Child 属性更新调用它是 parent 的 `OnPropertyChanged`
Child properties update calling it's parent's `OnPropertyChanged`
我正在尝试创建一个 XF 组件,其某些属性属于从 BindableObject
继承的类型。为了说明,我有 class Shadow
和 double Radius
和 Color ShadowColor
属性和 class MyBoxText
,它们有 bool IsLoading
和Shadow Ghost
个属性。
我的 View
和它的 Bindings
按预期工作,但我的自定义渲染器有问题:
当我更改 Ghost
属性时,我需要重绘整个视图(MyBoxText
控件),例如,以视觉方式更新阴影颜色。
这是一些微博:
类代码:
public class MyBoxText : Label /* It's bindable by inheritance */
{
#region Properties
public static readonly BindableProperty IsLoadingProperty = BindableProperty.Create(nameof(IsLoading), typeof(bool), typeof(MyBoxText), false) ;
public bool IsLoading
{
get { return (bool)GetValue(IsLoadingProperty); }
set { SetValue(IsLoadingProperty, value); }
}
public static readonly BindableProperty GhostProperty = BindableProperty.Create(nameof(Ghost), typeof(Shadow), typeof(MyBoxText), null) ;
public Shadow Ghost
{
get { return (Shadow)GetValue(GhostProperty); }
set { SetValue(GhostProperty, value); }
}
#endregion
}
public class Shadow : BindableObject /* It's explictly bindable */
{
#region Properties
public static readonly BindableProperty ShadowColorProperty = BindableProperty.Create(nameof(ShadowColor), typeof(Color), typeof(Shadow), Color.Black) ;
public Color ShadowColor
{
get { return (Color)GetValue(ShadowColorProperty); }
set { SetValue(ShadowColorProperty, value); }
}
public static readonly BindableProperty ShadowRadiusProperty = BindableProperty.Create(nameof(ShadowRadius), typeof(double), typeof(Shadow), 20) ;
public double ShadowRadius
{
get { return (double)GetValue(ShadowRadiusProperty); }
set { SetValue(ShadowRadiusProperty, value); }
}
#endregion
public Shadow()
{
}
}
我的渲染器代码是这样的:
public class MyBoxText : LabelRenderer
{
public MyBoxText()
{
SetWillNotDraw(false);
}
public override void Draw(Canvas canvas)
{
MyBoxText myView = (MyBoxText)this.Element;
// Some drawing logic
}
protected override void OnElementPropertyChanged(object sender, PropertyChangedEventArgs e)
{
base.OnElementPropertyChanged(sender, e);
if (e.PropertyName == MyBoxText.IsLoadingProperty.PropertyName ||
e.PropertyName == MyBoxText.GhostProperty.PropertyName )
Invalidate();
}
}
问题是,当我更改 Ghost.ShadowColor
属性 时,我的 'OnElementPropertyChanged' 覆盖没有被调用,并且视图在屏幕上保持旧颜色。
有没有办法将 child 的 'Property Update' 事件传播到 parent 视图 'Property Changed' 或其他实现此目的的方法?
The issue is that when I change the Ghost.ShadowColor property my 'OnElementPropertyChanged' override is not called, and the View stays with the old color on the screen.
Is there a way to propagate the child's 'Property Update' event to parent view 'Property Changed' or another way to achieve this?
是的,有办法。由于您的 Shadow 继承自 BindableObject
,它实现了 INotifyPropertyChanged
接口。您可以设置通知 ShadowColor
更改:
将 OnPropertyChanged()
添加到 Shadow.cs 中 ShadowColor
的 Setter:
public class Shadow : BindableObject /* It's explictly bindable */
{
#region Properties
public static readonly BindableProperty ShadowColorProperty = BindableProperty.Create(nameof(ShadowColor), typeof(Color), typeof(Shadow), Color.Black);
public Color ShadowColor
{
get { return (Color)GetValue(ShadowColorProperty); }
set { SetValue(ShadowColorProperty, value);
//Notify the ShadowColorProperty Changed
OnPropertyChanged();
}
}
...
