以编程方式在MvvmCross中创build和绑定Android Spinners

我正在构build一个需要dynamic生成和绑定Spinner控件的跨平台应用程序。 我可以在iOS和Windows平台上做到这一点,但有Android的问题。 如果我理解正确的话,我必须传递一些参数给MvxSpinner的构造函数 – context和attrs,但我无法弄清楚我该怎么做,应该通过那里。 另外,我不知道如何绑定ItemsSource和SelectedItem。 我想一个新的绑定集必须创build(类似于iOS版本),但我无法在Android上find它。 你可以给我一些方向吗?

这是我从Windows版本的源代码:

private void InputColourAtlasChangedMessageHandler( InputColourAtlasChangedMessage message ) { ColourAtlas selected = message.SelectedColourAtlas; var vm = ViewModel as ColorMatchViewModel; List<ComboBox> newComboboxes = new List<ComboBox>(); var currentCount = ColourPickersContainer.Children.Count; for ( int i = currentCount; i < message.ColourCodePartCount; i++ ) { ComboBox cb = new ComboBox { Margin = new Thickness( 0, 0, 10, 0 ), PlaceholderText = "choose" }; Binding itemsSourceBinding = new Binding(); itemsSourceBinding.Path = new PropertyPath( "ColourPartLists[" + i + "]" ); Binding selectedItemBinding = new Binding(); selectedItemBinding.Path = new PropertyPath( "SelectedColourCodeParts[" + i + "]" ); selectedItemBinding.Mode = BindingMode.TwoWay; cb.Tag = i; ColourPickersContainer.Children.Add( cb ); cb.SetBinding( ComboBox.ItemsSourceProperty, itemsSourceBinding ); cb.SetBinding( ComboBox.SelectedItemProperty, selectedItemBinding ); cb.SelectionChanged += cb_SelectionChanged; BindingOperations.SetBinding( cb, ComboBox.SelectedItemProperty, selectedItemBinding ); newComboboxes.Add( cb ); } while ( ColourPickersContainer.Children.Count > message.ColourCodePartCount ) { ColourPickersContainer.Children.RemoveAt( ColourPickersContainer.Children.Count - 1 ); } _comboboxes = newComboboxes; } void cb_SelectionChanged( object sender, SelectionChangedEventArgs e ) { var cb = sender as ComboBox; int changedIndex = ( int )cb.Tag; if ( e.AddedItems.Count > 0 ) { ( DataContext as ColorMatchViewModel ).ColourCodePartChangedCommand.Execute( changedIndex ); } } 

这里是iOS版本(或多或less做同样的事情 – 虽然它只是清除现有的纺纱器,而不是重复使用它们):

 private void InputColourAtlasChangedMessageHandler( InputColourAtlasChangedMessage message ) { ColourAtlas selected = message.SelectedColourAtlas; ClearPickers(); var currentSet = this.CreateBindingSet<ColorMatchView, ColorMatchViewModel>(); for ( int i = 0; i < message.ColourCodePartCount; i++ ) { var j = i; UIPickerView picker = new UIPickerView(); var pickerViewModel = new MvxPickerViewModel( picker ); picker.Model = pickerViewModel; picker.ShowSelectionIndicator = true; pickerViewModel.SelectedItemChanged += vm_SelectedItemChanged; var textView = new PaddedUITextField( new RectangleF( 10, 50 + i * 40, 300, 30 ) ); Add( textView ); textView.InputView = picker; _pickers.Add( picker ); _textViews.Add( textView ); currentSet.Bind( textView ).For( t => t.Text ).To( "SelectedColourCodeParts[" + i + "]" ); currentSet.Bind( pickerViewModel ).For( p => p.ItemsSource ).To( "ColourPartLists[" + i + "]" ); currentSet.Bind( pickerViewModel ).For( p => p.SelectedItem ).To( "SelectedColourCodeParts[" + i + "]" ); currentSet.Bind( pickerViewModel ).For( p => p.SelectedChangedCommand ).To( vm => vm.ColourCodePartChangedCommand ).CommandParameter( j ); } currentSet.Apply(); UpdateLayout( View.Frame.Size ); } private void ClearPickers() { foreach ( var picker in _pickers ) { var vm = picker.Model as MvxPickerViewModel; vm.SelectedItemChanged -= vm_SelectedItemChanged; picker.RemoveFromSuperview(); } foreach ( var textView in _textViews ) { textView.RemoveFromSuperview(); } _pickers.Clear(); _textViews.Clear(); } 

现在Android版本的部分(而不是function)大纲如下所示:

 private void InputColourAtlasChangedMessageHandler( InputColourAtlasChangedMessage message ) { ColourAtlas selected = message.SelectedColourAtlas; var layout = FindViewById<LinearLayout>( Resource.Id.spinnerList ); ClearPickers(); for ( int i = 0; i < message.ColourCodePartCount; i++ ) { MvxSpinner spinner = new MvxSpinner( Context??, Attrs??); MvxAdapter adapter = new MvxAdapter( this ); spinner.ItemSelected += spinner_ItemSelected; layout.AddView( spinner ); _spinners.Add( spinner ); } } void spinner_ItemSelected( object sender, AdapterView.ItemSelectedEventArgs e ) { var changedIndex = _spinners.IndexOf( sender as MvxSpinner ); ( DataContext as ColorMatchViewModel ).ColourCodePartChangedCommand.Execute( changedIndex ); } private void ClearPickers() { var layout = FindViewById<LinearLayout>( Resource.Id.spinnerList ); foreach ( var spinner in _spinners ) { spinner.ItemSelected -= spinner_ItemSelected; } layout.RemoveAllViews(); _spinners.Clear(); } 

Solutions Collecting From Web of "以编程方式在MvvmCross中创build和绑定Android Spinners"

下面是一个关于如何通过Activity.OnCreate中的代码创build一个mvxspinner的例子:

 _bindingContext = new MvxAndroidBindingContext(this, new LayoutInflaterProvider(LayoutInflater), _viewModel); var view = (LinearLayout)_bindingContext.BindingInflate(Resource.Layout.Main, null); SetContentView(view); var spinner = new MvxSpinner(this, null, new MvxAdapter(this, _bindingContext)); view.AddView(spinner); 

然后,如果你想你的LayoutInflaterProvider可能看起来像这样:

 public class LayoutInflaterProvider : IMvxLayoutInflater { public LayoutInflaterProvider(LayoutInflater layoutInflater) { LayoutInflater = layoutInflater; } public LayoutInflater LayoutInflater { get; private set; } } 

我最初在看这个教程 。