WPF Discussion Boards

Re: WPF .Net Core 6 RelayCommand Problem

3-Feb-23 12:33

I'm trying to create a simple log in window. The Sign In button does not get enabled. The CanExecuteChange fires on startup, but never after that.

You can see that I'm using the Community Toolkit. I've also tried the RelayCommand in my own framework. Neither work. I have also tried

CommandManager.InvalidateRequerySuggested();

in the UserName and Password properties.

Here's the Sign In button

<Button Grid.Row="7"
        Grid.Column="0"
        Content="Sign In"
        Command="{Binding SignInCommand}"
        Margin="0,0,0,0"/>

Here's the View Model

using CommunityToolkit.Mvvm.Input;
using Marois.Framework.Core.Shared;
using System.Windows.Input;

namespace Jayhawk.UI.WPF.ViewModels
{
    public class LoginViewModel : _DialogViewModelBase
    {
        #region Private Fields
        private readonly IEventAggregator _eventAggregator;
        #endregion

        #region Properties
        private string? _UserName;
        public string? UserName
        {
            get { return _UserName; }
            set
            {
                SetProperty(nameof(UserName), ref _UserName, value);
            }
        }

        private string? _Password;
        public string? Password
        {
            get { return _Password; }
            set
            {
                SetProperty(nameof(Password), ref _Password, value);
            }
        }

        private bool _IsRememberMeChecked;
        public bool IsRememberMeChecked
        {
            get { return _IsRememberMeChecked; }
            set
            {
                SetProperty(nameof(IsRememberMeChecked), ref _IsRememberMeChecked, value);
            }
        }

        private bool _IsLoggingIn;
        public bool IsLoggingIn
        {
            get { return _IsLoggingIn; }
            set
            {
                SetProperty(nameof(IsLoggingIn), ref _IsLoggingIn, value);
            }
        }
        #endregion

        #region Commands
        private ICommand? _SignInCommand;
        public ICommand? SignInCommand
        {
            get
            {
                if (_SignInCommand == null)
                    _SignInCommand = new RelayCommand(SignInExecuted, SignInCanExecute);
                return _SignInCommand;
            }
        }
        #endregion

        #region CTOR
        public LoginViewModel()
        {
        }
        #endregion

        #region Private Methods
        private bool SignInCanExecute()
        {
            return !string.IsNullOrEmpty(UserName) && !string.IsNullOrEmpty(Password);
        }

        private void SignInExecuted()
        {
            IsLoggingIn = true;

            // TODO: Do the log in
        }
        #endregion
    }
}

If it's not broken, fix it until it is.
Everything makes sense in someone's mind.
Ya can't fix stupid.

Richard Deeming5-Feb-23 23:18

Richard Deeming

5-Feb-23 23:18

Looking at the source code for CommunityToolkit.Mvvm.Input.RelayCommand[^], it doesn't use the CommandManager at all. You need to explicitly call the NotifyCanExecuteChanged method[^] instead.

NB: That SetProperty method looks odd - any relatively recent framework would use [CallerMemberName] so that you don't need to pass the name of the property:

protected bool SetProperty<T>(ref T storage, T value, [CallerMemberName] string propertyName = null)
{
    if (Equals(storage, value)) return false;
    
    storage = value;
    OnPropertyChanged(propertyName);
    return true;
}

public string? UserName
{
    get { return _UserName; }
    set { SetProperty(ref _UserName, value); }
}

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how to set the icon for output result(.exe) in vs2022 ?

Member 136170031-Feb-23 14:56

Member 13617003

1-Feb-23 14:56

hi guys, how to set the icon for output result(.exe) in vs2022 ? thanks.

Re: how to set the icon for output result(.exe) in vs2022 ?

Richard MacCutchan1-Feb-23 21:12

Richard MacCutchan

1-Feb-23 21:12

Try Project -> Properties.

Re: how to set the icon for output result(.exe) in vs2022 ?

Member 136170032-Feb-23 13:43

Member 13617003

2-Feb-23 13:43

Got it, thanks a lot.

Expander Width Problem

Kevin Marois13-Jan-23 13:01

Re: Expander Width Problem

13-Jan-23 13:01

I'm trying to create a ListBox, with it's ItemTemplate being an expander, which itself has a list in it.

