How to construct custom views in xamarin

Question

Is there any tutorial which will enable me to design custom views in xamarin?I want to build pinch zoom functionality for my android app using xamarin.

I have tried following code,but its not working,I am always getting android.view.InflateException: Binary XML file line #1: Error inflating class LA_Application.ZoomView error

using System;    
using System.Collections.Generic;
using System.Linq;    
using System.Text;    
using Android.App;    
using Android.Content;    
using Android.OS;    
using Android.Runtime;    
using Android.Util;    
using Android.Views;    
using Android.Widget;    
using Android.Graphics;

namespace LA_Application    
{

    public class ZoomView : FrameLayout      
    {

        private ScaleGestureDetector mScaleDetector;    
        private static float mScaleFactor = 1.0f;   


        public ZoomView (Context context) : base (context)
        {
            Initialize ();    
        }

        public ZoomView (Context context, IAttributeSet attrs) : base (context,attrs)    
        {
            Initialize ();    
        }

        public ZoomView (Context context, IAttributeSet attrs, int defStyle) : base (context, attrs, defStyle)
        {
            Initialize ();
        }

        void Initialize ()
        {
            mScaleDetector = new ScaleGestureDetector(Context, new ScaleListener());
        }

        public override bool OnTouchEvent (MotionEvent e)
        {
            mScaleDetector.OnTouchEvent(e);

            return true;
        }

        protected override void OnDraw(Android.Graphics.Canvas canvas)
        {
            base.OnDraw(canvas);

            canvas.Save();    
            canvas.Scale(mScaleFactor, mScaleFactor);
            canvas.Restore();
        }
    }

    private class ScaleListener : ScaleGestureDetector.SimpleOnScaleGestureListener
    {
        public override bool OnScale(ScaleGestureDetector detector)
        {
            mScaleFactor *= detector.ScaleFactor;

            // Don't let the object get too small or too large.
            mScaleFactor = Math.Max(0.1f, Math.Min(mScaleFactor, 5.0f));

            return true;
        }  
    }
}

}

and in layout file

<?xml version="1.0" encoding="utf-8"?>
<LA_Application.ZoomView xmlns:android="http://schemas.android.com/apk/res/android"
                         android:layout_width="match_parent"
                         android:layout_height="match_parent"
                         android:id="@+id/my_view" />

activity code

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

    SetContentView(Resource.Layout.zoomview);

    /*some code*/
}

Solution 1

I would suggest checking out this Java Android tutorial to get an idea of what you need to setup:

http://developer.android.com/training/custom-views/index.html

You may need to create an attributes xml file for your custom view.

Another approach you may want to consider is to use a fragment instead of a view:

http://docs.xamarin.com/guides/android/platform_features/fragments/fragments_walkthrough

Solution 2

In the layout file you need to write the path to your class in small letters. For me Core.Droid.MyImageView had to be written as core.droid.MyImageView.

I am not sure if only the first letter or all letter have to be written in small, but you can try either lA_Application.ZoomView or la_application.ZoomView. One of them will very likely work :)

Solution 3

Here is the skeleton of how to create a custom view in xamarin.android

http://xandroid4net.blogspot.com/2014/09/custom-view.html

Then take Emmanuel Touzery answer and add it to the skeleton

android pinch zoom