我想将Tap和Long Tap与Custom Gridview一起使用。
点击正在工作，但长按不起作用。
一键关闭长按也可以使用。
请帮助我。
谢谢。
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public class GridView : Grid
{
public static readonly BindableProperty ItemsSourceProperty = BindableProperty.Create(nameof(ItemsSource), typeof(IList), typeof(GridView), default(IList), BindingMode.TwoWay);
public static readonly BindableProperty ItemTappedCommandProperty = BindableProperty.Create(nameof(ItemTappedCommand), typeof(ICommand), typeof(GridView), null);
public static readonly BindableProperty ItemLongTappedCommandProperty = BindableProperty.Create(nameof(ItemLongTappedCommand), typeof(ICommand), typeof(GridView), null);
public static readonly BindableProperty ItemTemplateProperty = BindableProperty.Create(nameof(ItemTemplate), typeof(DataTemplate), typeof(GridView), default(DataTemplate));
public static readonly BindableProperty MaxColumnsProperty = BindableProperty.Create(nameof(MaxColumns), typeof(int), typeof(GridView), 2);
public static readonly BindableProperty TileHeightProperty = BindableProperty.Create(nameof(TileHeight), typeof(float), typeof(GridView), 220f);//adjusted here reuired height
public GridView()
{
PropertyChanged += GridView_PropertyChanged;
PropertyChanging += GridView_PropertyChanging;
}
public IList ItemsSource
{
get { return (IList)GetValue(ItemsSourceProperty); }
set { SetValue(ItemsSourceProperty, value); }
}
public ICommand ItemTappedCommand
{
get { return (ICommand)GetValue(ItemTappedCommandProperty); }
set { SetValue(ItemTappedCommandProperty, value); }
}
public ICommand ItemLongTappedCommand
{
get { return (ICommand)GetValue(ItemLongTappedCommandProperty);}
set { SetValue(ItemLongTappedCommandProperty, value); }
}
public DataTemplate ItemTemplate
{
get { return (DataTemplate)GetValue(ItemTemplateProperty); }
set { SetValue(ItemTemplateProperty, value); }
}
public int MaxColumns
{
get { return (int)GetValue(MaxColumnsProperty); }
set { SetValue(MaxColumnsProperty, value); }
}
public float TileHeight
{
get { return (float)GetValue(TileHeightProperty); }
set { SetValue(TileHeightProperty, value); }
}
private void BuildColumns()
{
ColumnDefinitions.Clear();
for (var i = 0; i < MaxColumns; i++)
{
ColumnDefinitions.Add(new ColumnDefinition { Width = new GridLength(1, GridUnitType.Star) });
}
}
private View BuildTile(object item1)
{
var template = ItemTemplate.CreateContent() as View;
template.BindingContext = item1;
if (ItemTappedCommand != null)
{
var tapGestureRecognizer = new TapGestureRecognizer
{
Command = ItemTappedCommand,
CommandParameter = item1,
};
template.GestureRecognizers.Add(tapGestureRecognizer);
}
// Tap komutu eziyor.
if (ItemLongTappedCommand != null)
{
template.Effects.Add(new LongPressedEffect());
LongPressedEffect.SetCommand(template, ItemLongTappedCommand);
//LongPressedEffect.SetCommandParameter(template, item1);
}
return template;
}
private void BuildTiles()
{
// Wipe out the previous row & Column definitions if they're there.
if (RowDefinitions.Any())
{
RowDefinitions.Clear();
}
BuildColumns();
Children.Clear();
var tiles = ItemsSource;
if (tiles != null)
{
var numberOfRows = Math.Ceiling(tiles.Count / (float)MaxColumns);
for (var i = 0; i < numberOfRows; i++)
{
RowDefinitions.Add(new RowDefinition { Height = new GridLength(0, GridUnitType.Auto) });
}
for (var index = 0; index < tiles.Count; index++)
{
var column = index % MaxColumns;
var row = (int)Math.Floor(index / (float)MaxColumns);
var tile = BuildTile(tiles[index]);
Children.Add(tile, column, row);
}
}
}
private void GridView_PropertyChanged(object sender, PropertyChangedEventArgs e)
{
if (e.PropertyName == ItemsSourceProperty.PropertyName)
{
var items = ItemsSource as INotifyCollectionChanged;
if (items != null)
items.CollectionChanged += ItemsCollectionChanged;
BuildTiles();
}
if (e.PropertyName == MaxColumnsProperty.PropertyName || e.PropertyName == TileHeightProperty.PropertyName)
{
BuildTiles();
}
}
private void GridView_PropertyChanging(object sender, Xamarin.Forms.PropertyChangingEventArgs e)
{
if (e.PropertyName == ItemsSourceProperty.PropertyName)
{
var items = ItemsSource as INotifyCollectionChanged;
if (items != null)
items.CollectionChanged -= ItemsCollectionChanged;
}
}
private void ItemsCollectionChanged(object sender, NotifyCollectionChangedEventArgs e)
{
BuildTiles();
}
}
public class LongPressedEffect : RoutingEffect
{
public LongPressedEffect() : base("MyApp.LongPressedEffect")
{
}
public static readonly BindableProperty CommandProperty = BindableProperty.CreateAttached("Command", typeof(ICommand), typeof(LongPressedEffect), (object)null);
public static ICommand GetCommand(BindableObject view)
{
//do something you want
Console.WriteLine("long press Gesture recognizer has been striked");
return (ICommand)view.GetValue(CommandProperty);
}
public static void SetCommand(BindableObject view, ICommand value)
{
view.SetValue(CommandProperty, value);
}
public static readonly BindableProperty CommandParameterProperty = BindableProperty.CreateAttached("CommandParameter", typeof(object), typeof(LongPressedEffect), (object)null);
