Drawing view - draw - save - load #2088

nk-alex · 2024-08-02T08:10:41Z

nk-alex
Aug 2, 2024

I would like persistently save the state of my drawing view. I know I can get the Stream from the drawn lines, but I'm wondering if I could save this stream into a file (byte array format) and later on, read this file, and load the drawing view with the content.

I haven't been able to find a way to go from the Stream back to ObservableCollection<IDrawingLine>

VladislavAntonyuk · 2024-08-02T09:09:04Z

VladislavAntonyuk
Aug 2, 2024
Maintainer

you can just serialize and deserialize the collection of points. You don't need to use stream in this case

3 replies

nk-alex Aug 2, 2024
Author

@VladislavAntonyuk Thanks for the response. I'm trying the way you suggested:

View:

<toolkit:DrawingView 
			 DrawingLineStarted="Signature_DrawingLineStarted"
			 ShouldClearOnFinish="False" 
			 IsMultiLineModeEnabled="True" 
			 BackgroundColor="Transparent"
			 Lines="{Binding Signature, Mode=OneWayToSource}" />

ViewModel:

private ObservableCollection<DrawingLine> signature;
public ObservableCollection<DrawingLine> Signature
{
	get { return signature; }
	set { SetProperty(ref signature, value); }
}

Save signature:
string json = JsonConvert.SerializeObject(Signature, Formatting.Indented);

Load signature:
Signature = JsonConvert.DeserializeObject<ObservableCollection<DrawingLine>>(json);

But in order for this to work as I expect, I need to set the DrawingView Lines Binding to Mode=TwoWay. Whenever I do that, I'm getting this error:

[mono-rt] [ERROR] FATAL UNHANDLED EXCEPTION: System.NullReferenceException: Object reference not set to an instance of an object.
[mono-rt]    at CommunityToolkit.Maui.Core.Handlers.DrawingViewHandler.ConnectHandler(MauiDrawingView platformView)
[mono-rt]    at Microsoft.Maui.Handlers.ViewHandler`2[[CommunityToolkit.Maui.Core.IDrawingView, CommunityToolkit.Maui.Core, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null],[CommunityToolkit.Maui.Core.Views.MauiDrawingView, CommunityToolkit.Maui.Core, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null]].OnConnectHandler(View platformView) in /_/src/Core/src/Handlers/View/ViewHandlerOfT.cs:line 76
[mono-rt]    at Microsoft.Maui.Handlers.ViewHandler.OnConnectHandler(Object platformView) in /_/src/Core/src/Handlers/View/ViewHandler.cs:line 204
[mono-rt]    at Microsoft.Maui.Handlers.ElementHandler.ConnectHandler(Object platformView) in /_/src/Core/src/Handlers/Element/ElementHandler.cs:line 106
[mono-rt]    at Microsoft.Maui.Handlers.ElementHandler.SetVirtualView(IElement view) in /_/src/Core/src/Handlers/Element/ElementHandler.cs:line 64
[mono-rt]    at Microsoft.Maui.Handlers.ViewHandler`2[[CommunityToolkit.Maui.Core.IDrawingView, CommunityToolkit.Maui.Core, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null],[CommunityToolkit.Maui.Core.Views.MauiDrawingView, CommunityToolkit.Maui.Core, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null]].SetVirtualView(IView view) in /_/src/Core/src/Handlers/View/ViewHandlerOfT.cs:line 53
[mono-rt]    at Microsoft.Maui.Handlers.ViewHandler`2[[CommunityToolkit.Maui.Core.IDrawingView, CommunityToolkit.Maui.Core, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null],[CommunityToolkit.Maui.Core.Views.MauiDrawingView, CommunityToolkit.Maui.Core, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null]].SetVirtualView(IElement view) in /_/src/Core/src/Handlers/View/ViewHandlerOfT.cs:line 56
[mono-rt]    at Microsoft.Maui.Controls.Element.SetHandler(IElementHandler newHandler) in /_/src/Controls/src/Core/Element/Element.cs:line 987
[mono-rt]    at Microsoft.Maui.Controls.Element.set_Handler(IElementHandler value) in /_/src/Controls/src/Core/Element/Element.cs:line 929
[mono-rt]    at Microsoft.Maui.Controls.VisualElement.Microsoft.Maui.IElement.set_Handler(IElementHandler value) in /_/src/Controls/src/Core/VisualElement/VisualElement.cs:line 2074
[mono-rt]    at Microsoft.Maui.Platform.ElementExtensions.ToHandler(IElement view, IMauiContext context) in /_/src/Core/src/Platform/ElementExtensions.cs:line 96
[mono-rt]    at Microsoft.Maui.Platform.ElementExtensions.ToPlatform(IElement view, IMauiContext context) in /_/src/Core/src/Platform/ElementExtensions.cs:line 127
[mono-rt]    at Microsoft.Maui.Handlers.BorderHandler.UpdateContent(IBorderHandler handler) in /_/src/Core/src/Handlers/Border/BorderHandler.Android.cs:line 45
[mono-rt]    at Microsoft.Maui.Handlers.BorderHandler.MapContent(IBorderHandler handler, IBorderView border) in /_/src/Core/src/Handlers/Border/BorderHandler.cs:line 163
[mono-rt]    at Microsoft.Maui.PropertyMapper`2.<>c__DisplayClass5_0[[Microsoft.Maui.IBorderView, Microsoft.Maui, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null],[Microsoft.Maui.Handlers.IBorderHandler, Microsoft.Maui, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null]].<Add>b__0(IElementHandler h, IElement v) in /_/src/Core/src/PropertyMapper.cs:line 172
[mono-rt]    at Microsoft.Maui.PropertyMapper.UpdatePropertyCore(String key, IElementHandler viewHandler, IElement virtualView) in /_/src/Core/src/PropertyMapper.cs:line 47
[mono-rt]    at Microsoft.Maui.PropertyMapper.UpdateProperties(IElementHandler viewHandler, IElement virtualView) in /_/src/Core/src/PropertyMapper.cs:line 82
[mono-rt]    at Microsoft.Maui.Handlers.ElementHandler.SetVirtualView(IElement view) in /_/src/Core/src/Handlers/Element/ElementHandler.cs:line 79
[mono-rt]    at Microsoft.Maui.Handlers.ViewHandler`2[[Microsoft.Maui.IBorderView, Microsoft.Maui, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null],[Microsoft.Maui.Platform.ContentViewGroup, Microsoft.Maui, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null]].SetVirtualView(IView view) in /_/src/Core/src/Handlers/View/ViewHandlerOfT.cs:line 53
[mono-rt]    at Microsoft.Maui.Handlers.BorderHandler.SetVirtualView(IView view) in /_/src/Core/src/Handlers/Border/BorderHandler.Android.cs:line 28
[mono-rt]    at Microsoft.Maui.Handlers.ViewHandler`2[[Microsoft.Maui.IBorderView, Microsoft.Maui, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null],[Microsoft.Maui.Platform.ContentViewGroup, Microsoft.Maui, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null]].SetVirtualView(IElement view) in /_/src/Core/src/Handlers/View/ViewHandlerOfT.cs:line 56