}
像这样修改你的MyBoxText.cs
:
public class MyBoxText : Label /* It's bindable by inheritance */
{
...
public static readonly BindableProperty GhostProperty = BindableProperty.Create(nameof(Ghost), typeof(Shadow), typeof(MyBoxText), null);
public Shadow Ghost
{
get { return (Shadow)GetValue(GhostProperty); }
set {
//register the ShadowColor change event
value.PropertyChanged += ShadowColor_PropertyChanged;
SetValue(GhostProperty, value); }
}
private void ShadowColor_PropertyChanged(object sender, System.ComponentModel.PropertyChangedEventArgs e)
{
//unregister the event
this.Ghost.PropertyChanged -= ShadowColor_PropertyChanged;
//set this.Ghost to a new object with new ShadowColor to trigger the OnPropertyChanged
this.Ghost = new Shadow
{
ShadowColor = (sender as Shadow).ShadowColor,
ShadowRadius = Ghost.ShadowRadius
};
}
}
感谢 Elvis 的回答,我明白了。根据他的想法,我做了一些更改以在其他组件上重用它,我现在分享它以防其他人需要这样的东西。
我认为这样使用它我们可以获得更清晰和简单的代码:
public class MyBoxText : Label /* It's bindable by inheritance */
{
// Added this as private property
private ChangingPropagator changingPropagator;
private ChangingPropagator ChangingPropagator
{
get
{
if (changingPropagator == null)
changingPropagator = new ChangingPropagator(this, OnPropertyChanged, nameof(Shadow.ShadowColor), nameof(Shadow.ShadowRadius));
return changingPropagator;
}
}
#region Properties
public static readonly BindableProperty IsLoadingProperty = BindableProperty.Create(nameof(IsLoading), typeof(bool), typeof(MyBoxText), false) ;
public bool IsLoading
{
get { return (bool)GetValue(IsLoadingProperty); }
set { SetValue(IsLoadingProperty, value); }
}
public static readonly BindableProperty GhostProperty = BindableProperty.Create(nameof(Ghost), typeof(Shadow), typeof(MyBoxText), null) ;
public Shadow Ghost
{
// Here I use the ChangingPropagator's Getter and Setter instead of the deafult ones:
get { return ChangingPropagator.GetValue<Shadow>(GhostProperty); }
set { ChangingPropagator.SetValue(GhostProperty,ref value); }
}
#endregion
}
这是 ChangingPropagator
class:
public class ChangingPropagator
{
string[] listenedProperties = new string[0];
Action<string> changesNotifyer = null;
BindableObject propagationRootObject = null;
List<KeyValuePair<string, object>> propagationProperties = new List<KeyValuePair<string, object>>();
public ChangingPropagator(BindableObject bindableObject, Action<string> onPropertyChangedMethod, params string[] propertyToListenTo)
{
changesNotifyer = onPropertyChangedMethod;
propagationRootObject = bindableObject;
listenedProperties = propertyToListenTo ?? listenedProperties;
// ToDo: Add some consistency checks
}
public void AddPropertyToListenTo(params string[] propertyName)
{
listenedProperties = listenedProperties.Union(propertyName).ToArray();
}
// I need handle it here too 'cause when I use the child `Ghost` property coming from XAML binding, it didn't hit the `set` method
public T GetValue<T>(BindableProperty property)
{
var value = propagationRootObject?.GetValue(property);
if (value != null)
{
INotifyPropertyChanged bindableSubObject = (value as INotifyPropertyChanged);
if (bindableSubObject != null)
{
bindableSubObject.PropertyChanged -= PropagatorListener;
bindableSubObject.PropertyChanged += PropagatorListener;
if (!propagationProperties.Any(a => a.Key == property.PropertyName))
propagationProperties.Add(new KeyValuePair<string, object>(property.PropertyName, value));
}
}
return (T)value;
}
public void SetValue<T>(BindableProperty property, ref T value)
{
var oldValue = propagationRootObject?.GetValue(property);
