperty = BindableProperty.Create(nameof(CustomView), typeof(View), typeof(View1), null, propertyChanged: OnCustomViewChanged);
public View1()
{
InitializeComponent();
}
public View CustomView
{
get { return (View)GetValue(CustomViewProperty); }
set { SetValue(CustomViewProperty, value); }
}
static void OnCustomViewChanged(BindableObject bindable, object oldValue, object newValue)
{
//x:name Grid xaml
//not sure if you want to clear grid before add new control
//((View1)bindable).Grid.Children.Clear();
((View1)bindable).Grid.Children.Add((View)newValue);
}
}
然后在您的 Xaml 而不是 Grid 中使用 View1 (在我的情况下,请选择一些更好的名称:))。
//not sure if you want to bind Scanner property
<?xml version="1.0" encoding="UTF-8"?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
x:Class="ZxingNetMobileTemplate.ScannerView">
<View1 CustomView="{Binding Scanner}">
</ContentPage>
注意:拥有包含视图的 ViewModel 不是一个好习惯。 想象一下,您想在不同的应用程序中使用这个 ViewModel,比如说 WPF。 你不能,因为它依赖于 Zxing。
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