从另一个用户控件（登录）更改WPF用户控件的可见性

Question

I created an application with WPF and C# (no MVVM), I have multiple user controls containing grids, forms and others things. but finaly I wanted to add a login page, the way I started to build it, is to set by default all the user controls visibility in xaml to collapsed :

 Visibility="Collapsed"

and for the login user control to visible, and after login and in the C# code behind I want to change the visibility of other usercontrols to visible and set the login page to collapsed.

I've tried something like this, but it didn't work :

  Students studentsWin = new Students(); 
  studentsWin.Visibility = Visibility.Visible;

  Members MembersWin = new Members();
  MembersWin.Visibility = Visibility.Visible;

I have read in stackoverflow to use dependency proprety, and since I never used MVVM I don't know how to use it : I'm trying something like this :

    public static DependencyProperty WindowVisibilityProperty = DependencyProperty.Register("WindowVisibility", typeof(Visibility), typeof(MemberStats), null);

    public Visibility WindowVisibility
    {
        get
        {
            return (Visibility)GetValue(WindowVisibilityProperty);
        }
        set
        {
            SetValue(WindowVisibilityProperty, value);
        }
    }

But I don't know how to use WindowVisibility in the xaml of the user controls, any help would be appreciated .

Answer 1

1. Simple approach. Use the following layout

    <Grid> <Grid x:Name="UC_Container"> <!-- Rest of user controls go here --> </Grid> <uc:UserControl1 x:Name="LoginUC" Background="Aqua"/> </Grid> 

Hide the LogiUI itself in it's say SignIn button:click, like

this.Visibility = Visibility.Collapsed

Your login-ui will be hidden and the grid lying below containing your rest of uc will be visible.

2. The approach which you are thinking : You need a dependency property like ShowLoginUI in your Login UC.Then after user Signin successfully simply set it to false, as LoginUI is no longer needed.

Then in your MainWindow where you are using all the controls, bind login-ui container Grid's visibility to your LoginUI's ShowLoginUI dep-property.

No need to set visibility of UC_Container as it will be hidden by LoginUI as we are using a Grid.

LoginControl might look like :

    public partial class LoginUC : UserControl
        {
            public bool ShowLoginUI
            {
                get { return (bool)GetValue(ShowLoginUIProperty); }
                set { SetValue(ShowLoginUIProperty, value); }
            }

            public static readonly DependencyProperty ShowLoginUIProperty =
                DependencyProperty.Register("ShowLoginUI", typeof(bool), typeof(UserControl1), new PropertyMetadata(true)); 

            ...

            private void SignIn_Click(object sender, RoutedEventArgs e)
            {
               // check login credentials
               // if success
               ShowLoginUI = false;
            }
       }

Have one panel to hold your user-controls and another panel for login UI. Use Grid as top container as it allows it's children to stack on top of each other hiding those below. BooleanToVisibilityConverter is the in-built converter class which you can use.

<Window.Resources>
        <BooleanToVisibilityConverter x:Key="ConvBoolToVis" />
    </Window.Resources>
<Grid>
  <Grid x:Name="UC_Container">
       <!-- Rest of user controls go here -->
  </Grid>
  <Grid x:Name="LoginUI_Container" Visibility="{Binding ShowLoginUI, ElementName=LoginUC, Converter={StaticResource ConvBoolToVis}}">
        <uc:UserControl1 x:Name="LoginUC" Background="Aqua"/>
    </Grid>
</Grid>

3. Best approach would be to use Frames. Frames cleanly separate your Login-UI and rest of UCs.

Frames in WPF

Answer 2

Students studentsWin = new MembresList(); //Students is the user control name >studentsWin.Visibility = Visibility.Visible;

Members MembersWin = new AjouterMembre();//Members is the user control name >MembersWin.Visibility = Visibility.Visible;

If "Students" is the user control name (meaning you added x:Name="Students" to the control in the XAML) then you will be able to access it in the code behind with the line :

Students.visibility = Visibility.Visible;

I'm going to explore the rest of your code below, in hopes that it will help you. If you're pretty new to C# and WPF, I hope the following doesn't discourage you by making things seem overly complicated.

Does "Students studentsWin = new MembresList();" compile? MembresList would have to be a subclass of a Students class, which would be an odd class hierarchy. But even if that line did compile, the line after that would definitely not compile. "Students" would have to be the name of the class, but Visibility is an instance property of UI objects. If Students was a subclass of UserControl, you could do

Students myStudent = new Student(); //Assumes Students subclasses Usercontrol
myStudent.visibility = Visibility.Visible; //This compiles but is useless

The code above would compile, but would be useless, because the new myStudent object hasn't been added anywhere to your form. It's just an object that lives within the scope of the method that defines it.

Dependency Properties are a useful thing, but I wouldn't worry about them until you have a good handle on C# and WPF in general. That stuff is pretty advanced.