f-miyu score 1499
2019/05/28 01:26 投稿
| 問題は、Androidでは、`Appearing`が呼ばれるタイミングが早すぎるところにあります。 |
| なので、`Task.Delay`で少々待ってやるというのが、手っ取り早い解決策です。 |
| ```c# |
| private async void SetFocus(object sender, EventArgs e) |
| { |
| await Task.Delay(100); |
| var f = (Binding)FocusControl; |
| var s = f.Source as Entry; |
| s.Focus(); |
| } |
| ``` |
| --- |
| ちょっと本格的に、画面が表示されるタイミングでフォーカスを当てる様なエフェクトを作ってみました。 |
| Androidプロジェクト |
| ```C# |
| [assembly: ResolutionGroupName("BlankApp1")] |
| [assembly: ExportEffect(typeof(FocusEffect), nameof(FocusEffect))] |
| namespace BlankApp1.Droid |
| { |
| public class FocusEffect : PlatformEffect |
| { |
| private Listener _listener; |
| protected override void OnAttached() |
| { |
| _listener = new Listener(this); |
| Control.ViewTreeObserver.AddOnPreDrawListener(_listener); |
| } |
| protected override void OnDetached() |
| { |
| if (_listener != null) |
| { |
| Control.ViewTreeObserver.RemoveOnPreDrawListener(_listener); |
| _listener = null; |
| } |
| } |
| private void Focus() |
| { |
| (Element as VisualElement)?.Focus(); |
| if (_listener != null) |
| { |
| Control.ViewTreeObserver.RemoveOnPreDrawListener(_listener); |
| _listener = null; |
| } |
| } |
| private class Listener : Java.Lang.Object, ViewTreeObserver.IOnPreDrawListener |
| { |
| private FocusEffect _effect; |
| public Listener(FocusEffect effect) |
| { |
| _effect = effect; |
| } |
| public bool OnPreDraw() |
| { |
| _effect.Focus(); |
| return true; |
| } |
| } |
| } |
| } |
| ``` |
| 共通プロジェクト |
| ```C# |
| namespace BlankApp1.Effects |
| { |
| public class FocusEffect : RoutingEffect |
| { |
| public FocusEffect() : base($"BlankApp1.{nameof(FocusEffect)}") |
| { |
| } |
| } |
| } |
| ``` |
| ```xml |
| <?xml version="1.0" encoding="utf-8" ?> |
| <ContentPage |
| x:Class="BlankApp1.Views.LoginPage" |
| xmlns="http://xamarin.com/schemas/2014/forms" |
| xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml" |
| xmlns:b="clr-namespace:BlankApp1.Behavior" |
| xmlns:e="clr-namespace:BlankApp1.Effects" |
| xmlns:prism="clr-namespace:Prism.Mvvm;assembly=Prism.Forms" |
| prism:ViewModelLocator.AutowireViewModel="True"> |
| <StackLayout Style="{StaticResource StackLayoutStyle}"> |
| <Entry x:Name="User" > |
| <Entry.Effects> |
| <e:FocusEffect /> |
| </Entry.Effects> |
| </Entry> |
| </StackLayout> |
| </ContentPage> |
| ``` |