Here's a pic of what I'm trying to accomplish. Pic
I added colors around each item to highlight what's happening.

Here's the XAML

<ListBox Grid.Row="2"
            Grid.Column="1"
            x:Name="outerList"
            Margin="2,2,2,2"
            Background="Transparent"
            ItemsSource="{Binding RecentItemSections}"
            SelectedItem="{Binding SelectedRecentItemSection}"
            HorizontalAlignment="Stretch"
            BorderBrush="Yellow"
            BorderThickness="2">

    <ListBox.ItemTemplate>

        <DataTemplate>

            <Expander IsExpanded="{Binding IsSectionExpanded}"
                        x:Name="expander"
                        HorizontalAlignment="Stretch"
                        BorderBrush="Red"
                        BorderThickness="2">

                <Expander.Header>
                    <TextBlock Text="{Binding SectionName}"
                                Foreground="White" 
                                Width="{Binding RelativeSource={RelativeSource Mode=FindAncestor,
                                    AncestorType={x:Type ListBoxItem}}, Path=ActualWidth}"/>
                </Expander.Header>

                <ListBox ItemsSource="{Binding RecentItems}"
                            BorderBrush="Green"
                            BorderThickness="5"
                            Margin="2,0,20,0">

                    <ListBox.ItemTemplate>
                        <DataTemplate>

                            <Border BorderBrush="MediumAquamarine"
                                    BorderThickness="2">

                                <StackPanel Orientation="Vertical"
                                        HorizontalAlignment="Stretch">

                                    <TextBlock Text="{Binding ItemName}"
                                            FontSize="12"
                                            Margin="2"/>

                                    <TextBlock Text="{Binding ItemLocation}"
                                            FontSize="10"
                                            Margin="2,0,2,2"/>

                                </StackPanel>

                            </Border>

                        </DataTemplate>
                    </ListBox.ItemTemplate>

                </ListBox>

            </Expander>

        </DataTemplate>

    </ListBox.ItemTemplate>

</ListBox>

As you can see in the pic, the Expander's header is off the right side of the listbox item.

How can I get the expander to fit inside its parent, the ListBox?

If it's not broken, fix it until it is.
Everything makes sense in someone's mind.
Ya can't fix stupid.

Gerry Schmitz14-Jan-23 5:43

14-Jan-23 5:43

You should know what the maximum header width will be; set the .Width accordingly. (The framework doesn't know beforehand).

"Before entering on an understanding, I have meditated for a long time, and have foreseen what might happen. It is not genius which reveals to me suddenly, secretly, what I have to say or to do in a circumstance unexpected by other people; it is reflection, it is meditation." - Napoleon I

TabItem Render

Kevin Marois9-Jan-23 18:59

9-Jan-23 18:59

I'd like to load a TabItems's content async.

What would be nice is to see the Tab Item added to the TabControl, then do the async load while a spinning indicator is running.

Something like ContentRendered would do, but I don't see anything like it on the TabItem.

Anyone know of a way to do this?

If it's not broken, fix it until it is.
Everything makes sense in someone's mind.
Ya can't fix stupid.

Advanced TypeScript Programming Projects

Pete O'Hanlon9-Jan-23 19:38

Pete O'Hanlon

9-Jan-23 19:38

When I do this type of thing, I use MVVM and have a state represent the loaded nature; the visibility of the spinner animation is bound to the loaded state.

Kevin Marois9-Jan-23 20:07

9-Jan-23 20:07

Let me clarify my question... I'm not asking about the indicator...

Tab appears.
Spinning indicator appears
Call GetData
Data is returned
Tab's content is loaded
Indicator goes away.

The problem is that I want to show a blank tab first, then start the process of getting the data. But where do you start it from? There doesn't seem to be a ContentRedered or Loaded or Initialized event to kick off the async data call after the tab is visible

If it's not broken, fix it until it is.
Everything makes sense in someone's mind.
Ya can't fix stupid.

Advanced TypeScript Programming Projects

Pete O'Hanlon9-Jan-23 20:38

Pete O'Hanlon

9-Jan-23 20:38

I can't tell whether you are using MVVM or not from your question. If I were doing this, I would adopt a slightly different approach; I would bind the tabs to an ObservableCollection. When I instantiate my new tab and add it to the collection, I would trigger the async load. In other words, I disconnect the state from the visual. I don't need to worry about tracking tab states because this is automatically connected to my ViewModel.

