[Bug] Sharing with webView.ToPngAsync to e-mail generate blank image

[farukaf]

Description

When generating a png with webView.ToPngAsync is attached a blank image to the e-mail.

Steps to Reproduce

1. New Xamarin.Forms project
2. Configure Forms9Patch
3. In the page use a WebView and Navigate to any site in the WebView
4. Button/event calling webView.ToPngAsync
5. Send as e-mail

Expected Behavior

Attached website as a image.

Actual Behavior

Attached blank image

Basic Information

All tests above in Android, both emulator and physical device.

• Version with issue:
• IDE:

Microsoft Visual Studio Community 2019
Version 16.8.2
VisualStudio.16.Release/16.8.2+30717.126
Microsoft .NET Framework
Version 4.8.04084

Installed Version: Community

Visual C++ 2019   00435-60000-00000-AA570
Microsoft Visual C++ 2019

ASP.NET and Web Tools 2019   16.8.553.28003
ASP.NET and Web Tools 2019

ASP.NET Core Razor Language Services   16.1.0.2052803+84e121f1403378489b842e1797df2f3f5a49ac3c
Provides languages services for ASP.NET Core Razor.

ASP.NET Web Frameworks and Tools 2019   16.8.553.28003
For additional information, visit https://www.asp.net/

Azure App Service Tools v3.0.0   16.8.553.28003
Azure App Service Tools v3.0.0

Azure Functions and Web Jobs Tools   16.8.553.28003
Azure Functions and Web Jobs Tools

C# Tools   3.8.0-5.20567.16+53c5d7d3cf13d88978744a32a27c5f8350a8400a
C# components used in the IDE. Depending on your project type and settings, a different version of the compiler may be used.

Common Azure Tools   1.10
Provides common services for use by Azure Mobile Services and Microsoft Azure Tools.

Cookiecutter   16.8.20241.2
Provides tools for finding, instantiating and customizing templates in cookiecutter format.

Extensibility Message Bus   1.2.6 (master@34d6af2)
Provides common messaging-based MEF services for loosely coupled Visual Studio extension components communication and integration.

GitHub.VisualStudio   2.11.106.19330
A Visual Studio Extension that brings the GitHub Flow into Visual Studio.

IntelliCode Extension   1.0
IntelliCode Visual Studio Extension Detailed Info

Microsoft Azure Tools   2.9
Microsoft Azure Tools for Microsoft Visual Studio 2019 - v2.9.30924.1

Microsoft Continuous Delivery Tools for Visual Studio   0.4
Simplifying the configuration of Azure DevOps pipelines 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 Library Manager   2.1.113+g422d40002e.RR
Install client-side libraries easily to any web project

Microsoft MI-Based Debugger   1.0
Provides support for connecting Visual Studio to MI compatible debuggers

Microsoft Visual C++ Wizards   1.0
Microsoft Visual C++ Wizards

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   16.8.43 (00471f8)
Support for debugging Mono processes with Visual Studio.

Node.js Tools   1.5.20902.1 Commit Hash:b474efcb6f92db52a8f8e2e6a8cb9648476885cc
Adds support for developing and debugging Node.js apps in Visual Studio

NuGet Package Manager   5.8.0
NuGet Package Manager in Visual Studio. For more information about NuGet, visit https://docs.nuget.org/

ProjectServicesPackage Extension   1.0
ProjectServicesPackage Visual Studio Extension Detailed Info

Python   16.8.20241.2
Provides IntelliSense, projects, templates, debugging, interactive windows, and other support for Python developers.

Python - Conda support   16.8.20241.2
Conda support for Python projects.

Python - Django support   16.8.20241.2
Provides templates and integration for the Django web framework.

Python - IronPython support   16.8.20241.2
Provides templates and integration for IronPython-based projects.

Python - Profiling support   16.8.20241.2
Profiling support for Python projects.

SQL Server Data Tools   16.0.62010.06180
Microsoft SQL Server Data Tools

Syntax Visualizer   1.0
An extension for visualizing Roslyn SyntaxTrees.

Test Adapter for Boost.Test   1.0
Enables Visual Studio's testing tools with unit tests written for Boost.Test.  The use terms and Third Party Notices are available in the extension installation directory.

Test Adapter for Google Test   1.0
Enables Visual Studio's testing tools with unit tests written for Google Test.  The use terms and Third Party Notices are available in the extension installation directory.

TypeScript Tools   16.0.21016.2001
TypeScript Tools for Microsoft Visual Studio

Visual Basic Tools   3.8.0-5.20567.16+53c5d7d3cf13d88978744a32a27c5f8350a8400a
Visual Basic components used in the IDE. Depending on your project type and settings, a different version of the compiler may be used.

Visual F# Tools   16.8.0-beta.20507.4+da6be68280c89131cdba2045525b80890401defd
Microsoft Visual F# Tools

Visual Studio Code Debug Adapter Host Package   1.0
Interop layer for hosting Visual Studio Code debug adapters in Visual Studio

Visual Studio Container Tools Extensions   1.0
View, manage, and diagnose containers within Visual Studio.

Visual Studio Tools for CMake   1.0
Visual Studio Tools for CMake

Visual Studio Tools for Containers   1.0
Visual Studio Tools for Containers

VisualStudio.DeviceLog   1.0
Information about my package

VisualStudio.Foo   1.0
Information about my package

VisualStudio.Mac   1.0
Mac Extension for Visual Studio

Xamarin   16.8.000.255 (d16-8@d002176)
Visual Studio extension to enable development for Xamarin.iOS and Xamarin.Android.