if (oldValue != null)
{
INotifyPropertyChanged bindableSubObject = (value as INotifyPropertyChanged);
if (bindableSubObject != null)
bindableSubObject.PropertyChanged -= PropagatorListener;
}
if (value != null)
{
INotifyPropertyChanged bindableSubObject = (value as INotifyPropertyChanged);
if (bindableSubObject != null)
{
bindableSubObject.PropertyChanged += PropagatorListener;
propagationProperties.RemoveAll(p => p.Key == property.PropertyName);
propagationProperties.Add(new KeyValuePair<string, object>(property.PropertyName, value));
}
}
propagationRootObject.SetValue(property, value);
}
private void PropagatorListener(object sender, PropertyChangedEventArgs e)
{
if (listenedProperties?.Contains(e.PropertyName) ?? true)
PropagationThrower(sender);
}
private void PropagationThrower(object sender)
{
if (propagationProperties.Any(p => p.Value == sender))
{
var prop = propagationProperties.FirstOrDefault(p => p.Value == sender);
changesNotifyer?.Invoke(prop.Key);
}
}
}
我正在尝试创建一个 XF 组件,其某些属性属于从 BindableObject
继承的类型。为了说明,我有 class Shadow
和 double Radius
和 Color ShadowColor
属性和 class MyBoxText
,它们有 bool IsLoading
和Shadow Ghost
个属性。
我的 View
和它的 Bindings
按预期工作,但我的自定义渲染器有问题:
当我更改 Ghost
属性时,我需要重绘整个视图(MyBoxText
控件),例如,以视觉方式更新阴影颜色。
这是一些微博:
类代码:
public class MyBoxText : Label /* It's bindable by inheritance */
{
#region Properties
public static readonly BindableProperty IsLoadingProperty = BindableProperty.Create(nameof(IsLoading), typeof(bool), typeof(MyBoxText), false) ;
public bool IsLoading
{
get { return (bool)GetValue(IsLoadingProperty); }
set { SetValue(IsLoadingProperty, value); }
}
public static readonly BindableProperty GhostProperty = BindableProperty.Create(nameof(Ghost), typeof(Shadow), typeof(MyBoxText), null) ;
public Shadow Ghost
{
get { return (Shadow)GetValue(GhostProperty); }
set { SetValue(GhostProperty, value); }
}
#endregion
}
public class Shadow : BindableObject /* It's explictly bindable */
{
#region Properties
public static readonly BindableProperty ShadowColorProperty = BindableProperty.Create(nameof(ShadowColor), typeof(Color), typeof(Shadow), Color.Black) ;
public Color ShadowColor
{
get { return (Color)GetValue(ShadowColorProperty); }
set { SetValue(ShadowColorProperty, value); }
}
public static readonly BindableProperty ShadowRadiusProperty = BindableProperty.Create(nameof(ShadowRadius), typeof(double), typeof(Shadow), 20) ;
public double ShadowRadius
{
get { return (double)GetValue(ShadowRadiusProperty); }
set { SetValue(ShadowRadiusProperty, value); }
}
#endregion
public Shadow()
{
}
}
我的渲染器代码是这样的:
public class MyBoxText : LabelRenderer
{
public MyBoxText()
{
SetWillNotDraw(false);
}
public override void Draw(Canvas canvas)
{
MyBoxText myView = (MyBoxText)this.Element;
// Some drawing logic
}
protected override void OnElementPropertyChanged(object sender, PropertyChangedEventArgs e)
{
base.OnElementPropertyChanged(sender, e);
if (e.PropertyName == MyBoxText.IsLoadingProperty.PropertyName ||
e.PropertyName == MyBoxText.GhostProperty.PropertyName )
Invalidate();
}
}
问题是,当我更改 Ghost.ShadowColor
属性 时,我的 'OnElementPropertyChanged' 覆盖没有被调用,并且视图在屏幕上保持旧颜色。
有没有办法将 child 的 'Property Update' 事件传播到 parent 视图 'Property Changed' 或其他实现此目的的方法?
The issue is that when I change the Ghost.ShadowColor property my 'OnElementPropertyChanged' override is not called, and the View stays with the old color on the screen. Is there a way to propagate the child's 'Property Update' event to parent view 'Property Changed' or another way to achieve this?
