Answers

• Bushbert Member ✭✭✭

  September 2018

  Same principle in IOS. You can use this to generate the bitmap from a UIView.

  public static UIImage AsImage(this UIView view)
  
          {
  
              UIGraphics.BeginImageContextWithOptions(view.Bounds.Size, true, 0);
  
              view.Layer.RenderInContext(UIGraphics.GetCurrentContext());
  
              var img = UIGraphics.GetImageFromCurrentImageContext();
  
              UIGraphics.EndImageContext();
  
              return img;
  
          }
  

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• LeoOsvald Member ✭✭

  September 2018

  what view should i pass as parameter? In the android solution, i use the ViewGroup.GetChildAt(desiredindex) so it draws the view i want

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• LandLu Member, Xamarin Team Xamurai

  September 2018

  Why not use a ContentView and create a custom renderer for it?
  Create a custom contentView and place Forms controls there:

  public partial class CustomView : ContentView
  {
      public CustomView ()
      {
          InitializeComponent ();
      }
  }
  

  And the custom renderer for it:

  [assembly: ExportRenderer(typeof(CustomView), typeof(CustomViewRendererForiOS))]
  namespace Demo.iOS
  {
      public class CustomViewRendererForiOS : ViewRenderer
      {
  
      }
  }
  

  At last you can use this contentView in the page.

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• LeoOsvald Member ✭✭

  September 2018

  Im using a render, LandLu, but as i need to convert a xamarin.form.view to a UIView, nothing seems to work as I wish.

  In android im using this:

  private void NewElement_OnDrawBitmap(object sender, EventArgs e)
       {
  
  
          if (ViewGroup != null)
          {
              //gets the desired stack layout
              Android.Views.View subView = ViewGroup.GetChildAt(0);
              int width = subView.Width;
              int height = subView.Height;
              //draws the bitmap
              Bitmap b = Bitmap.CreateBitmap(width, height, Bitmap.Config.Argb8888);
              Canvas c = new Canvas(b);
              ViewGroup.Draw(c);
  
              //save the file
              SaveBitmapToFile(b);
          }
      }
  

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• LandLu Member, Xamarin Team Xamurai

  September 2018

  @LeoOsvald ContentView is rendered as UIView on iOS. You can create your custom content view, put your controls there.
  Then the renderer itself is a UIView object.

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• LeoOsvald Member ✭✭

  September 2018 edited September 2018 Accepted Answer

  Found the solution :

  private void NewElement_OnDrawBitmap(object sender, EventArgs e)
  {
  var formsView = Element;
  var rect = new CGRect(0, 0, 400, 400);
  var iOSView = FormsViewToNativeiOS.ConvertFormsToNative(formsView, rect);
  UiImage = ConvertViewToImage(iOSView);
  SaveImage(UiImage);
  }

  public static UIView ConvertFormsToNative(Xamarin.Forms.View view, CGRect size)
  {
  var renderer = Platform.CreateRenderer(view);

          renderer.NativeView.Frame = size;
  
          renderer.NativeView.AutoresizingMask = UIViewAutoresizing.All;
          renderer.NativeView.ContentMode = UIViewContentMode.ScaleToFill;
  
          renderer.Element.Layout(size.ToRectangle());
  
          var nativeView = renderer.NativeView;
  
          nativeView.SetNeedsLayout();
  
          return nativeView;
      }
  

  void SaveImage(UIImage image)
  {
  var sdCardPath = Environment.GetFolderPath(Environment.SpecialFolder.MyPictures);
  string pngFilename = System.IO.Path.Combine(sdCardPath, Element.Nome + DateTime.Now.ToString("dd-MM-yyyy_hh:mm:ss:tt") + ".png");
  NSData imgData = image.AsPNG();
  if (imgData.Save(pngFilename, false, out NSError err))
  {
  Debug.WriteLine("saved as " + pngFilename);
  }
  else
  {
  Debug.WriteLine("NOT saved as " + pngFilename + " because" + err.LocalizedDescription);
  }
  }

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• colinedwards USMember ✭✭

  April 2019

  var renderer1 = RendererFactory.GetRenderer(view); <= deprecated
  var renderer2 = Platform.CreateRenderer(view); <= deprecated
  var renderer3 = Platform.CreateRendererWithContext(view, context); <= current

  it would be nice if people made their minds up...

  see Michael Ridland October 2015

  I'm interested to see where the 'context' comes from...

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• colinedwards USMember ✭✭

  April 2019

  updated with obsolescence removed...

  public class NativeButtonRenderer : ButtonRenderer
  {
  public NativeButtonRenderer(Context context) : base(context)
  {
  }

      protected override void OnElementChanged(ElementChangedEventArgs<Xamarin.Forms.Button> e)
      {
          base.OnElementChanged(e);
  
          if (e.NewElement != null)
          {
              this.Control.Click += Control_Click;
          }
      }
  
      void Control_Click(object sender, EventArgs e)
      {
          var formsView = new CommonFormsView();
  
          var nativeConverted = FormsToNativeDroid.ConvertFormsToNative(formsView, Context, new Rectangle(0, 0, 400, 400));
  
          var builder = new AlertDialog.Builder(Context);
  
          builder.SetView(nativeConverted);
  
          builder.SetTitle("Forms View");
  
          var dialog = builder.Create();
          dialog.Show();
      }
  }
  
  public class FormsToNativeDroid
  {
      public static Android.Views.View ConvertFormsToNative(Xamarin.Forms.View view, Android.Content.Context context, Rectangle size)
      {
          var renderer = Platform.CreateRendererWithContext(view, context);
  
          var viewGroup = renderer.View;
  
          renderer.Tracker.UpdateLayout();
  
          var layoutParams = new ViewGroup.LayoutParams((int)size.Width, (int)size.Height);
          viewGroup.LayoutParameters = layoutParams;
          view.Layout(size);
          viewGroup.Layout(0, 0, (int)view.WidthRequest, (int)view.HeightRequest);
  
          return viewGroup;
      }
  }
  

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