iot/projects/Demo/Demo.Android/Controls/CameraPreviewRenderer.cs

using Android.Content;
using Android.Hardware;
using Demo.Droid.Controls;
using Xamarin.Forms;
using Xamarin.Forms.Platform.Android;

[assembly: ExportRenderer(typeof(Demo.Controls.CameraPreview), typeof(CameraPreviewRenderer))]

namespace Demo.Droid.Controls
{
    public class CameraPreviewRenderer : ViewRenderer<Demo.Controls.CameraPreview, Demo.Droid.Controls.CameraPreview>
    {
        private CameraPreview cameraPreview;

        public CameraPreviewRenderer(Context context) : base(context)
        {
        }

        protected override void OnElementChanged(ElementChangedEventArgs<Demo.Controls.CameraPreview> e)
        {
            base.OnElementChanged(e);
            if (e.NewElement != null)
            {
                if (Control == null)
                {
                    cameraPreview = new CameraPreview(Context);
                    SetNativeControl(cameraPreview);
                }
                var camera = Camera.Open((int)e.NewElement.Camera);
                var parameters = camera.GetParameters();
                var width = parameters.PreviewSize.Width;
                var height = parameters.PreviewSize.Height;
                var format = parameters.PreviewFormat;
                camera.SetPreviewCallback(new PreviewCallback(width, height, format));
                Control.Preview = camera;
            }
        }

        protected override void Dispose(bool disposing)
        {
            if (disposing)
            {
                Control.Preview.Release();
            }
            base.Dispose(disposing);
        }
    }
}