[mono-rt]    at Microsoft.Maui.Controls.Element.SetHandler(IElementHandler newHandler) in /_/src/Controls/src/Core/Element/Element.cs:line 987
[mono-rt]    at Microsoft.Maui.Controls.Element.set_Handler(IElementHandler value) in /_/src/Controls/src/Core/Element/Element.cs:line 929
[mono-rt]    at Microsoft.Maui.Controls.VisualElement.Microsoft.Maui.IElement.set_Handler(IElementHandler value) in /_/src/Controls/src/Core/VisualElement/VisualElement.cs:line 2074
[mono-rt]    at Microsoft.Maui.Platform.ElementExtensions.ToHandler(IElement view, IMauiContext context) in /_/src/Core/src/Platform/ElementExtensions.cs:line 96
[mono-rt]    at Microsoft.Maui.Platform.ElementExtensions.ToPlatform(IElement view, IMauiContext context) in /_/src/Core/src/Platform/ElementExtensions.cs:line 127
[mono-rt]    at Microsoft.Maui.Handlers.LayoutHandler.SetVirtualView(IView view) in /_/src/Core/src/Handlers/Layout/LayoutHandler.Android.cs:line 41
[mono-rt]    at Microsoft.Maui.Handlers.ViewHandler`2[[Microsoft.Maui.ILayout, Microsoft.Maui, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null],[Microsoft.Maui.Platform.LayoutViewGroup, Microsoft.Maui, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null]].SetVirtualView(IElement view) in /_/src/Core/src/Handlers/View/ViewHandlerOfT.cs:line 56
[mono-rt]    at Microsoft.Maui.Controls.Element.SetHandler(IElementHandler newHandler) in /_/src/Controls/src/Core/Element/Element.cs:line 987
[mono-rt]    at Microsoft.Maui.Controls.Element.set_Handler(IElementHandler value) in /_/src/Controls/src/Core/Element/Element.cs:line 929
[mono-rt]    at Microsoft.Maui.Controls.VisualElement.Microsoft.Maui.IElement.set_Handler(IElementHandler value) in /_/src/Controls/src/Core/VisualElement/VisualElement.cs:line 2074
[mono-rt]    at Microsoft.Maui.Platform.ElementExtensions.ToHandler(IElement view, IMauiContext context) in /_/src/Core/src/Platform/ElementExtensions.cs:line 96
[mono-rt]    at Microsoft.Maui.Platform.ElementExtensions.ToPlatform(IElement view, IMauiContext context) in /_/src/Core/src/Platform/ElementExtensions.cs:line 127
[mono-rt]    at Microsoft.Maui.Handlers.LayoutHandler.SetVirtualView(IView view) in /_/src/Core/src/Handlers/Layout/LayoutHandler.Android.cs:line 41
[mono-rt]    at Microsoft.Maui.Handlers.ViewHandler`2[[Microsoft.Maui.ILayout, Microsoft.Maui, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null],[Microsoft.Maui.Platform.LayoutViewGroup, Microsoft.Maui, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null]].SetVirtualView(IElement view) in /_/src/Core/src/Handlers/View/ViewHandlerOfT.cs:line 56
[mono-rt]    at Microsoft.Maui.Controls.Element.SetHandler(IElementHandler newHandler) in /_/src/Controls/src/Core/Element/Element.cs:line 987
[mono-rt]    at Microsoft.Maui.Controls.Element.set_Handler(IElementHandler value) in /_/src/Controls/src/Core/Element/Element.cs:line 929
[mono-rt]    at Microsoft.Maui.Controls.VisualElement.Microsoft.Maui.IElement.set_Handler(IElementHandler value) in /_/src/Controls/src/Core/VisualElement/VisualElement.cs:line 2074
[mono-rt]    at Microsoft.Maui.Platform.ElementExtensions.ToHandler(IElement view, IMauiContext context) in /_/src/Core/src/Platform/ElementExtensions.cs:line 96
[mono-rt]    at Microsoft.Maui.Platform.ElementExtensions.ToPlatform(IElement view, IMauiContext context) in /_/src/Core/src/Platform/ElementExtensions.cs:line 127
[mono-rt]    at Microsoft.Maui.Handlers.ContentViewHandler.UpdateContent(IContentViewHandler handler) in /_/src/Core/src/Handlers/ContentView/ContentViewHandler.Android.cs:line 42
[mono-rt]    at Microsoft.Maui.Handlers.ContentViewHandler.MapContent(IContentViewHandler handler, IContentView page) in /_/src/Core/src/Handlers/ContentView/ContentViewHandler.Android.cs:line 47
[mono-rt]    at Microsoft.Maui.PropertyMapper`2.<>c__DisplayClass5_0[[Microsoft.Maui.IContentView, Microsoft.Maui, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null],[Microsoft.Maui.Handlers.IContentViewHandler, Microsoft.Maui, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null]].<Add>b__0(IElementHandler h, IElement v) in /_/src/Core/src/PropertyMapper.cs:line 172
[mono-rt]    at Microsoft.Maui.PropertyMapper.UpdatePropertyCore(String key, IElementHandler viewHandler, IElement virtualView) in /_/src/Core/src/PropertyMapper.cs:line 47
[mono-rt]    at Microsoft.Maui.PropertyMapper.UpdateProperties(IElementHandler viewHandler, IElement virtualView) in /_/src/Core/src/PropertyMapper.cs:line 82
[mono-rt]    at Microsoft.Maui.Handlers.ElementHandler.SetVirtualView(IElement view) in /_/src/Core/src/Handlers/Element/ElementHandler.cs:line 79
