I have a problem in slider value data binding in MVVM. When value gets changed my expected value isn’t achieved. How can I solve my problem?
I have a listbox, a slider and a textblock. listbox is bound to ListImage, slider value and textblock text is bound to CurrentImage. One button with command navigate the lisbox item. CurrentImage is a property in the viewmodel. When I change slider’s setter, new value of setter put to current value of slider’s setter and the arrangement of listbox gets corrupted. For example when value of my slider’s setter set to 50 and I change value of slider to 10 again. My slider value navigate from 10 to 50 and not more. It must be navigate whole of the listbox but it can’t. There is my code:
XAML:
<TextBlock Text="{Binding CurrentImage.Index}"/>
<Slider Height="23" HorizontalAlignment="Left" Margin="12,305,0,0" Name="slider1" VerticalAlignment="Top" Width="479" Maximum="{Binding ListImage.Count, Mode=OneTime}"
Value="{Binding CurrentImage.Index, Mode=TwoWay}"
SmallChange="1" />
<Button Content="{Binding DisplayPlay}" Command="{Binding PlayCommand}" Height="23" HorizontalAlignment="Left" Margin="507,305,0,0" Name="button1" VerticalAlignment="Top" Width="75" />
<ListBox Height="129" HorizontalAlignment="Left" Margin="12,334,0,0" ItemsSource="{Binding ListImage}" SelectedItem="{Binding CurrentImage,Mode=TwoWay}"
VerticalAlignment="Top" Width="472">
viewmodel:
public class MainViewModel : ViewModelBase
{
public ICommand PlayCommand { get; set; }
private DispatcherTimer _Timer;
public ImageDTO Image { get; set;}
DataAccess AC = new DataAccess();
public byte[] Bytes { get; set; }
public MainViewModel()
{
ListImage = AC.OpenImages();
CurrentImage = ListImage[0];
Bytes = CurrentImage.Bytes;
this.PlayCommand = new DelegateCommand(Play, CanPlay);
DisplayPlay = "Play";
_Timer = new DispatcherTimer();
_Timer.Interval = new TimeSpan(0, 0, 0, 0, 2000 / 30);
_Timer.Tick += new EventHandler(timer_Tick);
}
private string _DisplayPlay;
public string DisplayPlay
{
get { return _DisplayPlay; }
set
{
if (_DisplayPlay != value)
{
_DisplayPlay = value;
OnPropertyChanged("DisplayPlay");
}
}
}
private List<ImageDTO> _ListImage;
public List<ImageDTO> ListImage
{
get { return _ListImage; }
set
{
if (_ListImage != value)
_ListImage = value;
OnPropertyChanged("ListImage");
}
}
private ImageDTO _CurrentImage;
public ImageDTO CurrentImage
{
get { return _CurrentImage; }
set
{
if (_CurrentImage != value)
{
_CurrentImage = value;
OnPropertyChanged("CurrentImage");
}
}
}
public bool CanPlay(object parameter)
{
return true;
}
public void Play(object parameter)
{
if (DisplayPlay == "Play")
{
DisplayPlay = "Pause";
_Timer.Start();
}
else
{
_Timer.Stop();
DisplayPlay = "Play";
}
}
private void timer_Tick(object sender, EventArgs e)
{
int position = ListImage.FindIndex(x => x.Index == CurrentImage.Index);
position++;
if (position == ListImage.Count)
{
position = 0;
}
else
{
CurrentImage = ListImage[position];
}
}