agiro agiro - 1 month ago 10
C# Question

MVVM light Binding Path not working

I'm trying to bind a variable to show in a label's content.
I use

Galasoft's MVVM light
to achieve this.
I send my
viewmodel
, my
window
and my
window.cs
. The issue is that nothing happens when I increase the values but something should.

Window: I have binding on only one label

<Window x:Class="DPCKOU_prog3hf_pong.Settings"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:local="clr-namespace:DPCKOU_prog3hf_pong"
mc:Ignorable="d"
Title="Settings" Height="406" Width="717"
Background="{StaticResource MainMenuBG}"
ResizeMode="NoResize"
WindowStartupLocation="CenterScreen"
>
<Grid>
<StackPanel>
<Label x:Name="Title" HorizontalContentAlignment="Center" HorizontalAlignment="Stretch"
Foreground="#00e4ff" FontSize ="28" Content="Size of pad"
Margin="10,30,10,10">
<Label.BitmapEffect>
<DropShadowBitmapEffect Color="#00e4ff" ShadowDepth="0" Opacity="1"/>
</Label.BitmapEffect>
</Label>
<Label x:Name="Size" HorizontalContentAlignment="Center" HorizontalAlignment="Stretch"
Foreground="#00e4ff" FontSize ="40" Content="{Binding Path=PadSize}"
Margin="10,0,10,10">
<Label.BitmapEffect>
<DropShadowBitmapEffect Color="#00e4ff" ShadowDepth="0" Opacity="1"/>
</Label.BitmapEffect>
</Label>
<DockPanel>
<Button x:Name="Increase" Content="Increase" HorizontalAlignment="Left"
Width="149" Height="46" Foreground="#00e4ff" Background="Black" Margin="120,10,10,10"
FontSize="18" BorderThickness="0" Click="Increase_Click">
<Button.BitmapEffect>
<DropShadowBitmapEffect Color="#00e4ff" ShadowDepth="0" Opacity="1"/>
</Button.BitmapEffect>
</Button>
<Button x:Name="Decrease" Content="Decrease" HorizontalAlignment="Right"
Width="149" Height="46" Foreground="#00e4ff" Background="Black" Margin="10,10,120,10"
FontSize="18" BorderThickness="0" Click="Decrease_Click">
<Button.BitmapEffect>
<DropShadowBitmapEffect Color="#00e4ff" ShadowDepth="0" Opacity="1"/>
</Button.BitmapEffect>
</Button>
</DockPanel>
<Button x:Name="Play" Content="Play" HorizontalAlignment="Center"
Width="149" Height="46" Foreground="#00e4ff" Background="Black" Margin="10,10,10,10"
FontSize="18" BorderThickness="0" Click="Play_Click">
<Button.BitmapEffect>
<DropShadowBitmapEffect Color="#00e4ff" ShadowDepth="0" Opacity="1"/>
</Button.BitmapEffect>
</Button>
<Button x:Name="Back" Content="Back" HorizontalAlignment="Center"
Width="149" Height="46" Foreground="#00e4ff" Background="Black" Margin="10,10,10,10"
FontSize="18" BorderThickness="0" Click="Back_Click">
<Button.BitmapEffect>
<DropShadowBitmapEffect Color="#00e4ff" ShadowDepth="0" Opacity="1"/>
</Button.BitmapEffect>
</Button>
</StackPanel>
</Grid>




The model's
cs
:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using GalaSoft.MvvmLight;

namespace DPCKOU_prog3hf_pong
{
class SettingsVM : ViewModelBase
{
int padSize;
public int PadSize
{
get
{
return padSize;
}
set
{
if(value >=1 && value <= 6)
{
Set(ref padSize, value);
}
}
}
public SettingsVM()
{
padSize = 1;

}
}
}


and the
window.cs
:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Shapes;
using GalaSoft.MvvmLight;

namespace DPCKOU_prog3hf_pong
{
/// <summary>
/// Interaction logic for SingleSettings.xaml
/// </summary>
///
/*
* take it 100 pixels is the 4 units of the pad's size respectively.
* so 25 shall be 1 and that is the default value one can input.
* the player can input pad size from 1 to 6 meaning from 25 pixels to 150.
*/

public partial class Settings : Window
{
/*
* its sole purpose is to change the pad size.
*/
SettingsVM svm;
bool isPlaymodeSingle;
public Settings(bool isPlaymodeSingle)
{
InitializeComponent();
this.isPlaymodeSingle = isPlaymodeSingle;
svm = new SettingsVM();
}

private void Play_Click(object sender, RoutedEventArgs e)
{
if (isPlaymodeSingle)
{
//yes, solo
SinglePlayer spgame = new SinglePlayer();
spgame.Show();
Close();
/*
* show the game window and close this.
*/
}
else
{
//nope, multi.

}
}

private void Decrease_Click(object sender, RoutedEventArgs e)
{
svm.PadSize--;
}

private void Increase_Click(object sender, RoutedEventArgs e)
{
svm.PadSize++;
}

private void Back_Click(object sender, RoutedEventArgs e)
{
MainWindow mw = new MainWindow();
mw.Show();
Close();
}


}
}

Answer

You forgot to set the DataContext of the Window.

You can do that for example in the constructor of the Settings class:

public Settings(bool isPlaymodeSingle)
{
    InitializeComponent();
    this.isPlaymodeSingle = isPlaymodeSingle;
    svm = new SettingsVM();

    DataContext = svm; // here
}