[mono-rt]    at Microsoft.Maui.Handlers.ViewHandler`2[[Microsoft.Maui.IContentView, Microsoft.Maui, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null],[Microsoft.Maui.Platform.ContentViewGroup, Microsoft.Maui, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null]].SetVirtualView(IView view) in /_/src/Core/src/Handlers/View/ViewHandlerOfT.cs:line 53
[mono-rt]    at Microsoft.Maui.Handlers.ContentViewHandler.SetVirtualView(IView view) in /_/src/Core/src/Handlers/ContentView/ContentViewHandler.Android.cs:line 26
[mono-rt]    at Microsoft.Maui.Handlers.ViewHandler`2[[Microsoft.Maui.IContentView, Microsoft.Maui, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null],[Microsoft.Maui.Platform.ContentViewGroup, Microsoft.Maui, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null]].SetVirtualView(IElement view) in /_/src/Core/src/Handlers/View/ViewHandlerOfT.cs:line 56
[mono-rt]    at Microsoft.Maui.Controls.Element.SetHandler(IElementHandler newHandler) in /_/src/Controls/src/Core/Element/Element.cs:line 987
[mono-rt]    at Microsoft.Maui.Controls.Element.set_Handler(IElementHandler value) in /_/src/Controls/src/Core/Element/Element.cs:line 929
[mono-rt]    at Microsoft.Maui.Controls.VisualElement.Microsoft.Maui.IElement.set_Handler(IElementHandler value) in /_/src/Controls/src/Core/VisualElement/VisualElement.cs:line 2074
[mono-rt]    at Microsoft.Maui.Platform.ElementExtensions.ToHandler(IElement view, IMauiContext context) in /_/src/Core/src/Platform/ElementExtensions.cs:line 96
[mono-rt]    at Microsoft.Maui.Platform.ElementExtensions.ToPlatform(IElement view, IMauiContext context) in /_/src/Core/src/Platform/ElementExtensions.cs:line 127
[mono-rt]    at Microsoft.Maui.Handlers.LayoutHandler.SetVirtualView(IView view) in /_/src/Core/src/Handlers/Layout/LayoutHandler.Android.cs:line 41
[mono-rt]    at Microsoft.Maui.Handlers.ViewHandler`2[[Microsoft.Maui.ILayout, Microsoft.Maui, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null],[Microsoft.Maui.Platform.LayoutViewGroup, Microsoft.Maui, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null]].SetVirtualView(IElement view) in /_/src/Core/src/Handlers/View/ViewHandlerOfT.cs:line 56
[mono-rt]    at Microsoft.Maui.Controls.Element.SetHandler(IElementHandler newHandler) in /_/src/Controls/src/Core/Element/Element.cs:line 987
[mono-rt]    at Microsoft.Maui.Controls.Element.set_Handler(IElementHandler value) in /_/src/Controls/src/Core/Element/Element.cs:line 929
[mono-rt]    at Microsoft.Maui.Controls.VisualElement.Microsoft.Maui.IElement.set_Handler(IElementHandler value) in /_/src/Controls/src/Core/VisualElement/VisualElement.cs:line 2074
[mono-rt]    at Microsoft.Maui.Platform.ElementExtensions.ToHandler(IElement view, IMauiContext context) in /_/src/Core/src/Platform/ElementExtensions.cs:line 96
[mono-rt]    at Microsoft.Maui.Platform.ElementExtensions.ToPlatform(IElement view, IMauiContext context) in /_/src/Core/src/Platform/ElementExtensions.cs:line 127
[mono-rt]    at Microsoft.Maui.Handlers.LayoutHandler.SetVirtualView(IView view) in /_/src/Core/src/Handlers/Layout/LayoutHandler.Android.cs:line 41
[mono-rt]    at Microsoft.Maui.Handlers.ViewHandler`2[[Microsoft.Maui.ILayout, Microsoft.Maui, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null],[Microsoft.Maui.Platform.LayoutViewGroup, Microsoft.Maui, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null]].SetVirtualView(IElement view) in /_/src/Core/src/Handlers/View/ViewHandlerOfT.cs:line 56
[mono-rt]    at Microsoft.Maui.Controls.Element.SetHandler(IElementHandler newHandler) in /_/src/Controls/src/Core/Element/Element.cs:line 987
[mono-rt]    at Microsoft.Maui.Controls.Element.set_Handler(IElementHandler value) in /_/src/Controls/src/Core/Element/Element.cs:line 929
[mono-rt]    at Microsoft.Maui.Controls.VisualElement.Microsoft.Maui.IElement.set_Handler(IElementHandler value) in /_/src/Controls/src/Core/VisualElement/VisualElement.cs:line 2074
[mono-rt]    at Microsoft.Maui.Platform.ElementExtensions.ToHandler(IElement view, IMauiContext context) in /_/src/Core/src/Platform/ElementExtensions.cs:line 96
[mono-rt]    at Microsoft.Maui.Platform.ElementExtensions.ToPlatform(IElement view, IMauiContext context) in /_/src/Core/src/Platform/ElementExtensions.cs:line 127
[mono-rt]    at Microsoft.Maui.Handlers.ContentViewHandler.UpdateContent(IContentViewHandler handler) in /_/src/Core/src/Handlers/ContentView/ContentViewHandler.Android.cs:line 42
[mono-rt]    at Microsoft.Maui.Handlers.ContentViewHandler.MapContent(IContentViewHandler handler, IContentView page) in /_/src/Core/src/Handlers/ContentView/ContentViewHandler.Android.cs:line 47
[mono-rt]    at Microsoft.Maui.PropertyMapper`2.<>c__DisplayClass5_0[[Microsoft.Maui.IContentView, Microsoft.Maui, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null],[Microsoft.Maui.Handlers.IContentViewHandler, Microsoft.Maui, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null]].<Add>b__0(IElementHandler h, IElement v) in /_/src/Core/src/PropertyMapper.cs:line 172
