BnPicker
Namespace: BlazorNative.Components
A drop-down / wheel picker over a list of strings. Renders as
BnSpinner on Android, a Spinner subclass, and as
UIPickerView on iOS.
public class BnPicker : BnLayoutItem, Microsoft.AspNetCore.Components.IComponent, Microsoft.AspNetCore.Components.IHandleEvent, Microsoft.AspNetCore.Components.IHandleAfterRender, BlazorNative.Core.IForwardsUiEvent
Inheritance Object → ComponentBase → BnLayoutItem → BnPicker
Implements IComponent, IHandleEvent, IHandleAfterRender, IForwardsUiEvent
Remarks:
Unlike BnInput — where the text lives in your code and the widget echoes it — a native picker owns its selection UI, so the whole item list is handed to the platform and the selection comes back as an index.
The selection is always valid, and the picker will correct you. With no
items the index is -1. With items, it is clamped into range: a negative
becomes 0, and an index past the end becomes the last item — because a
native picker always shows something, so "nothing selected" is not a state it
can represent. When clamping moves the value, SelectedIndexChanged
fires with the clamped index, so your bound state re-syncs to what is actually
on screen instead of the two quietly disagreeing.
<BnPicker Items="_cities" @bind-SelectedIndex="_city" />
@code {
private readonly string[] _cities = ["Amsterdam", "Rotterdam", "Utrecht"];
private int _city;
}
Properties
Items
The strings to show. Null or empty means an empty picker. The text is opaque — commas, quotes and non-ASCII are all fine.
public IReadOnlyList<string>? Items { get; set; }
Property Value
SelectedIndex
The selected index. It is always clamped to something valid
before it reaches the platform: -1 when BnPicker.Items is
empty, otherwise into [0, Count-1]. When the clamp moves it,
BnPicker.SelectedIndexChanged fires with the clamped value so your
bound state matches what is on screen.
public int SelectedIndex { get; set; }
Property Value
SelectedIndexChanged
Raised with the newly selected index when the user picks — the
write-back half of the @bind-SelectedIndex pair. It is also
raised with the clamped index when a change to BnPicker.Items forces
one, so your bound state never drifts from what the picker shows.
public EventCallback<int> SelectedIndexChanged { get; set; }
Property Value
Enabled
Set false to show the platform's disabled picker and stop it responding. Default true.
public bool Enabled { get; set; }
Property Value
BackgroundColor
Fill colour behind the component. Null leaves it transparent.
public string? BackgroundColor { get; set; }
Property Value
Margin
Space outside the component, between it and its siblings. Null = none.
public BnAutoLength? Margin { get; set; }
Property Value
Remarks:
auto is legal here and absorbs free space, which re-centres the node.
AlignSelf
Cross-axis alignment for this item alone, overriding the parent's. Null = inherit.
public FlexAlign? AlignSelf { get; set; }
Property Value
Grow
Share of leftover space this item takes (unitless ratio). Null = Yoga's default (0).
public float? Grow { get; set; }
Property Value
Shrink
Share of overflow this item gives up (unitless ratio). Null = Yoga's default (1).
public float? Shrink { get; set; }
Property Value
Basis
Starting main-axis size before grow/shrink. Null = auto.
public BnAutoLength? Basis { get; set; }
Property Value
Width
Box width. Null = auto.
public BnAutoLength? Width { get; set; }
Property Value
Height
Box height. Null = auto.
public BnAutoLength? Height { get; set; }
Property Value
MinWidth
Lower bound on width. Null = unset.
public BnLength? MinWidth { get; set; }
Property Value
MaxWidth
Upper bound on width. Null = unset.
public BnLength? MaxWidth { get; set; }
Property Value
MinHeight
Lower bound on height. Null = unset.
public BnLength? MinHeight { get; set; }
Property Value
MaxHeight
Upper bound on height. Null = unset.
public BnLength? MaxHeight { get; set; }
Property Value
Position
Positioning scheme. Null = Yoga's default (relative).
public FlexPosition? Position { get; set; }
Property Value
Top
Top inset. Null = unset.
public BnLength? Top { get; set; }
Property Value
Right
Right inset. Null = unset.
public BnLength? Right { get; set; }
Property Value
Bottom
Bottom inset. Null = unset.
public BnLength? Bottom { get; set; }
Property Value
Left
Left inset. Null = unset.
public BnLength? Left { get; set; }
Property Value
Constructors
BnPicker()
public BnPicker()