Xamarin Designer   16.8.0.507 (remotes/origin/d16-8@e87b24884)
Visual Studio extension to enable Xamarin Designer tools in Visual Studio.

Xamarin Templates   16.8.112 (86385a3)
Templates for building iOS, Android, and Windows apps with Xamarin and Xamarin.Forms.

Xamarin.Android SDK   11.1.0.17 (d16-8/c0e2b8e)
Xamarin.Android Reference Assemblies and MSBuild support.
    Mono: be2226b
    Java.Interop: xamarin/java.interop/d16-8@79d9533
    ProGuard: Guardsquare/proguard/proguard6.2.2@ebe9000
    SQLite: xamarin/sqlite/3.32.1@1a3276b
    Xamarin.Android Tools: xamarin/xamarin-android-tools/d16-8@2fb1cbc


Xamarin.iOS and Xamarin.Mac SDK   14.4.1.3 (e30c41de3)
Xamarin.iOS and Xamarin.Mac Reference Assemblies and MSBuild support.

Also happens in a Enterprise

Microsoft Visual Studio Enterprise 2019
Version 16.8.3
VisualStudio.16.Release/16.8.3+30804.86
Microsoft .NET Framework
Version 4.8.04084

• Platform Target Frameworks:
• Android: 8.1 and 9.0

Reproduction Link - a link to a small demo project that reproduces this issue

https://github.com/farukaf/Xamarin-Forms9Patch

[farukaf]

I tried sharing https://github.com/ and https://clientsfromhell.net/ with WhatsApp and a long blank image instead of the expected.

I know this behavior would be normal in SPA or some kind of image rendering issue. Both links are not SPA but the second problem could be affected.

So I used http://tanaconta.com.br/ that is more static and the issue here is that only shows the first part of it, not showing the company 0800 at the bottom for example.

Generated by the .ToPngAsync

Expected

[farukaf]

Both e-mail and Whatsapp PNG with a static html generate the image with a long blank space on bottom.

webView.Source = new HtmlWebViewSource() { Html = @"
<html>
<head></head>
<body>
    <p>Mussum Ipsum, cacilds vidis litro abertis. Em pé sem cair, deitado sem dormir, sentado sem cochilar e fazendo pose. Casamentiss faiz malandris se pirulitá. Nullam volutpat risus nec leo commodo, ut interdum diam laoreet. Sed non consequat odio. Detraxit consequat et quo num tendi nada.</p>

    <p>Não sou faixa preta cumpadi, sou preto inteiris, inteiris. Suco de cevadiss, é um leite divinis, qui tem lupuliz, matis, aguis e fermentis. Viva Forevis aptent taciti sociosqu ad litora torquent. Diuretics paradis num copo é motivis de denguis.</p>

    <p>A ordem dos tratores não altera o pão duris. Nec orci ornare consequat. Praesent lacinia ultrices consectetur. Sed non ipsum felis. Suco de cevadiss deixa as pessoas mais interessantis. Mauris nec dolor in eros commodo tempor. Aenean aliquam molestie leo, vitae iaculis nisl.</p>

    <p>Delegadis gente finis, bibendum egestas augue arcu ut est. Interessantiss quisso pudia ce receita de bolis, mais bolis eu num gostis. Paisis, filhis, espiritis santis. Si u mundo tá muito paradis? Toma um mé que o mundo vai girarzis!</p>

    <p>Praesent vel viverra nisi. Mauris aliquet nunc non turpis scelerisque, eget. Mé faiz elementum girarzis, nisi eros vermeio. Quem manda na minha terra sou euzis! Posuere libero varius. Nullam a nisl ut ante blandit hendrerit. Aenean sit amet nisi.</p>

    <p>Tá deprimidis, eu conheço uma cachacis que pode alegrar sua vidis. Sapien in monti palavris qui num significa nadis i pareci latim. Admodum accumsan disputationi eu sit. Vide electram sadipscing et per. Atirei o pau no gatis, per gatis num morreus.</p>

    <p>Interagi no mé, cursus quis, vehicula ac nisi. Aenean aliquam molestie leo, vitae iaculis nisl. Mais vale um bebadis conhecidiss, que um alcoolatra anonimis. Praesent malesuada urna nisi, quis volutpat erat hendrerit non. Nam vulputate dapibus.</p>

    <p>Todo mundo vê os porris que eu tomo, mas ninguém vê os tombis que eu levo! In elementis mé pra quem é amistosis quis leo. Per aumento de cachacis, eu reclamis. Quem num gosta di mim que vai caçá sua turmis!</p>

    <p>Quem num gosta di mé, boa gentis num é. Si num tem leite então bota uma pinga aí cumpadi! Vehicula non. Ut sed ex eros. Vivamus sit amet nibh non tellus tristique interdum. Manduma pindureta quium dia nois paga.</p>

    <p>Copo furadis é disculpa de bebadis, arcu quam euismod magna. Cevadis im ampola pa arma uma pindureta. Leite de capivaris, leite de mula manquis sem cabeça. Pra lá , depois divoltis porris, paradis.</p>
</body>
</html>
" };

WhatsApp Image

E-mail Image

[wagenheimer]

I had several problems, both using "HTML to a PDF" and "HTML to PNG".

I came to the conclusion that PDF / PNG is being generated BEFORE HTML finishes rendering. I had several problems, tested it in different ways, and sometimes it worked, sometimes not. On iOS, it even got stuck on Spinning when generating the PDF.

To definitely resolve the problem, I displayed the HTML in a WebView first, and then on that screen I added a button to export to PNG or PDF. Since WebView already displayed HTML before generating PDF / PNG, it now worked 100% of the time on both iOS and Android.