CODEWITHSUNDEEP
xamarin.formstouch
Alex Zaitsev
Alex Zaitsev

Reputation: 2766

How to trigger touch start (not when the finger released) in the xamarin forms?

The problem is that TapGestureRecognizer triggers only when I release my finger, but I want to trigger when I just started the touch

Here is the way how I use it at the moment:

<Image.GestureRecognizers>
    <TapGestureRecognizer
         Tapped="TapGestureRecognizer_Tapped"
         NumberOfTapsRequired="1" />
</Image.GestureRecognizers>

Upvotes: 1

Views: 294

Answers (1)

Liyun Zhang - MSFT
Liyun Zhang - MSFT

Reputation: 14244

You can try to use a custom render to do something you want when the user touches the image.

  1. Declare the custom image in the share project:

    public class MyImage : Image
{
}

  2. In the android part:

    [assembly: ExportRenderer(typeof(MyImage), typeof(MyImageRenderer))]
namespace AppTest.Droid
{

    public class MyImageRenderer : ImageRenderer
    {
        public MyImageRenderer(Context context) : base(context) { }
        public override bool OnTouchEvent(MotionEvent e)
        {
            if(e.Action == MotionEventActions.Down)
            {
                //do something
            }

            return base.OnTouchEvent(e);

        }
    }
}

  3. In the ios part:

    [assembly: ExportRenderer(typeof(MyImage), typeof(MyImageRenderer))]
namespace AppTest.iOS
{
    public class MyImageRenderer : ImageRenderer
    {
        protected override void OnElementChanged(ElementChangedEventArgs<Image> e)
        {
            base.OnElementChanged(e);
            if (Control != null)
            {
                Control.UserInteractionEnabled = true;
            }
        }
        public override void TouchesBegan(NSSet touches, UIEvent evt)
        {
            //do something
            base.TouchesBegan(touches, evt);
        }

    }
}

  4. Use it in the xaml:

    <ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
     xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
     xmlns:local="clr-namespace:AppTest"
     x:Class="AppTest.MainPage">
    <StackLayout>
      <local:MyImage Source="your image" BackgroundColor="Blue"/>
    </StackLayout>

</ContentPage>

Upvotes: 1

Related Questions