What’s new for the WinForms Visual Basic Application Framework

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What’s new for the WinForms Visual Basic Application Framework

Klaus Loeffelmann

Melissa Trevino

March 9th, 202334

.NET from version .NET Core 3.1 up to .NET 7 has plenty of advantages over .NET

Framework: it provides performance improvements in almost every area, and those

improvements were an ongoing effort over each .NET version. The

latest improvements in .NET

6 and

.NET

7 are

really worth checking out.

Migrating your Windows Forms (WinForms) Visual Basic Apps to .NET 6/7+ also

allows to adopt modern technologies which are not (or are no longer) supported in .NET

Framework. EFCore is one example: it is

a modern Entity Framework data access technology that enables .NET developers to

work with database backends using .NET objects. Although it is not natively

supported for VB by Microsoft, it is designed in a way that it is easy for the

community to build up on it and provide code generation support for additional

languages like Visual Basic. In

that context there are also changes and improvements in the new WinForms

Out-of-Process Designer for .NET, especially around Object Data

Sources.

For the WinForms .NET runtime, there are a series of improvements in different

areas which have been introduced with the latest releases of .NET:

The new Visual Basic Application Framework Experience

In contrast to the project property Application Framework Designer experience in

earlier versions of Visual Studio and for .NET Framework, you will noticed that

the project properties UI in Visual Studio has changed. It’s style is now in

parity with the project properties experience for other .NET project types: we

have invested into modernizing the experience for developers, focusing on

enhancing productivity and a modern look and feel.

We’ve added theming and search to the new experience. If this is your first time

you’re working with the new project properties experience in Visual Studio, it’s

a good idea to read up on the the introductory

blog.

In contrast to C# projects, Visual Basic Application Framework projects use a

special file for storing the Application Framework project settings: the

Application.myapp file. We’ll talk more about the technical details of how

this file connects the project settings to the VB project specific code

generation of the

Code:

My

namespace later, but one thing to keep in mind is how the

UI translates each property’s value to this file:

• Windows Visual Styles is to determine if the application will use the most
  
  current version for the Control Library comctl.dll to provide control
  
  rendering with modern visual styling. This setting translates to the value
  
  
  Code:

  EnableVisualStyles
  of type
  Code:

  Boolean
  inside of Application.myapp.
  
  
• Single-instance application is to determine if the application will prevent
  
  users from running multiple instances of the application. This setting is
  
  switched off by default, which allows multiple instances of the application to
  
  be run concurrently. This setting translates to the value
  Code:

  SingleInstance
  of
  
  type
  Code:

  Boolean
  .
  
  
• Save user settings on exit is to determine if the application settings are
  
  automatically saved when an app is about to shut down. The settings can be
  
  changed with the settings editor. In contrast to .NET Framework, a new Visual
  
  Basic Application Framework App doesn’t contain a settings file by default,
  
  but you can easily insert one over the project properties, should you need
  
  one, and then manage the settings
  
  interactively.
  
  Adding to the list of settings automatically generates respective code, which
  
  can be easily access over the
  Code:

  My
  object in the Visual Basic Application
  
  Framework at
  
  runtime.
  
  This settings translates to the value
  Code:

  SaveMySettingsOnExit
  of type
  
  
  Code:

  Boolean
  .
  
  
• High DPI mode is to identify the application-wide HighDpiMode for the
  
  application. Note that this setting can be programmatically overridden through
  
  the
  Code:

  HighDpiMode
  
  property
  
  of the
  Code:

  ApplyApplicationDefaultsEventArgs
  of the
  Code:

  ApplyApplicationDefaults
  
  
  application event. Choose from the following setting:
  
  • DPI unaware (0): The application window does not scale for DPI changes and
    
    always assumes a scale factor of 100%. For higher resolutions, this will
    
    make text and fine drawings more blurry, but may impose the best setting for
    
    some apps which demand a high backwards compatibility in rendering content.
    
    
  • DPI unaware GDI scaled (4): similar to DPI unaware, but improves the
    
    quality of GDI/GDI+ based on content. Please note that this mode will not
    
    work as expected, when you have enabled double
    
    buffering
    
    for control rendering via
    Code:

    OnPaint
    and related functionality.
    