[mono-rt]    at Microsoft.Maui.PropertyMapper.UpdatePropertyCore(String key, IElementHandler viewHandler, IElement virtualView) in /_/src/Core/src/PropertyMapper.cs:line 47
[mono-rt]    at Microsoft.Maui.PropertyMapper.UpdateProperties(IElementHandler viewHandler, IElement virtualView) in /_/src/Core/src/PropertyMapper.cs:line 82
[mono-rt]    at Microsoft.Maui.Handlers.ElementHandler.SetVirtualView(IElement view) in /_/src/Core/src/Handlers/Element/ElementHandler.cs:line 79
[mono-rt]    at Microsoft.Maui.Handlers.ViewHandler`2[[Microsoft.Maui.IContentView, Microsoft.Maui, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null],[Microsoft.Maui.Platform.ContentViewGroup, Microsoft.Maui, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null]].SetVirtualView(IView view) in /_/src/Core/src/Handlers/View/ViewHandlerOfT.cs:line 53
[mono-rt]    at Microsoft.Maui.Handlers.ContentViewHandler.SetVirtualView(IView view) in /_/src/Core/src/Handlers/ContentView/ContentViewHandler.Android.cs:line 26
[mono-rt]    at Microsoft.Maui.Handlers.ViewHandler`2[[Microsoft.Maui.IContentView, Microsoft.Maui, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null],[Microsoft.Maui.Platform.ContentViewGroup, Microsoft.Maui, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null]].SetVirtualView(IElement view) in /_/src/Core/src/Handlers/View/ViewHandlerOfT.cs:line 56
[mono-rt]    at Microsoft.Maui.Controls.Element.SetHandler(IElementHandler newHandler) in /_/src/Controls/src/Core/Element/Element.cs:line 987
[mono-rt]    at Microsoft.Maui.Controls.Element.set_Handler(IElementHandler value) in /_/src/Controls/src/Core/Element/Element.cs:line 929
[mono-rt]    at Microsoft.Maui.Controls.VisualElement.Microsoft.Maui.IElement.set_Handler(IElementHandler value) in /_/src/Controls/src/Core/VisualElement/VisualElement.cs:line 2074
[mono-rt]    at Microsoft.Maui.Platform.ElementExtensions.ToHandler(IElement view, IMauiContext context) in /_/src/Core/src/Platform/ElementExtensions.cs:line 96
[mono-rt]    at Microsoft.Maui.Platform.ElementExtensions.ToPlatform(IElement view, IMauiContext context) in /_/src/Core/src/Platform/ElementExtensions.cs:line 127
[mono-rt]    at Microsoft.Maui.Handlers.BorderHandler.UpdateContent(IBorderHandler handler) in /_/src/Core/src/Handlers/Border/BorderHandler.Android.cs:line 45
[mono-rt]    at Microsoft.Maui.Handlers.BorderHandler.MapContent(IBorderHandler handler, IBorderView border) in /_/src/Core/src/Handlers/Border/BorderHandler.cs:line 163
[mono-rt]    at Microsoft.Maui.PropertyMapper`2.<>c__DisplayClass5_0[[Microsoft.Maui.IBorderView, Microsoft.Maui, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null],[Microsoft.Maui.Handlers.IBorderHandler, Microsoft.Maui, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null]].<Add>b__0(IElementHandler h, IElement v) in /_/src/Core/src/PropertyMapper.cs:line 172
[mono-rt]    at Microsoft.Maui.PropertyMapper.UpdatePropertyCore(String key, IElementHandler viewHandler, IElement virtualView) in /_/src/Core/src/PropertyMapper.cs:line 47
[mono-rt]    at Microsoft.Maui.PropertyMapper.UpdateProperties(IElementHandler viewHandler, IElement virtualView) in /_/src/Core/src/PropertyMapper.cs:line 82
[mono-rt]    at Microsoft.Maui.Handlers.ElementHandler.SetVirtualView(IElement view) in /_/src/Core/src/Handlers/Element/ElementHandler.cs:line 79
[mono-rt]    at Microsoft.Maui.Handlers.ViewHandler`2[[Microsoft.Maui.IBorderView, Microsoft.Maui, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null],[Microsoft.Maui.Platform.ContentViewGroup, Microsoft.Maui, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null]].SetVirtualView(IView view) in /_/src/Core/src/Handlers/View/ViewHandlerOfT.cs:line 53
[mono-rt]    at Microsoft.Maui.Handlers.BorderHandler.SetVirtualView(IView view) in /_/src/Core/src/Handlers/Border/BorderHandler.Android.cs:line 28
[mono-rt]    at Microsoft.Maui.Handlers.ViewHandler`2[[Microsoft.Maui.IBorderView, Microsoft.Maui, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null],[Microsoft.Maui.Platform.ContentViewGroup, Microsoft.Maui, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null]].SetVirtualView(IElement view) in /_/src/Core/src/Handlers/View/ViewHandlerOfT.cs:line 56
[mono-rt]    at Microsoft.Maui.Controls.Element.SetHandler(IElementHandler newHandler) in /_/src/Controls/src/Core/Element/Element.cs:line 987
[mono-rt]    at Microsoft.Maui.Controls.Element.set_Handler(IElementHandler value) in /_/src/Controls/src/Core/Element/Element.cs:line 929
