我有一个自定义Checkbox，如下所示;
public class CheckBox : View, INotifyPropertyChanged
{
/// <summary>
/// The checked state property.
/// </summary>
public static readonly BindableProperty CheckedProperty =
BindableProperty.Create<CheckBox, bool>(
p => p.Checked, false, BindingMode.TwoWay, propertyChanged: OnCheckedPropertyChanged);
/// <summary>
/// The checked text property.
/// </summary>
public static readonly BindableProperty CheckedTextProperty =
BindableProperty.Create<CheckBox, string>(
p => p.CheckedText, string.Empty, BindingMode.TwoWay);
/// <summary>
/// The unchecked text property.
/// </summary>
public static readonly BindableProperty UncheckedTextProperty =
BindableProperty.Create<CheckBox, string>(
p => p.UncheckedText, string.Empty);
/// <summary>
/// The default text property.
/// </summary>
public static readonly BindableProperty DefaultTextProperty =
BindableProperty.Create<CheckBox, string>(
p => p.Text, string.Empty,BindingMode.TwoWay, propertyChanged: OnDefaultTextChanged);
/// <summary>
/// Identifies the TextColor bindable property.
/// </summary>
///
/// <remarks/>
public static readonly BindableProperty TextColorProperty =
BindableProperty.Create<CheckBox, Color>(
p => p.TextColor, Color.Default);
/// <summary>
/// The font size property
/// </summary>
public static readonly BindableProperty FontSizeProperty =
BindableProperty.Create<CheckBox, double>(
p => p.FontSize, -1);
/// <summary>
/// The font name property.
/// </summary>
public static readonly BindableProperty FontNameProperty =
BindableProperty.Create<CheckBox, string>(
p => p.FontName, string.Empty);
/// <summary>
/// The checked changed event.
/// </summary>
public event EventHandler<EventArgs<bool>> CheckedChanged;
public event PropertyChangedEventHandler PropertyChanged;
/// <summary>
/// Gets or sets a value indicating whether the control is checked.
/// </summary>
/// <value>The checked state.</value>
public bool Checked
{
get
{
return this.GetValue<bool>(CheckedProperty);
}
set
{
if (this.Checked != value)
{
this.SetValue(CheckedProperty, value);
this.CheckedChanged.Invoke(this, value);
}
}
}
/// <summary>
/// Gets or sets a value indicating the checked text.
/// </summary>
/// <value>The checked state.</value>
/// <remarks>
/// Overwrites the default text property if set when checkbox is checked.
/// </remarks>
public string CheckedText
{
get
{
return this.GetValue<string>(CheckedTextProperty);
}
set
{
this.SetValue(CheckedTextProperty, value);
}
}
/// <summary>
/// Gets or sets a value indicating whether the control is checked.
/// </summary>
/// <value>The checked state.</value>
/// <remarks>
/// Overwrites the default text property if set when checkbox is checked.
/// </remarks>
public string UncheckedText
{
get
{
return this.GetValue<string>(UncheckedTextProperty);
}
set
{
this.SetValue(UncheckedTextProperty, value);
}
}
/// <summary>
/// Gets or sets the text.
/// </summary>
public string DefaultText
{
get
{
return this.GetValue<string>(DefaultTextProperty);
}
set
{
this.SetValue(DefaultTextProperty, value);
NotifyPropertyChanged("DefaultTextProperty");
NotifyPropertyChanged("DefaultText");
}
}
/// <summary>
/// Gets or sets the color of the text.
/// </summary>
/// <value>The color of the text.</value>
public Color TextColor
{
get
{
return this.GetValue<Color>(TextColorProperty);
}
set
{
this.SetValue(TextColorProperty, value);
}
}
/// <summary>
/// Gets or sets the size of the font.
/// </summary>
/// <value>The size of the font.</value>
public double FontSize
{
get
{
return (double)GetValue(FontSizeProperty);
}
set
{
SetValue(FontSizeProperty, value);
}
}
/// <summary>
/// Gets or sets the name of the font.
/// </summary>
/// <value>The name of the font.</value>
public string FontName
{
get
{
return (string)GetValue(FontNameProperty);
}
set
{
SetValue(FontNameProperty, value);
}
}
/// <summary>
/// Gets the text.
/// </summary>
/// <value>The text.</value>
public string Text
{
get
{
return this.Checked
? (string.IsNullOrEmpty(this.CheckedText) ? this.DefaultText : this.CheckedText)
: (string.IsNullOrEmpty(this.UncheckedText) ? this.DefaultText : this.UncheckedText);
}
}
/// <summary>
/// Called when [checked property changed].
/// </summary>
/// <param name="bindable">The bindable.</param>
/// <param name="oldvalue">if set to <c>true</c> [oldvalue].</param>
/// <param name="newvalue">if set to <c>true</c> [newvalue].</param>
private static void OnCheckedPropertyChanged(BindableObject bindable, bool oldvalue, bool newvalue)
{
var checkBox = (CheckBox)bindable;
checkBox.Checked = newvalue;
}
private void NotifyPropertyChanged(string propertyName)
{
if (PropertyChanged != null)
{
PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
}
}
}
我有默认文本可绑定属性，我想通过Binding设置来自即将到来的Web服务的值。
我在Xaml上尝试的代码如下;
<uikit:CheckBox x:Name="CheckBox" WidthRequest="250" HeightRequest="100" FontSize="13" DefaultText="{Binding FirstText,Mode=TwoWay}" CheckedChanged="CheckBox_Clicked" TextColor="#263238" />
我无法这样做...我尝试在Xaml和Codebehind中设置绑定上下文。
我做错了什么？
你能帮我吗？
我还添加了PropertyChanged事件处理程序，我的更新代码如上所述。它仍然没有更新。
BR，
答案 0 :(得分：1)
在最后添加
public void RaiseCheckedChanged (bool val)
{
if (CheckedChanged != null)
CheckedChanged (this, new EventArgs<bool> (val));
}
并在同一个文件中添加此类
public class EventArgs<T> : EventArgs
{
/// <summary>
/// Initializes a new instance of the <see cref="EventArgs"/> class.
/// </summary>
/// <param name="value">Value of the argument</param>
public EventArgs(T value)
{
this.Value = value;
}
/// <summary>
/// Gets the value of the event argument
/// </summary>
public T Value { get; private set; }
}
public static class BindableObjectExtensions
{
/// <summary>
/// Gets the value.
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="bindableObject">The bindable object.</param>
/// <param name="property">The property.</param>
/// <returns>T.</returns>
public static T GetValue<T>(this BindableObject bindableObject, BindableProperty property)
{
return (T)bindableObject.GetValue(property);
}
}
public static class EventExtensions
{
/// <summary>
/// Raise the specified event.
/// </summary>
/// <param name="handler">Event handler.</param>
/// <param name="sender">Sender object.</param>
/// <param name="value">Argument value.</param>
/// <typeparam name="T">The value type.</typeparam>
public static void Invoke<T>(this EventHandler<EventArgs<T>> handler, object sender, T value)
{
var handle = handler;
if (handle != null)
{
handle(sender, new EventArgs<T>(value));
}
}
/// <summary>
/// Tries the invoke.
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="handler">The handler.</param>
/// <param name="sender">The sender.</param>
/// <param name="args">The arguments.</param>
/// <returns><c>true</c> if XXXX, <c>false</c> otherwise.</returns>
public static bool TryInvoke<T>(this EventHandler<T> handler, object sender, T args) where T : EventArgs
{
var handle = handler;
if (handle == null) return false;
handle(sender, args);
return true;
}
}