是的,有办法。由于您的 Shadow 继承自 BindableObject
,它实现了 INotifyPropertyChanged
接口。您可以设置通知 ShadowColor
更改:
将
OnPropertyChanged()
添加到 Shadow.cs 中ShadowColor
的 Setter:public class Shadow : BindableObject /* It's explictly bindable */ { #region Properties public static readonly BindableProperty ShadowColorProperty = BindableProperty.Create(nameof(ShadowColor), typeof(Color), typeof(Shadow), Color.Black); public Color ShadowColor { get { return (Color)GetValue(ShadowColorProperty); } set { SetValue(ShadowColorProperty, value); //Notify the ShadowColorProperty Changed OnPropertyChanged(); } } ... }
像这样修改你的
MyBoxText.cs
:public class MyBoxText : Label /* It's bindable by inheritance */ { ... public static readonly BindableProperty GhostProperty = BindableProperty.Create(nameof(Ghost), typeof(Shadow), typeof(MyBoxText), null); public Shadow Ghost { get { return (Shadow)GetValue(GhostProperty); } set { //register the ShadowColor change event value.PropertyChanged += ShadowColor_PropertyChanged; SetValue(GhostProperty, value); } } private void ShadowColor_PropertyChanged(object sender, System.ComponentModel.PropertyChangedEventArgs e) { //unregister the event this.Ghost.PropertyChanged -= ShadowColor_PropertyChanged; //set this.Ghost to a new object with new ShadowColor to trigger the OnPropertyChanged this.Ghost = new Shadow { ShadowColor = (sender as Shadow).ShadowColor, ShadowRadius = Ghost.ShadowRadius }; } }
感谢 Elvis 的回答,我明白了。根据他的想法,我做了一些更改以在其他组件上重用它,我现在分享它以防其他人需要这样的东西。
我认为这样使用它我们可以获得更清晰和简单的代码:
public class MyBoxText : Label /* It's bindable by inheritance */
{
// Added this as private property
private ChangingPropagator changingPropagator;
private ChangingPropagator ChangingPropagator
{
get
{
if (changingPropagator == null)
changingPropagator = new ChangingPropagator(this, OnPropertyChanged, nameof(Shadow.ShadowColor), nameof(Shadow.ShadowRadius));
return changingPropagator;
}
}
#region Properties
public static readonly BindableProperty IsLoadingProperty = BindableProperty.Create(nameof(IsLoading), typeof(bool), typeof(MyBoxText), false) ;
public bool IsLoading
{
get { return (bool)GetValue(IsLoadingProperty); }
set { SetValue(IsLoadingProperty, value); }
}
public static readonly BindableProperty GhostProperty = BindableProperty.Create(nameof(Ghost), typeof(Shadow), typeof(MyBoxText), null) ;
public Shadow Ghost
{
// Here I use the ChangingPropagator's Getter and Setter instead of the deafult ones:
get { return ChangingPropagator.GetValue<Shadow>(GhostProperty); }
set { ChangingPropagator.SetValue(GhostProperty,ref value); }
}
#endregion
}
这是 ChangingPropagator
class:
public class ChangingPropagator
{
string[] listenedProperties = new string[0];
Action<string> changesNotifyer = null;
BindableObject propagationRootObject = null;
List<KeyValuePair<string, object>> propagationProperties = new List<KeyValuePair<string, object>>();
public ChangingPropagator(BindableObject bindableObject, Action<string> onPropertyChangedMethod, params string[] propertyToListenTo)
{
changesNotifyer = onPropertyChangedMethod;
propagationRootObject = bindableObject;
listenedProperties = propertyToListenTo ?? listenedProperties;
// ToDo: Add some consistency checks
}
public void AddPropertyToListenTo(params string[] propertyName)
{
listenedProperties = listenedProperties.Union(propertyName).ToArray();
}
// I need handle it here too 'cause when I use the child `Ghost` property coming from XAML binding, it didn't hit the `set` method
public T GetValue<T>(BindableProperty property)
{
var value = propagationRootObject?.GetValue(property);
if (value != null)
{
INotifyPropertyChanged bindableSubObject = (value as INotifyPropertyChanged);
if (bindableSubObject != null)
{
bindableSubObject.PropertyChanged -= PropagatorListener;
bindableSubObject.PropertyChanged += PropagatorListener;
if (!propagationProperties.Any(a => a.Key == property.PropertyName))
propagationProperties.Add(new KeyValuePair<string, object>(property.PropertyName, value));
}
}
return (T)value;
}
public void SetValue<T>(BindableProperty property, ref T value)
{
var oldValue = propagationRootObject?.GetValue(property);
if (oldValue != null)
{
INotifyPropertyChanged bindableSubObject = (value as INotifyPropertyChanged);
if (bindableSubObject != null)
bindableSubObject.PropertyChanged -= PropagatorListener;
}
if (value != null)
{
INotifyPropertyChanged bindableSubObject = (value as INotifyPropertyChanged);
if (bindableSubObject != null)
{
bindableSubObject.PropertyChanged += PropagatorListener;
propagationProperties.RemoveAll(p => p.Key == property.PropertyName);
propagationProperties.Add(new KeyValuePair<string, object>(property.PropertyName, value));
}
}
propagationRootObject.SetValue(property, value);
}
private void PropagatorListener(object sender, PropertyChangedEventArgs e)
{
if (listenedProperties?.Contains(e.PropertyName) ?? true)
PropagationThrower(sender);
}
private void PropagationThrower(object sender)
{
if (propagationProperties.Any(p => p.Value == sender))
{
var prop = propagationProperties.FirstOrDefault(p => p.Value == sender);
changesNotifyer?.Invoke(prop.Key);
}
}
}