Gerry Schmitz10-Jan-23 6:45

WPF Custom Control & User Control

10-Jan-23 6:45

TabItem inherits from FrameworkElement and therefore has a "Loaded" event.

Kevin Marois30-Dec-22 18:49

30-Dec-22 18:49

When you design a CustomControl or UserControl, how do you fire off a method inside it?

Say for example you create a control that needs to load some data async. So you put the control on a Window and start the window. There's no way to call into the control and call 'Load()'.

You can bind to it, but what would you bind? You could have it listen to an event. Is there some other way?

If it's not broken, fix it until it is.
Everything makes sense in someone's mind.
Ya can't fix stupid.

modified 31-Dec-22 14:45pm.

Graeme_Grant31-Dec-22 3:18

Graeme_Grant

31-Dec-22 3:18

You can use async but you may be on a different thread to the UI when trying to update data bound to the UI. You need to marshall to the UI thread or you will get cross-thread exceptions. My previous answer where I point to a series of WPF YT videos will answer this question for you.

Graeme

"I fear not the man who has practiced ten thousand kicks one time, but I fear the man that has practiced one kick ten thousand times!" - Bruce Lee

Kevin Marois31-Dec-22 8:44

31-Dec-22 8:44

Not sure what you mean by this response.

I'm asking how to create a UserControl or CustomControl, place it on a Window, then execute a method on it from a button click on the Window.

If it's not broken, fix it until it is.
Everything makes sense in someone's mind.
Ya can't fix stupid.

Graeme_Grant31-Dec-22 10:53

Graeme_Grant

31-Dec-22 10:53

Kevin Marois wrote:
I'm asking how to create a UserControl or CustomControl, place it on a Window, then execute a method on it from a button click on the Window.

Okay, that is a lot clearer and easier to understand what you want.

I wrote an article that walks through extending a Control: Flexible WPF ToggleSwitch Lookless Control in C# & VB[^]. UserControls are just like another Window to use.

Graeme

"I fear not the man who has practiced ten thousand kicks one time, but I fear the man that has practiced one kick ten thousand times!" - Bruce Lee

Sandeep Mewara31-Dec-22 8:55

Sandeep Mewara

31-Dec-22 8:55

You expose the events for that usercontrol/custom control. Now treat them like any other standard control. Place them in your form and then define a method for the exposed events.

An example here:
Exposing Custom event from custom control
ClientCallback custom control for web applications

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Kevin Marois31-Dec-22 14:59

31-Dec-22 14:59

I'm not asking about events. I'm asking how to call the Load method on my UserControl from the Window's ViewModel. The UserControl uis a stand along control. It needs to have Load called to load up the data. The Window's ViewModel doesn't know about the UserControl.

If it's not broken, fix it until it is.
Everything makes sense in someone's mind.
Ya can't fix stupid.

Gerry Schmitz31-Dec-22 10:58

31-Dec-22 10:58

You give the user control a .Name in the XAML; the .Name is available to the Window's code behind. If you want to access the UC outside of the Window, you need to add a public reference to the UC; e.g. public Type UC => (name of UC in XAML).

In those cases where the UC is a (global) singleton, I (may) give it a public static reference to its instance; the UC can then be accessed by any part of the app in that case.

Kevin Marois31-Dec-22 14:59

31-Dec-22 14:59

There is no code behind. I'm using MVVM

If it's not broken, fix it until it is.
Everything makes sense in someone's mind.
Ya can't fix stupid.

Gerry Schmitz1-Jan-23 2:59

1-Jan-23 2:59

You could have said that at the outset: "I will only entertain MVVM solutions". Noted.

Kevin Marois1-Jan-23 14:27

1-Jan-23 14:27

Sorry for the confusion. I just asumed that MVVM is the way most folks do things.

So I found out a way to load my control:

public override void OnApplyTemplate()
{
    base.OnApplyTemplate();

    Load();
}

Not sure if this is the best way, but it works.

Thanks

If it's not broken, fix it until it is.
Everything makes sense in someone's mind.
Ya can't fix stupid.

Path Image

Kevin Marois28-Dec-22 16:27