i want help with a custom combobox, i found combobox on github but its custom item and i made this my own custom item and changed some preferences but i cant change background color its still white i tried everything i think. Im changed stacklayout to frame and added somethings.

Image

source code: https://github.com/Inspirare-LLC/Xamarin.Forms.ComboBox

my customized custom Item:

public class ComboBox : Frame
{
    private StackLayout _stackLayout;
    private Entry _entry;
    private ListView _listView;
    private bool _supressFiltering;
    private bool _supressSelectedItemFiltering;

    //Bindable properties
    public static readonly BindableProperty ItemsSourceProperty = BindableProperty.Create(nameof(ItemsSource), typeof(IEnumerable), typeof(ComboBox), defaultValue: null, propertyChanged: (bindable, oldVal, newVal) =>
    {
        var comboBox = (ComboBox)bindable;
        comboBox._listView.ItemsSource = (IEnumerable)newVal;
    });

    public IEnumerable ItemsSource
    {
        get { return (IEnumerable)GetValue(ItemsSourceProperty); }
        set { SetValue(ItemsSourceProperty, value); }
    }

    public static readonly BindableProperty SelectedItemProperty = BindableProperty.Create(nameof(SelectedItem), typeof(object), typeof(ComboBox), defaultValue: null, propertyChanged: (bindable, oldVal, newVal) =>
    {
        var comboBox = (ComboBox)bindable;
        comboBox._listView.SelectedItem = newVal;
    });

    public object SelectedItem
    {
        get { return (object)GetValue(SelectedItemProperty); }
        set { SetValue(SelectedItemProperty, value); }
    }

    public static new readonly BindableProperty VisualProperty = BindableProperty.Create(nameof(Visual), typeof(IVisual), typeof(ComboBox), defaultValue: new DefaultVisual(), propertyChanged: (bindable, oldVal, newVal) =>
    {
        var comboBox = (ComboBox)bindable;
        comboBox._listView.Visual = (IVisual)newVal;
        comboBox._entry.Visual = (IVisual)newVal;
    });

    public new IVisual Visual
    {
        get { return (IVisual)GetValue(VisualProperty); }
        set { SetValue(VisualProperty, value); }
    }

    public static readonly BindableProperty PlaceholderProperty = BindableProperty.Create(nameof(Placeholder), typeof(string), typeof(ComboBox), defaultValue: "", propertyChanged: (bindable, oldVal, newVal) =>
    {
        var comboBox = (ComboBox)bindable;
        comboBox._entry.Placeholder = (string)newVal;
    });

    public string Placeholder
    {
        get { return (string)GetValue(PlaceholderProperty); }
        set { SetValue(PlaceholderProperty, value); }
    }

    public static readonly BindableProperty TextProperty = BindableProperty.Create(nameof(Text), typeof(string), typeof(ComboBox), defaultValue: "", propertyChanged: (bindable, oldVal, newVal) =>
    {
        var comboBox = (ComboBox)bindable;
        comboBox._entry.Text = (string)newVal;
    });

    public string Text
    {
        get { return (string)GetValue(TextProperty); }
        set { SetValue(TextProperty, value); }
    }

    public static readonly BindableProperty ItemTemplateProperty = BindableProperty.Create(nameof(ItemTemplate), typeof(DataTemplate), typeof(ComboBox), defaultValue: null, propertyChanged: (bindable, oldVal, newVal) =>
    {
        var comboBox = (ComboBox)bindable;
        comboBox._listView.ItemTemplate = (DataTemplate)newVal;
    });

    public DataTemplate ItemTemplate
    {
        get { return (DataTemplate)GetValue(ItemTemplateProperty); }
        set { SetValue(ItemTemplateProperty, value); }
    }

    public static readonly BindableProperty EntryDisplayPathProperty = BindableProperty.Create(nameof(EntryDisplayPath), typeof(string), typeof(ComboBox), defaultValue: "");

    public string EntryDisplayPath
    {
        get { return (string)GetValue(EntryDisplayPathProperty); }
        set { SetValue(EntryDisplayPathProperty, value); }
    }