public static object GetCommandParameter(BindableObject view)
{
return view.GetValue(CommandParameterProperty);
}
public static void SetCommandParameter(BindableObject view, object value)
{
view.SetValue(CommandParameterProperty, value);
}
}
答案 0 :(得分：0)
我注意到您使用Effect来创建自己的长按命令。但是，如果您同时消耗TapGestureRecognizer，它将截获效果。这样您长按的命令就不会被触发。
您可以定义效果中的单击事件，以实现二者。这是我的效果：
public class PressedEffect : RoutingEffect
{
public PressedEffect() : base("MyApp.PressedEffect")
{
}
public static readonly BindableProperty LongTapCommandProperty = BindableProperty.CreateAttached("LongTapCommand", typeof(ICommand), typeof(PressedEffect), (object)null);
public static ICommand GetLongTapCommand(BindableObject view)
{
return (ICommand)view.GetValue(LongTapCommandProperty);
}
public static void SetLongTapCommand(BindableObject view, ICommand value)
{
view.SetValue(LongTapCommandProperty, value);
}
public static readonly BindableProperty LongParameterProperty = BindableProperty.CreateAttached("LongParameter", typeof(object), typeof(PressedEffect), (object)null);
public static object GetLongParameter(BindableObject view)
{
return view.GetValue(LongParameterProperty);
}
public static void SetLongParameter(BindableObject view, object value)
{
view.SetValue(LongParameterProperty, value);
}
public static readonly BindableProperty TapCommandProperty = BindableProperty.CreateAttached("TapCommand", typeof(ICommand), typeof(PressedEffect), (object)null);
public static ICommand GetTapCommand(BindableObject view)
{
return (ICommand)view.GetValue(TapCommandProperty);
}
public static void SetTapCommand(BindableObject view, ICommand value)
{
view.SetValue(TapCommandProperty, value);
}
public static readonly BindableProperty TapParameterProperty = BindableProperty.CreateAttached("TapParameter", typeof(object), typeof(PressedEffect), (object)null);
public static object GetTapParameter(BindableObject view)
{
return view.GetValue(TapParameterProperty);
}
public static void SetTapParameter(BindableObject view, object value)
{
view.SetValue(TapParameterProperty, value);
}
}
Android实现：
[assembly: ResolutionGroupName("MyApp")]
[assembly: ExportEffect(typeof(AndroidPressedEffect), "PressedEffect")]
namespace PressedEffectDemo.Droid
{
public class AndroidPressedEffect : PlatformEffect
{
private bool _attached;
public static void Initialize() { }
public AndroidPressedEffect()
{
}
protected override void OnAttached()
{
if (!_attached)
{
if (Control != null)
{
Control.LongClickable = true;
Control.LongClick += Control_LongClick;
Control.Click += Control_Click;
}
else
{
Container.LongClickable = true;
Container.LongClick += Control_LongClick;
Container.Click += Control_Click;
}
_attached = true;
}
}
private void Control_Click(object sender, EventArgs e)
{
var command = PressedEffect.GetTapCommand(Element);
command?.Execute(PressedEffect.GetTapParameter(Element));
}
private void Control_LongClick(object sender, Android.Views.View.LongClickEventArgs e)
{
var command = PressedEffect.GetLongTapCommand(Element);
command?.Execute(PressedEffect.GetLongParameter(Element));
}
protected override void OnDetached()
{
if (_attached)
{
if (Control != null)
{
Control.LongClickable = true;
Control.LongClick -= Control_LongClick;
Control.Click -= Control_Click;
}
else
{
Container.LongClickable = true;
Container.LongClick -= Control_LongClick;
Control.Click -= Control_Click;
}
_attached = false;
}
}
}
}
iOS实现：
[assembly: ResolutionGroupName("MyApp")]
[assembly: ExportEffect(typeof(iOSPressedEffect), "PressedEffect")]
namespace PressedEffectDemo.iOS
{
public class iOSPressedEffect : PlatformEffect
{
private bool _attached;
private readonly UILongPressGestureRecognizer _longPressRecognizer;
private readonly UITapGestureRecognizer _tapRecognizer;
public iOSPressedEffect()
{
_longPressRecognizer = new UILongPressGestureRecognizer(HandleLongClick);
_tapRecognizer = new UITapGestureRecognizer(HandleClick);
}
protected override void OnAttached()
{
if (!_attached)
{
Container.AddGestureRecognizer(_longPressRecognizer);
Container.AddGestureRecognizer(_tapRecognizer);
_attached = true;
}
}
private void HandleClick()
{
var command = PressedEffect.GetTapCommand(Element);
command?.Execute(PressedEffect.GetTapParameter(Element));
}
private void HandleLongClick(UILongPressGestureRecognizer recognizer)
{
if (recognizer.State == UIGestureRecognizerState.Ended)
{
var command = PressedEffect.GetLongTapCommand(Element);
command?.Execute(PressedEffect.GetLongParameter(Element));
}
}
protected override void OnDetached()
{
if (_attached)
{
Container.RemoveGestureRecognizer(_longPressRecognizer);
Container.RemoveGestureRecognizer(_tapRecognizer);
_attached = false;
}
}
}
}
最后，您可以像这样在XAML上使用它们：
<StackLayout>
<Grid HeightRequest="200"
BackgroundColor="Green"
local:PressedEffect.TapCommand="{Binding TapCommand}"
local:PressedEffect.LongTapCommand="{Binding LongTapCommand}">
<Grid.Effects>
<local:PressedEffect />
</Grid.Effects>
</Grid>
</StackLayout>
您可以参考我的示例here。