[mono-rt]    at Microsoft.Maui.Controls.VisualElement.Microsoft.Maui.IElement.set_Handler(IElementHandler value) in /_/src/Controls/src/Core/VisualElement/VisualElement.cs:line 2074
[mono-rt]    at Microsoft.Maui.Platform.ElementExtensions.ToHandler(IElement view, IMauiContext context) in /_/src/Core/src/Platform/ElementExtensions.cs:line 96
[mono-rt]    at Microsoft.Maui.Platform.ElementExtensions.ToPlatform(IElement view, IMauiContext context) in /_/src/Core/src/Platform/ElementExtensions.cs:line 127
[mono-rt]    at Microsoft.Maui.Handlers.ContentViewHandler.UpdateContent(IContentViewHandler handler) in /_/src/Core/src/Handlers/ContentView/ContentViewHandler.Android.cs:line 42
[mono-rt]    at Microsoft.Maui.Handlers.ContentViewHandler.MapContent(IContentViewHandler handler, IContentView page) in /_/src/Core/src/Handlers/ContentView/ContentViewHandler.Android.cs:line 47
[mono-rt]    at Microsoft.Maui.PropertyMapper`2.<>c__DisplayClass5_0[[Microsoft.Maui.IContentView, Microsoft.Maui, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null],[Microsoft.Maui.Handlers.IContentViewHandler, Microsoft.Maui, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null]].<Add>b__0(IElementHandler h, IElement v) in /_/src/Core/src/PropertyMapper.cs:line 172
[mono-rt]    at Microsoft.Maui.PropertyMapper.UpdatePropertyCore(String key, IElementHandler viewHandler, IElement virtualView) in /_/src/Core/src/PropertyMapper.cs:line 47
[mono-rt]    at Microsoft.Maui.PropertyMapper.UpdateProperties(IElementHandler viewHandler, IElement virtualView) in /_/src/Core/src/PropertyMapper.cs:line 82
[mono-rt]    at Microsoft.Maui.Handlers.ElementHandler.SetVirtualView(IElement view) in /_/src/Core/src/Handlers/Element/ElementHandler.cs:line 79
[mono-rt]    at Microsoft.Maui.Handlers.ViewHandler`2[[Microsoft.Maui.IContentView, Microsoft.Maui, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null],[Microsoft.Maui.Platform.ContentViewGroup, Microsoft.Maui, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null]].SetVirtualView(IView view) in /_/src/Core/src/Handlers/View/ViewHandlerOfT.cs:line 53
[mono-rt]    at Microsoft.Maui.Handlers.ContentViewHandler.SetVirtualView(IView view) in /_/src/Core/src/Handlers/ContentView/ContentViewHandler.Android.cs:line 26
[mono-rt]    at Microsoft.Maui.Handlers.ViewHandler`2[[Microsoft.Maui.IContentView, Microsoft.Maui, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null],[Microsoft.Maui.Platform.ContentViewGroup, Microsoft.Maui, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null]].SetVirtualView(IElement view) in /_/src/Core/src/Handlers/View/ViewHandlerOfT.cs:line 56
[mono-rt]    at Microsoft.Maui.Controls.Element.SetHandler(IElementHandler newHandler) in /_/src/Controls/src/Core/Element/Element.cs:line 987
[mono-rt]    at Microsoft.Maui.Controls.Element.set_Handler(IElementHandler value) in /_/src/Controls/src/Core/Element/Element.cs:line 929
[mono-rt]    at Microsoft.Maui.Controls.VisualElement.Microsoft.Maui.IElement.set_Handler(IElementHandler value) in /_/src/Controls/src/Core/VisualElement/VisualElement.cs:line 2074
[mono-rt]    at Microsoft.Maui.Platform.ElementExtensions.ToHandler(IElement view, IMauiContext context) in /_/src/Core/src/Platform/ElementExtensions.cs:line 96
[mono-rt]    at Microsoft.Maui.Platform.ElementExtensions.ToPlatform(IElement view, IMauiContext context) in /_/src/Core/src/Platform/ElementExtensions.cs:line 127
[mono-rt]    at Microsoft.Maui.Handlers.LayoutHandler.SetVirtualView(IView view) in /_/src/Core/src/Handlers/Layout/LayoutHandler.Android.cs:line 41
[mono-rt]    at Microsoft.Maui.Handlers.ViewHandler`2[[Microsoft.Maui.ILayout, Microsoft.Maui, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null],[Microsoft.Maui.Platform.LayoutViewGroup, Microsoft.Maui, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null]].SetVirtualView(IElement view) in /_/src/Core/src/Handlers/View/ViewHandlerOfT.cs:line 56
[mono-rt]    at Microsoft.Maui.Controls.Element.SetHandler(IElementHandler newHandler) in /_/src/Controls/src/Core/Element/Element.cs:line 987
[mono-rt]    at Microsoft.Maui.Controls.Element.set_Handler(IElementHandler value) in /_/src/Controls/src/Core/Element/Element.cs:line 929
[mono-rt]    at Microsoft.Maui.Controls.VisualElement.Microsoft.Maui.IElement.set_Handler(IElementHandler value) in /_/src/Controls/src/Core/VisualElement/VisualElement.cs:line 2074
[mono-rt]    at Microsoft.Maui.Platform.ElementExtensions.ToHandler(IElement view, IMauiContext context) in /_/src/Core/src/Platform/ElementExtensions.cs:line 96
[mono-rt]    at Microsoft.Maui.Platform.ElementExtensions.ToPlatform(IElement view, IMauiContext context) in /_/src/Core/src/Platform/ElementExtensions.cs:line 127