    
  • Per monitor (2): Per-Monitor DPI allows individual displays to have their
    
    own DPI scaling setting. WinForms doesn’t optimize for this mode, and
    
    Per-Monitor V2 should be used instead.
    
    
  • Per monitor V2 (3): Per-Monitor V2 offers more advanced scaling features
    
    such as improved support for mixed DPI environments, improved display
    
    enumeration, and support for dynamically scaling on-client area of windows.
    
    In WinForms common controls are optimized for this high dpi mode. Please
    
    note the events
    
    Form.DpiChange,
    
    Control.DpiChangedAfterParent
    
    and
    
    Control.DpiChangeBeforeParent,
    
    when your app need to scale up or down content based on a changed DPI
    
    environment, for example, when the user of your app has dragged a Form from
    
    one monitor to another monitor with a different DPI setting.
    
    
  • System aware (1): The application queries for the DPI of the primary
    
    monitor once and uses this for the application on all monitors. When content
    
    in Forms is dragged from one monitor to another with a different HighDPI
    
    setting, content might become blurry. SystemAware is WinForm’s most
    
    compatible high-dpi rendering mode for all supported controls.
    
  
  
• Authentication mode is to specify the method of identifying the logged-on
  
  user, when needed. The setting translates to the value
  Code:

  AuthenticationMode
  as
  
  an enum value of type
  Code:

  Integer
  :
  
  • 0: The
    Code:

    WindowsFormsApplicationBase(AuthenticationMode)
    constructor does
    
    not automatically initialize the principal for the application’s main
    
    thread. It’s completely the developer’s task, to manage authentication for
    
    the user.
    
    
  • 1: The
    Code:

    WindowsFormsApplicationBase(AuthenticationMode)
    constructor
    
    initializes the principal for the application’s main thread with the current
    
    user’s Windows user info.
    
  
  
• Shutdown mode is to to indicate which condition causes the application to
  
  shut down. This setting translates to the value
  Code:

  ShutdownMode
  as an enum
  
  value of type
  Code:

  Integer
  (Note: Please also refer to the application event
  
  ShutDown
  
  and the further remarks down below.):
  
  • 0: When the main form closes.
    
    
  • 1: Only after the last form closes.
    
  
  
• Splash screen represents the name of the form to be used as a splash screen
  
  for the application. Note that the file name does not need to include the
  
  extension (.vb). This setting translates to the value
  Code:

  SplashScreen
  of type
  
  
  Code:

  String
  .
  
  

  Note: you will may be missing the settings for the Splash dialog up to
  
  Visual Studio 2022 version 17.5. For a workaround, read the comments in
  
  the section “A look behind the scenes”. To recap: a “Splash” dialog is
  
  typically displayed for a few seconds when an application is launched.
  
  Visual Basic has an item template which you can use to add a basic splash
  
  dialog to your project. It usually displays the logo or name of the
  
  application, along with some kind of animation or visual effects, to give
  
  users the impression that the application is loading or initializing. The
  
  term “splash” in this context is used because the dialog is designed to
  
  create a splash or impact on the user, drawing their attention to the
  
  application while it loads.

  
  
• Application Framework is saved both in the Application.myapp file and the
  
  .vbproj file:
  
  • Application.myapp saves the setting
    Code:

    MySubMain
    of type
    Code:

    Boolean
    to
    
    identify if the Application Framework is enabled.
    
    
  • .vbproj uses the setting
    Code:

    MyType
    for identifying the usage of the
    
    Application Framework for a VB project. If the Application Framework is
    
    enabled, the value is WindowsForms; if the Application Framework is
    
    disabled, the value is WindowsFormsWithCustomSubMain.
    
  
  
• Startup object is the name of the form that will be used as the entry
  
  point, without its filename extension. Note: this property is found in the
  
  project property Settings under the General section, and not in the
  
  Application Framework section. This setting translates to the value
  Code:

  MainForm
  of type
  
  
  Code:

  String
  , when the Application Framework is activated. The start object setting in
  
  the .vbproj file is ignored in that case – see also the comments below on this
  
  topic.
  

Custom constants new look

We are introducing a new custom constants-control in the modernized Project

Property Pages for VB Projects, that allows to encode the input to the format

key=”value”. Our goal is that users will be able to input their custom constants

in a more streamlined key-value pair format, thus enhancing their productivity.

