Update listview label font size on button click

nonubitta

I have a label inside a listview. I want to change font size of that label on click of a button.

Yelinzh

You could set binding to the FontSize property. Detect the button's click event, then traverse the data collection to specify a value to FontSize.

Check the code:

<ListView.ItemTemplate>
    <DataTemplate>
        <ViewCell>
            <StackLayout>
                <Label Text="{Binding Content}" FontSize="{Binding Size}"/>
            </StackLayout>
        </ViewCell>
    </DataTemplate>
</ListView.ItemTemplate>

Page.xaml.cs

public partial class Page1 : ContentPage
{
    ObservableCollection<Model_Class> models = new ObservableCollection<Model_Class>();
    public Page1()
    {
        InitializeComponent();

        //add the data

        listview.ItemsSource = models;
    }

    private void Button_Clicked(object sender, EventArgs e)
    {
        foreach (var item in models)
        {
            item.Size = 24;
        }
    }
}

Model class

public class Model_Class : INotifyPropertyChanged
{
    private int size;
    public int Size
    {
        get
        {
            return size;
        }
        set
        {
            if (size != value)
            {
                size = value;
                NotifyPropertyChanged();
            }
        }
    }
    ...
    protected virtual void NotifyPropertyChanged([CallerMemberName] string propertyName = "")
    {
        PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
    }

    public event PropertyChangedEventHandler PropertyChanged;
}

Yelinzh

You could set binding to the FontSize property. Detect the button's click event, then traverse the data collection to specify a value to FontSize.

Check the code:

<ListView.ItemTemplate>
    <DataTemplate>
        <ViewCell>
            <StackLayout>
                <Label Text="{Binding Content}" FontSize="{Binding Size}"/>
            </StackLayout>
        </ViewCell>
    </DataTemplate>
</ListView.ItemTemplate>

Page.xaml.cs

public partial class Page1 : ContentPage
{
    ObservableCollection<Model_Class> models = new ObservableCollection<Model_Class>();
    public Page1()
    {
        InitializeComponent();

        //add the data

        listview.ItemsSource = models;
    }

    private void Button_Clicked(object sender, EventArgs e)
    {
        foreach (var item in models)
        {
            item.Size = 24;
        }
    }
}

Model class

public class Model_Class : INotifyPropertyChanged
{
    private int size;
    public int Size
    {
        get
        {
            return size;
        }
        set
        {
            if (size != value)
            {
                size = value;
                NotifyPropertyChanged();
            }
        }
    }
    ...
    protected virtual void NotifyPropertyChanged([CallerMemberName] string propertyName = "")
    {
        PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
    }

    public event PropertyChangedEventHandler PropertyChanged;
}