[mono-rt]    at Microsoft.Maui.Handlers.ScrollViewHandler.UpdateInsetView(IScrollView scrollView, IScrollViewHandler handler, ICrossPlatformLayout crossPlatformLayout) in /_/src/Core/src/Handlers/ScrollView/ScrollViewHandler.Android.cs:line 186
[mono-rt]    at Microsoft.Maui.Handlers.ScrollViewHandler.MapContent(IScrollViewHandler handler, IScrollView scrollView) in /_/src/Core/src/Handlers/ScrollView/ScrollViewHandler.Android.cs:line 114
[mono-rt]    at Microsoft.Maui.PropertyMapper`2.<>c__DisplayClass5_0[[Microsoft.Maui.IScrollView, Microsoft.Maui, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null],[Microsoft.Maui.Handlers.IScrollViewHandler, Microsoft.Maui, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null]].<Add>b__0(IElementHandler h, IElement v) in /_/src/Core/src/PropertyMapper.cs:line 172
[mono-rt]    at Microsoft.Maui.PropertyMapper.UpdatePropertyCore(String key, IElementHandler viewHandler, IElement virtualView) in /_/src/Core/src/PropertyMapper.cs:line 47
[mono-rt]    at Microsoft.Maui.PropertyMapper.UpdateProperties(IElementHandler viewHandler, IElement virtualView) in /_/src/Core/src/PropertyMapper.cs:line 82
[mono-rt]    at Microsoft.Maui.Handlers.ElementHandler.SetVirtualView(IElement view) in /_/src/Core/src/Handlers/Element/ElementHandler.cs:line 79
[mono-rt]    at Microsoft.Maui.Handlers.ViewHandler`2[[Microsoft.Maui.IScrollView, Microsoft.Maui, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null],[Microsoft.Maui.Platform.MauiScrollView, Microsoft.Maui, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null]].SetVirtualView(IView view) in /_/src/Core/src/Handlers/View/ViewHandlerOfT.cs:line 53
[mono-rt]    at Microsoft.Maui.Handlers.ViewHandler`2[[Microsoft.Maui.IScrollView, Microsoft.Maui, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null],[Microsoft.Maui.Platform.MauiScrollView, Microsoft.Maui, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null]].SetVirtualView(IElement view) in /_/src/Core/src/Handlers/View/ViewHandlerOfT.cs:line 56
[mono-rt]    at Microsoft.Maui.Controls.Element.SetHandler(IElementHandler newHandler) in /_/src/Controls/src/Core/Element/Element.cs:line 987
[mono-rt]    at Microsoft.Maui.Controls.Element.set_Handler(IElementHandler value) in /_/src/Controls/src/Core/Element/Element.cs:line 929
[mono-rt]    at Microsoft.Maui.Controls.VisualElement.Microsoft.Maui.IElement.set_Handler(IElementHandler value) in /_/src/Controls/src/Core/VisualElement/VisualElement.cs:line 2074
[mono-rt]    at Microsoft.Maui.Platform.ElementExtensions.ToHandler(IElement view, IMauiContext context) in /_/src/Core/src/Platform/ElementExtensions.cs:line 96
[mono-rt]    at Microsoft.Maui.Platform.ElementExtensions.ToPlatform(IElement view, IMauiContext context) in /_/src/Core/src/Platform/ElementExtensions.cs:line 127
[mono-rt]    at Microsoft.Maui.Handlers.LayoutHandler.SetVirtualView(IView view) in /_/src/Core/src/Handlers/Layout/LayoutHandler.Android.cs:line 41
[mono-rt]    at Microsoft.Maui.Handlers.ViewHandler`2[[Microsoft.Maui.ILayout, Microsoft.Maui, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null],[Microsoft.Maui.Platform.LayoutViewGroup, Microsoft.Maui, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null]].SetVirtualView(IElement view) in /_/src/Core/src/Handlers/View/ViewHandlerOfT.cs:line 56
[mono-rt]    at Microsoft.Maui.Controls.Element.SetHandler(IElementHandler newHandler) in /_/src/Controls/src/Core/Element/Element.cs:line 987
[mono-rt]    at Microsoft.Maui.Controls.Element.set_Handler(IElementHandler value) in /_/src/Controls/src/Core/Element/Element.cs:line 929
[mono-rt]    at Microsoft.Maui.Controls.VisualElement.Microsoft.Maui.IElement.set_Handler(IElementHandler value) in /_/src/Controls/src/Core/VisualElement/VisualElement.cs:line 2074
[mono-rt]    at Microsoft.Maui.Platform.ElementExtensions.ToHandler(IElement view, IMauiContext context) in /_/src/Core/src/Platform/ElementExtensions.cs:line 96
[mono-rt]    at Microsoft.Maui.Platform.ElementExtensions.ToPlatform(IElement view, IMauiContext context) in /_/src/Core/src/Platform/ElementExtensions.cs:line 127
[mono-rt]    at Microsoft.Maui.Handlers.ContentViewHandler.UpdateContent(IContentViewHandler handler) in /_/src/Core/src/Handlers/ContentView/ContentViewHandler.Android.cs:line 42
[mono-rt]    at Microsoft.Maui.Handlers.ContentViewHandler.MapContent(IContentViewHandler handler, IContentView page) in /_/src/Core/src/Handlers/ContentView/ContentViewHandler.Android.cs:line 47
[mono-rt]    at Microsoft.Maui.PropertyMapper`2.<>c__DisplayClass5_0[[Microsoft.Maui.IContentView, Microsoft.Maui, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null],[Microsoft.Maui.Handlers.IContentViewHandler, Microsoft.Maui, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null]].<Add>b__0(IElementHandler h, IElement v) in /_/src/Core/src/PropertyMapper.cs:line 172