Feedback is welcomed – if you have any comments or suggestions, feel free to

reach out to the project system

team by filing a new issue or

comment on existing ones.

A look behind the scenes of the WinForms VB Application Framework

The way basic properties and behaviors of a WinForms app are controlled and configured is fundamentally different between C# and Visual Basic. In C#, every app

starts with a static method called

Code:

main

which can usually be found in a file

called Program.cs, and in that

Code:

main

method all the setting get applied.

That is different in Visual Basic. Since VB Apps in WinForms are based on the

Application Framework runtime, there are a few features, which aren’t

intrinsically available to C# WinForms apps to begin with, like configuring to

automatically show Splash dialogs (see below) or ensure a single instance

application start. Since you configure most of the parts of your app

interactively in VB with the settings described above at design time, the actual

code which honors or ensures those settings later at runtime is mostly

code-generated and somewhat hidden behind the scenes. The starting point of a VB

app is therefore not so obvious. There are also a series of differences in .NET

Visual Basic apps when it comes to hooking up event code which is supposed to

run, for example when a VB WinForms app starts, ends, or runs into an unhandled

exception – just to name a few examples.

That all said, technically Visual Basic doesn’t break any fundamental rules.

Under the hood, there is of course a

Code:

Shared Sub Main

when you activate the

Application Framework. You just do not write it yourself, and you don’t see it,

because it is generated by the VB compiler and then automatically added to your

Start Form. This is done by activating the VB compiler switch

Code:

/main

.

At the same time, when you are activating the Application Framework, a series of

conditional compiler constants are defined. One of the constants is called

Code:

_mytype

. If that constant is defined as

Code:

Windows

then the VB compiler

generates all the necessary infrastructure code to support the Application

Framework. If that constant is defined as

Code:

WindowsFormsWithCustomSubMain

however, the VB compiler just generates the bare minimum infrastructure code and

doesn’t apply any settings to the WinForms app on startup. The latter happens,

when you deactivate the Application Framework. This setting is stored in the

vbproj project file, along with the Start Form. What’s important to know

though in this context: only in the case of

Code:

WindowsFormsWithCustomSubMain

, so

with the Application Framework deactivated, is the Start Form definition

actually taken from the vbproj file. When the Application Framework is

activated however then that is the case when the aforementioned

Application.myapp file is used as the settings container. Note, that by

default you cannot find that file in the solution explorer.

You need to make sure first to show all files for that project (see screenshot

above). Then you can open the My Project-folder and show that setting file in

the editor by double-clicking it in the solution explorer. The content of that

file looks something like this:

Code:

<?xml version="1.0" encoding="utf-16"?> <MyApplicationData xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema"> <MySubMain>true</MySubMain> <MainForm>Form1</MainForm> <SingleInstance>false</SingleInstance> <ShutdownMode>0</ShutdownMode> <EnableVisualStyles>true</EnableVisualStyles> <AuthenticationMode>0</AuthenticationMode> <SaveMySettingsOnExit>true</SaveMySettingsOnExit> <HighDpiMode>3</HighDpiMode> </MyApplicationData>

Note: Visual Studio 2022 before version 17.6 (Preview 3) won’t have the

option to pick a Splash Dialog interactively, as mentioned above. We will have

an interactive designer for setting the splash form only from that version on

on. Up to then, you can manually patch the Application.myapp file to trigger

the code generation for the Splash dialog. Insert the following line of code in

that file and save the changes.

Code:

<SplashScreen>SplashDialog</SplashScreen>

When you do this, make sure not to include the filename extension (.vb) in

that definition, because otherwise the required code does not get generated.

Application.myapp as the source for code generation

Now, if you take a closer look at that file’s properties in the property

browser, you’ll see that it is triggering a custom tool which is invoked

whenever that file is saved.

And that custom tool generates VB code which you

can find under the Application.myapp node in the Solution Explorer in

Application.Designer.vb. It does the following:

• It defines a
  Code:

  Friend Partial Class MyApplication
  . With the Application
  
  Framework enabled, that class is inherited from
  
  
  Code:

  WindowsFormsApplicationBase
  .
  
