I create custom ScrollView.
This is done so that the swipes and scrolls work.
I need to make a vertical scroll.
Help me please
`
public class GestureScrollView : ScrollView
{
public event EventHandler SwipeDown;
public event EventHandler SwipeTop;
public event EventHandler SwipeLeft;
public event EventHandler SwipeRight;
public void OnSwipeDown() =>
SwipeDown?.Invoke(this, null);
public void OnSwipeTop() =>
SwipeTop?.Invoke(this, null);
public void OnSwipeLeft()
{
SwipeLeft?.Invoke(this, null);
}
public void OnSwipeRight()
{
SwipeRight?.Invoke(this, null);
}
}`
Android
`[assembly: ExportRenderer(typeof(GestureScrollView), typeof(Swipe.Droid.Platform.Renderers.GestureScrollViewRenderer))]
namespace Swipe.Droid.Platform.Renderers
{
public class GestureScrollViewRenderer : ScrollViewRenderer
{
readonly CustomGestureListener _listener;
readonly GestureDetector _detector;
public GestureScrollViewRenderer(Context context) : base(context)
{
_listener = new CustomGestureListener();
_detector = new GestureDetector(context, _listener);
}
public override bool DispatchTouchEvent(MotionEvent e)
{
if (_detector != null)
{
_detector.OnTouchEvent(e);
base.DispatchTouchEvent(e);
return true;
}
return base.DispatchTouchEvent(e);
}
public override bool OnTouchEvent(MotionEvent ev)
{
base.OnTouchEvent(ev);
if (_detector != null)
return _detector.OnTouchEvent(ev);
return false;
}
protected override void OnElementChanged(VisualElementChangedEventArgs e)
{
base.OnElementChanged(e);
if (e.NewElement == null)
{
this.GenericMotion -= HandleGenericMotion;
this.Touch -= HandleTouch;
_listener.OnSwipeLeft -= HandleOnSwipeLeft;
_listener.OnSwipeRight -= HandleOnSwipeRight;
_listener.OnSwipeTop -= HandleOnSwipeTop;
_listener.OnSwipeDown -= HandleOnSwipeDown;
}
if (e.OldElement == null)
{
this.GenericMotion += HandleGenericMotion;
this.Touch += HandleTouch;
_listener.OnSwipeLeft += HandleOnSwipeLeft;
_listener.OnSwipeRight += HandleOnSwipeRight;
_listener.OnSwipeTop += HandleOnSwipeTop;
_listener.OnSwipeDown += HandleOnSwipeDown;
}
}
void HandleTouch(object sender, TouchEventArgs e)
{
_detector.OnTouchEvent(e.Event);
}
void HandleGenericMotion(object sender, GenericMotionEventArgs e)
{
_detector.OnTouchEvent(e.Event);
}
void HandleOnSwipeLeft(object sender, EventArgs e)
{
var _gi = (GestureScrollView)this.Element;
_gi.OnSwipeLeft();
}
void HandleOnSwipeRight(object sender, EventArgs e)
{
var _gi = (GestureScrollView)this.Element;
_gi.OnSwipeRight();
}
void HandleOnSwipeTop(object sender, EventArgs e)
{
var _gi = (GestureScrollView)this.Element;
_gi.OnSwipeTop();
}
void HandleOnSwipeDown(object sender, EventArgs e)
{
var _gi = (GestureScrollView)Element;
_gi.OnSwipeDown();
}
}
public class CustomGestureListener : GestureDetector.SimpleOnGestureListener
{
private static int SWIPE_THRESHOLD = 100;
static readonly int SWIPE_VELOCITY_THRESHOLD = 100;
MotionEvent mLastOnDownEvent;
public event EventHandler OnSwipeDown;
public event EventHandler OnSwipeTop;
public event EventHandler OnSwipeLeft;
public event EventHandler OnSwipeRight;
public override bool OnScroll(MotionEvent e1, MotionEvent e2, float distanceX, float distanceY)
{
return base.OnScroll(e1, e2, distanceX, distanceY);
}
public override bool OnDown(MotionEvent e)
{
mLastOnDownEvent = e;
return true;
}
public override bool OnFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY)
{
Console.WriteLine("OnFling");
if (e1 == null)
e1 = mLastOnDownEvent;
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)
OnSwipeRight?.Invoke(this, null);
else
OnSwipeLeft?.Invoke(this, null);
}
}
else if (Math.Abs(diffY) > SWIPE_THRESHOLD && Math.Abs(velocityY) > SWIPE_VELOCITY_THRESHOLD)
{
if (diffY > 0)
OnSwipeDown?.Invoke(this, null);
else
OnSwipeTop?.Invoke(this, null);
}
return base.OnFling(e1, e2, velocityX, velocityY);
}
}
}`
Xaml:
<ctrl:GestureScrollView x:Name="gi"> ... </ctrl:GestureScrollView>
C#:
`gi.SwipeDown += (s, e) =>
{
DisplayAlert("Gesture Info", "Swipe Down Detected", "OK");
// scroll down
};
gi.SwipeTop += (s, e) =>
{
DisplayAlert("Gesture Info", "Swipe Top Detected", "OK");
// scroll top
};
gi.SwipeLeft += (s, e) =>
{
DisplayAlert("Gesture Info", "Swipe Left Detected", "OK");
((NewsFeedDetailPageModel)BindingContext).OpenSourceCommand.Execute(null);
};
gi.SwipeRight += (s, e) =>
{
DisplayAlert("Gesture Info", "Swipe Right Detected", "OK");
((NewsFeedDetailPageModel)BindingContext).BackCommand.Execute(null);
};`
\Program Files\Microsoft Visual Studio\2017\Enterprise\MSBuild\Xamarin\Android\Xamarin.Android.Common.targets 1577