    public event EventHandler<SelectedItemChangedEventArgs> SelectedItemChanged;

    protected virtual void OnSelectedItemChanged(SelectedItemChangedEventArgs e)
    {
        EventHandler<SelectedItemChangedEventArgs> handler = SelectedItemChanged;
        handler?.Invoke(this, e);
    }

    public event EventHandler<TextChangedEventArgs> TextChanged;

    protected virtual void OnTextChanged(TextChangedEventArgs e)
    {
        EventHandler<TextChangedEventArgs> handler = TextChanged;
        handler?.Invoke(this, e);
    }


    public ComboBox()
    {
        //Entry used for filtering list view
        _entry = new Entry();
        _stackLayout = new StackLayout();
        _entry.Margin = new Thickness(0);
        _entry.Keyboard = Keyboard.Create(KeyboardFlags.None);
        _entry.Focused  = (sender, args) => _listView.IsVisible = true;
        _entry.Unfocused  = (sender, args) => _listView.IsVisible = false;


        //Text changed event, bring it back to the surface
        _entry.TextChanged  = (sender, args) =>
        {
            if (_supressFiltering)
                return;

            if (String.IsNullOrEmpty(args.NewTextValue))
            {
                _supressSelectedItemFiltering = true;
                _listView.SelectedItem = null;
                _supressSelectedItemFiltering = false;
            }

            _listView.IsVisible = true;

            OnTextChanged(args);
        };

        //List view - used to display search options
        _listView = new ListView();
        _listView.Margin = new Thickness(0);
        Xamarin.Forms.PlatformConfiguration.iOSSpecific.ListView.SetSeparatorStyle(_listView, Xamarin.Forms.PlatformConfiguration.iOSSpecific.SeparatorStyle.FullWidth);
        _listView.HeightRequest = 120;
        _listView.HorizontalOptions = LayoutOptions.StartAndExpand;
        _listView.IsVisible = false;
        _listView.SetBinding(ListView.SelectedItemProperty, new Binding(nameof(ComboBox.SelectedItem), source: this));

        //Item selected event, surface it back to the top
        _listView.ItemSelected  = (sender, args) =>
        {
            if (!_supressSelectedItemFiltering)
            {
                _supressFiltering = true;

                var selectedItem = args.SelectedItem;
                _entry.Text = !String.IsNullOrEmpty(EntryDisplayPath) && selectedItem != null ? selectedItem.GetType().GetProperty(EntryDisplayPath).GetValue(selectedItem, null).ToString() : selectedItem?.ToString();

                _supressFiltering = false;
                _listView.IsVisible = false;
                OnSelectedItemChanged(args);
            }
        };

        //Add bottom border
        var boxView = new BoxView();
        boxView.HeightRequest = 1;
        boxView.Color = Color.FromHex(AppThemeColors._borderColor);
        boxView.Margin = new Thickness(0);
        boxView.SetBinding(BoxView.IsVisibleProperty, new Binding(nameof(ListView.IsVisible), source: _listView));

        //Custom preferences
        _stackLayout.BackgroundColor = Color.Transparent;
        _entry.BackgroundColor = Color.Transparent;
        _listView.BackgroundColor = Color.Transparent;
        _entry.PlaceholderColor = Color.Red; 

        //Add main view
        _stackLayout.Margin = new Thickness(-10);
        _stackLayout.Children.Add(_entry);
        _stackLayout.Children.Add(_listView);
        _stackLayout.Children.Add(boxView);
        Content = _stackLayout;
    }

    public new bool Focus()
    {
        return _entry.Focus();
    }

    public new void Unfocus()
    {
        _entry.Unfocus();
    }
}

CodePudding user response：

Github using; Visual property is on material but its making background color to white and cant change need set visual property to default.

                         <cb:ComboBox

                            //Changed visual to default 
                            //github usage is Visual = "Material"

                            Visual="Default">
                            <cb:ComboBox.ItemTemplate>
                                <DataTemplate>
                                    <ViewCell>

                                    </ViewCell>
                                </DataTemplate>
                            </cb:ComboBox.ItemTemplate>
                        </cb:ComboBox>