  You don’t see that
  Code:

  Inherits
  statement here and the reason is that the major
  
  part of that Class’
  
  definition
  
  is injected by the Visual Basic compiler based on the earlier defined
  
  conditional constant
  Code:

  _myapp
  .
  
  
• It generates the code to apply all the settings which were saved in
  
  Application.myapp file.
  
  
• It creates code for a method which overrides
  
  
  Code:

  OnCreateMainForm
  .
  
  In that method, it assigns the Form, which is defined as the start form in the
  
  Application.myapp file.
  

Warning: The Application.Designer.vb is not supposed to be edited, as it’s

auto-generated. Any changes will be lost as soon as you make changes to Application.myapp. Instead, use the project properties UI.

Now, the class which is injected by the compiler is also responsible for

generating everything which the Visual Basic Application Framework provides you

via the

Code:

My

namespace. The

Code:

My

namespace simplifies access to frequently used

information about your WinForms app, your system, or simplifies access to

frequently used APIs. Part of the

Code:

My

namespace for an activated Application

Framework is the

Code:

Application

property, and its return type is of exactly that

type which is defined by the class generated based on your Application Settings

and then merged with the injected Visual Basic compiler file mentioned earlier.

So, if you access

Code:

My.Application

you are basically accessing a single instance

of the

Code:

My.MyApplication

type which the generated code defines.

With this context understood, we can move on to how two additional features of

the Application Framework work and can be approached. The first one is extending

the

Code:

My

namespace with additional function areas. We won’t go too much into

them, because there are detailed docs about the

Code:

My

namespace and how to

extend

it.

An even more important concept to understand are the Application Events which are

provided by the Application Framework. Since there isn’t a good way to intercept

the startup or shut down of an app (since that code gets generated

and sort of hidden inside the main Form) Application Events are the way to be

notified of certain application-global occurrences.

Note in this context, that there is a small breaking change in the UI: while in

.NET Framework, you had to insert a code file named ApplicationEvents.vb via

the Property Settings of the VB project, in a .NET Core App this file will be

there from the start when you’ve created a new Application Framework project.

To wire up the available Application events, you open that ApplicationEvent.vb

code file, and then you select ApplicationEvents from the Object drop-down list,

and the application event you want to write up from the events list:

As you can see, the ApplicationEvent.vb code file again extends the

Code:

MyApplication

class – this time by the events handler you place there on demand. The options you have here are:

• Code:

  Startup
  : raised when the application starts, before the start form is created.
  
  
• Code:

  Shutdown
  : raised after all application forms are closed. This event is not raised if the application terminates abnormally.
  
  
• Code:

  UnhandledException
  : raised if the application encounters an unhandled exception.
  
  
• Code:

  StartupNextInstance
  : raised when launching a single-instance application and the application is already active.
  
  
• Code:

  NetworkAvailabilityChanged
  : raised when the network connection is connected or disconnected.
  
  
• Code:

  ApplyApplicationDefaults
  : raised when the application queries default values to be set for the application.
  

Note: More general information about the Visual Basic Application Model is provided through the Microsoft Learn Docs about this topic. Also note, that, on top of the extensibility of the

Code:

My

namespace, this Application Model also has extensibility points which are also described in great detail by the respective docs.

Summary

With the new and modernized project properties pages, WinForm’s Application

Framework is ready for new, .NET 6,7,8+ based Visual Basic Apps to develop. It’s

also the right time to think about modernizing your older .NET Framework based

VB Apps and bring them over to .NET 6,7,8+. WinForms and the .NET runtime

deliver countless new features and provide considerable performance improvements

for your apps in almost every area. Visual Basic and the Visual Basic

Application Framework are and continue to be first class citizens and are fully

supported in WinForms. Our plans are to continue modernizing around the VB App

Framework in the future without breaking code for existing projects.

And, as always: Feedback about the subject matter is really important to us, so

please let us know your thoughts and additional ideas! Please also note that the

WinForms .NET and the Visual Basic Application Framework runtime is open source,

and you can contribute! If you have general feature ideas, encountered bugs, or

even want to take on existing issues around the WinForms runtime and submit PRs,

have a look at the WinForms Github repo.

If you have suggestions around the WinForms Designer feel free to file new

issues there as well.

Happy coding!