[mono-rt]    at Microsoft.Maui.PropertyMapper.UpdatePropertyCore(String key, IElementHandler viewHandler, IElement virtualView) in /_/src/Core/src/PropertyMapper.cs:line 47
[mono-rt]    at Microsoft.Maui.PropertyMapper.UpdateProperties(IElementHandler viewHandler, IElement virtualView) in /_/src/Core/src/PropertyMapper.cs:line 82
[mono-rt]    at Microsoft.Maui.Handlers.ElementHandler.SetVirtualView(IElement view) in /_/src/Core/src/Handlers/Element/ElementHandler.cs:line 79
[mono-rt]    at Microsoft.Maui.Handlers.ViewHandler`2[[Microsoft.Maui.IContentView, Microsoft.Maui, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null],[Microsoft.Maui.Platform.ContentViewGroup, Microsoft.Maui, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null]].SetVirtualView(IView view) in /_/src/Core/src/Handlers/View/ViewHandlerOfT.cs:line 53
[mono-rt]    at Microsoft.Maui.Handlers.ContentViewHandler.SetVirtualView(IView view) in /_/src/Core/src/Handlers/ContentView/ContentViewHandler.Android.cs:line 26
[mono-rt]    at Microsoft.Maui.Handlers.ViewHandler`2[[Microsoft.Maui.IContentView, Microsoft.Maui, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null],[Microsoft.Maui.Platform.ContentViewGroup, Microsoft.Maui, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null]].SetVirtualView(IElement view) in /_/src/Core/src/Handlers/View/ViewHandlerOfT.cs:line 56
[mono-rt]    at Microsoft.Maui.Controls.Element.SetHandler(IElementHandler newHandler) in /_/src/Controls/src/Core/Element/Element.cs:line 987
[mono-rt]    at Microsoft.Maui.Controls.Element.set_Handler(IElementHandler value) in /_/src/Controls/src/Core/Element/Element.cs:line 929
[mono-rt]    at Microsoft.Maui.Controls.VisualElement.Microsoft.Maui.IElement.set_Handler(IElementHandler value) in /_/src/Controls/src/Core/VisualElement/VisualElement.cs:line 2074
[mono-rt]    at Microsoft.Maui.Platform.ElementExtensions.ToHandler(IElement view, IMauiContext context) in /_/src/Core/src/Platform/ElementExtensions.cs:line 96
[mono-rt]    at Microsoft.Maui.Platform.ElementExtensions.ToPlatform(IElement view, IMauiContext context) in /_/src/Core/src/Platform/ElementExtensions.cs:line 127
[mono-rt]    at Microsoft.Maui.Platform.ScopedFragment.OnCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) in /_/src/Core/src/Platform/Android/Navigation/ScopedFragment.cs:line 32
[mono-rt]    at AndroidX.Fragment.App.Fragment.n_OnCreateView_Landroid_view_LayoutInflater_Landroid_view_ViewGroup_Landroid_os_Bundle_(IntPtr jnienv, IntPtr native__this, IntPtr native_inflater, IntPtr native_container, IntPtr native_savedInstanceState) in C:\a\_work\1\s\generated\androidx.fragment.fragment\obj\Release
et6.0-android\generated\src\AndroidX.Fragment.App.Fragment.cs:line 2031
[mono-rt]    at Android.Runtime.JNINativeWrapper.Wrap_JniMarshal_PPLLL_L(_JniMarshal_PPLLL_L callback, IntPtr jnienv, IntPtr klazz, IntPtr p0, IntPtr p1, IntPtr p2) in /Users/runner/work/1/s/xamarin-android/src/Mono.Android/Android.Runtime/JNINativeWrapper.g.cs:line 363
[EGL_emulation] tid 18393: eglQuerySurface(1402): error 0x3001 (EGL_NOT_INITIALIZED)
[EGL_emulation] tid 18393: eglQuerySurface(1402): error 0x3001 (EGL_NOT_INITIALIZED)
[EGL_emulation] tid 18393: eglSwapBuffers(2160): error 0x3001 (EGL_NOT_INITIALIZED)
[OpenGLRenderer] Encountered EGL error 12289 EGL_NOT_INITIALIZED during rendering
[o.myapp.com] art/dt_fd_forward/dt_fd_forward.cc:323 - Failed to receive fds!: Success
[o.myapp.com] Failed to read message from agent control socket! Retrying: Bad file descriptor
[libc] FORTIFY: pthread_mutex_lock called on a destroyed mutex (0x7ac9093a1978)
[libc] Fatal signal 6 (SIGABRT), code -1 (SI_QUEUE) in tid 18393 (RenderThread), pid 18322 (o.myapp.com)

The only way I'm not getting this error is by setting my DrawingView Lines Binding to Mode=OneWayToSource. But, if I do that, would not be possible to load the signature from the view model.

VladislavAntonyuk Aug 2, 2024
Maintainer

The problem is not in binding but in Deserialization, that returns you null

nk-alex Aug 2, 2024
Author

@VladislavAntonyuk Was my fault, I had to initialize the binding to an empty ObservableCollection<DrawingLine>() in order to be able to bind it TwoWay.

I also double checked I was saving/loading the drawing properly.

Still unable to make DrawingView show the loaded drawing. Looks like DrawingView is ignoring external changes to its binding

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Drawing view - draw - save - load #2088

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Drawing view - draw - save - load #2088

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VladislavAntonyuk Aug 2, 2024 Maintainer

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