Why is SKCanvasView PaintSurface triggered only when UWP (Universal Windows) is resized horizontally - xamarin.uwp

Question

I’m using Visual Studio 2017 to build a Windows UWP App.
My XML code is:
<?xml version="1.0" encoding="utf-8" ?>
<TabbedPage xmlns="http://xamarin.com/schemas/2014/forms"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
xmlns:forms="clr-namespace:SkiaSharp.Views.Forms;assembly=SkiaSharp.Views.Forms"
x:Class="Test_SMLibrary.Lines_and_Text">
<ContentPage>
<forms:SKCanvasView x:Name="CanvasView"
PaintSurface="CanvasView_PaintSurface"
IgnorePixelScaling="True"
HorizontalOptions="Fill"
VerticalOptions="Fill"/>
</ContentPage>
</TabbedPage>
and my C# code is:
namespace Test_SMLibrary {
[XamlCompilation(XamlCompilationOptions.Compile)]
public partial class Lines_and_Text {
public Lines_and_Text() {
InitializeComponent();
}
private void CanvasView_PaintSurface(object sender, SKPaintSurfaceEventArgs e) {
var surface = e.Surface;
var canvas = surface.Canvas;
var width = e.Info.Width;
var height = e.Info.Height;
canvas.Clear(SKColors.LightGray);
Debug.WriteLine("width: " + width + ", height: " + height);
}
}
}
The Debug write only occurs when the window is resized in the horizontal direction.
It is not executed when the window is resized in the vertical direction. Why?
Charles

Answer 1

Here is my versions:
Also, this is my environment:
Microsoft Visual Studio Professional 2017
Version 15.5.7
VisualStudio.15.Release/15.5.7+27130.2036
Microsoft .NET Framework
Version 4.7.02556
Installed Version: Professional
Visual Basic 2017 00369-60000-00001-AA307
Microsoft Visual Basic 2017
Visual C# 2017 00369-60000-00001-AA307
Microsoft Visual C# 2017
Visual F# 4.1 00369-60000-00001-AA307
Microsoft Visual F# 4.1
Application Insights Tools for Visual Studio Package 8.10.01106.1
Application Insights Tools for Visual Studio
ASP.NET and Web Tools 2017 15.0.31129.0
ASP.NET and Web Tools 2017
ASP.NET Core Razor Language Services 1.0
Provides languages services for ASP.NET Core Razor.
ASP.NET Web Frameworks and Tools 2017 5.2.51007.0
For additional information, visit https://www.asp.net/
Azure App Service Tools v3.0.0 15.0.31106.0
Azure App Service Tools v3.0.0
Clear Recent 1.0.0
Clears recent projects and files lists
Common Azure Tools 1.10
Provides common services for use by Azure Mobile Services and Microsoft Azure Tools.
Cookiecutter 3.0.17320.1
Provides tools for finding, instantiating and customizing templates in cookiecutter format.
JavaScript Language Service 2.0
JavaScript Language Service
JavaScript Project System 2.0
JavaScript Project System
JavaScript UWP Project System 2.0
JavaScript UWP Project System
JetBrains ReSharper Ultimate 2017.3.2 Build 111.0.20180201.63358
JetBrains ReSharper Ultimate package for Microsoft Visual Studio. For more information about ReSharper Ultimate, visit http://www.jetbrains.com/resharper. Copyright © 2018 JetBrains, Inc.
Merq 1.1.17-rc (cba4571)
Command Bus, Event Stream and Async Manager for Visual Studio extensions.
Microsoft Continuous Delivery Tools for Visual Studio 0.3
Simplifying the configuration of continuous build integration and continuous build delivery from within the Visual Studio IDE.
Microsoft JVM Debugger 1.0
Provides support for connecting the Visual Studio debugger to JDWP compatible Java Virtual Machines
Microsoft MI-Based Debugger 1.0
Provides support for connecting Visual Studio to MI compatible debuggers
Microsoft Visual Studio Tools for Containers 1.1
Develop, run, validate your ASP.NET Core applications in the target environment. F5 your application directly into a container with debugging, or CTRL + F5 to edit & refresh your app without having to rebuild the container.
Microsoft Visual Studio VC Package 1.0
Microsoft Visual Studio VC Package
Mono Debugging for Visual Studio 4.8.4-pre (3fe64e3)
Support for debugging Mono processes with Visual Studio.
NuGet Package Manager 4.5.0
NuGet Package Manager in Visual Studio. For more information about NuGet, visit http://docs.nuget.org/.
Python 3.0.17320.1
Provides IntelliSense, projects, templates, debugging, interactive windows, and other support for Python developers.
Python - IronPython support 3.0.17320.1
Provides templates and integration for IronPython-based projects.
Python - Profiling support 3.0.17320.1
Profiling support for Python projects.
R Tools for Visual Studio 1.3.31108.1213
Provides project system, R Interactive window, plotting, and more for the R programming language.
RelayCommand Extension 1.0
RelayCommand Visual Studio Extension Detailed Info
SQL Server Data Tools 15.1.61710.120
Microsoft SQL Server Data Tools
TypeScript Tools 15.5.11025.1
TypeScript Tools for Microsoft Visual Studio
Visual Studio Code Debug Adapter Host Package 1.0
Interop layer for hosting Visual Studio Code debug adapters in Visual Studio
Visual Studio Tools for AI 0.3.3.0
An integrated development environment for AI / Deep Learning application development.
Visual Studio Tools for AI: Azure Batch AI 0.3.3.0
This package provides Azure Batch AI support in Visual Studio Tools for AI.
Visual Studio Tools for AI: Azure Machine Learning 0.3.3.0
This package provides Azure Machine Learning support in Visual Studio Tools for AI.
Visual Studio Tools for AI: Remote Machine 0.3.3.0
This package provides Remote Machine support in Visual Studio Tools for AI.
Visual Studio Tools for Universal Windows Apps 15.0.27130.2036
The Visual Studio Tools for Universal Windows apps allow you to build a single universal app experience that can reach every device running Windows 10: phone, tablet, PC, and more. It includes the Microsoft Windows 10 Software Development Kit.
VisualStudio.Mac 1.0
Mac Extension for Visual Studio
Xamarin 4.8.0.760 (fc93f3f5b)
Visual Studio extension to enable development for Xamarin.iOS and Xamarin.Android.
Xamarin Designer 4.8.188 (c5813fa34)
Visual Studio extension to enable Xamarin Designer tools in Visual Studio.
Xamarin.Android SDK 8.1.5.0 (HEAD/75f8c6838)
Xamarin.Android Reference Assemblies and MSBuild support.
Xamarin.iOS and Xamarin.Mac SDK 11.6.1.4 (db807ec)
Xamarin.iOS and Xamarin.Mac Reference Assemblies and MSBuild support.
Charles