c# - OnGestureListener 在 Xamarin.Android 上的 fragment 中的 ListView 上捕获

Question

我在 Activity 上创建了一个手势 Listener，效果很好:

[Activity (Theme = "@android:style/Theme.Holo.Light", Label = "@string/app_name", MainLauncher = true, Icon = "@drawable/ic_launcher", ConfigurationChanges=Android.Content.PM.ConfigChanges.Orientation | Android.Content.PM.ConfigChanges.ScreenSize)]
public class MainActivity : Activity, GestureDetector.IOnGestureListener
{

    private GestureDetector _gestureDetector;

    public bool OnDown(MotionEvent e)
    {
        return false;
    }
    public bool OnFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY)
    {
        bool result = false;
        int SWIPE_THRESHOLD = 80;
        int SWIPE_VELOCITY_THRESHOLD = 80;
        try
        {
            float diffY = e2.GetY() - e1.GetY();
            float diffX = e2.GetX() - e1.GetX();
            if (Math.Abs(diffX) > Math.Abs(diffY))
            {
                if (Math.Abs(diffX) > SWIPE_THRESHOLD && Math.Abs(velocityX) > SWIPE_VELOCITY_THRESHOLD)
                {
                    if (diffX > 0)
                    {
                        //code for swipe right here (this would is different for each ImageView)
                        previousImage();
                    }
                    else
                    {
                        //code for swipe Left here (this would is different for each ImageView)
                        nextImage();
                    }
                }
            }
        }
        catch (Exception exception)
        {
            //exception.printStackTrace();
        }
        return result;
    }
    public void OnLongPress(MotionEvent e) {}
    public bool OnScroll(MotionEvent e1, MotionEvent e2, float distanceX, float distanceY)
    {
        return false;
    }
    public void OnShowPress(MotionEvent e) {}
    public bool OnSingleTapUp(MotionEvent e)
    {
        return false;
    }


    public override bool OnTouchEvent(MotionEvent e)
    {
        _gestureDetector.OnTouchEvent(e);
        return false;
    }

    protected override void OnCreate (Bundle bundle)
    {
        base.OnCreate (bundle);

        // Set our view from the "main" layout resource
        SetContentView (Resource.Layout.Main);

        _gestureDetector = new GestureDetector(this);

    }

但是当我尝试在 Fragment 上执行相同操作时，我发现没有要Override 的OnTouchEvent >。同样在 Activity 中，gestureListener 正在监听整个屏幕，现在我希望它出现在 ImageView 上。我该怎么做？

通过 Google 搜索，我发现我需要转换这个答案 Detect swipe gesture in fragment到 C#，但我无法做到这一点。

Answer 1

试试这个:

public class YourFragment : Fragment, View.IOnTouchListener, GestureDetector.IOnGestureListener
{
    private GestureDetector _gestureDetector;
    private ImageView imageView;
    public YourFragment()
    {
        this.RetainInstance = true;
    }
    public override View OnCreateView(LayoutInflater inflater, ViewGroup container, Android.OS.Bundle savedInstanceState)
    {
        var ignored = base.OnCreateView(inflater, container, savedInstanceState);
        var view = inflater.Inflate(Resource.Layout.fragment_profile, null);
         imageView = view.FindViewById<ImageView>(Resource.Id.profile_image);
        _gestureDetector = new GestureDetector(this);
        imageView.SetOnTouchListener(this);
        return view;
    }

    public bool OnTouch(View v, MotionEvent e)
    {
        return _gestureDetector.OnTouchEvent(e);
    }

    public bool OnDown(MotionEvent e)
    {
        //rzee: Changed to true
        return true;
    }

    public bool OnFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY)
    {
        throw new System.NotImplementedException();
    }

    public void OnLongPress(MotionEvent e)
    {

    }

    public bool OnScroll(MotionEvent e1, MotionEvent e2, float distanceX, float distanceY)
    {
        //rzee: Changed to true
        return true;
    }

    public void OnShowPress(MotionEvent e)
    {
    }

    public bool OnSingleTapUp(MotionEvent e)
    {
        return true;
    }
}

我已经测试了我这边，工作得很好。

干杯!