private static void RefreshBinding(AvaloniaObject target, AvaloniaProperty property)
{
if (target.GetValue(property) is IBinding binding)
{
target.Bind(property, binding);
}
}
/// <summary>
/// Initializes a new binding.
/// </summary>
/// <param name="avaloniaObject">The <see cref="AvaloniaObject"/> to apply the new binding to.</param>
/// <param name="avaloniaProperty">The <see cref="AvaloniaProperty{TValue}"/> the new binding should be applied to.</param>
/// <param name="defaultValue">The default value of the <paramref name="avaloniaProperty"/> at <c>1.0</c> scaling.</param>
public virtual void Initialize(AvaloniaObject avaloniaObject, AvaloniaProperty <T> avaloniaProperty, T defaultValue)
{
if (!isInitialized)
{
subscription = avaloniaObject.Bind(avaloniaProperty, source);
DefaultValue = defaultValue;
isInitialized = true;
}
}
private void AddBinding <T>(string modelFieldName,
AvaloniaObject control,
AvaloniaProperty <T> property,
bool isTwoWayDataBinding = false)
{
// (ideas from here)[http://avaloniaui.net/docs/binding/binding-from-code]
var bindingSource = new Subject <T>();
control.Bind <T>(property, bindingSource.AsObservable());
bool bindingIsDataContext = false;
object dataContext = null;
// does model contain a datacontext???
if (this.Model.HasKey(SpecialModelKeys.DataContext))
{
// bind to the data context
dataContext = this.Model[SpecialModelKeys.DataContext];
if (dataContext is System.ComponentModel.INotifyPropertyChanged prop)
{
// It's INotifyPropertyChanged so set this as handled
bindingIsDataContext = true;
// need to fire it's current value. Then start watching for changes
var currentValue = getDataContextValue(dataContext, modelFieldName);
log.Debug(
$"AddBinding-Model Value Change [*Initial* Field: {modelFieldName}; New Value: {currentValue}]");
FireOnNextWithValue <T>(bindingSource, currentValue);
prop.PropertyChanged += (_s, _args) => {
if (string.Equals(_args.PropertyName, modelFieldName, StringComparison.OrdinalIgnoreCase))
{
var newCurrentValue = getDataContextValue(dataContext, modelFieldName);
log.Debug($"AddBinding-Model Value Change [Field: {modelFieldName}; New Value: {newCurrentValue}]");
FireOnNextWithValue <T>(bindingSource, newCurrentValue);
}
};
}
else
{
/*
* !!REMEMBER!! You can use the bindabledictionary
* If you don't want to go to the trouble of implementing INotifyPropertyChanged just have your items use BindableDictionary and it's pretty easy
*/
throw new Exception(
$"Special DataContext used in model, but DataContext is not INotifyPropertyChanged. [modelFileName: {modelFieldName}] Type given is {dataContext?.GetType().Name ?? "null"}. There is no way to read properties without INotifyPropertyChanged");
}
}
if (!bindingIsDataContext)
{
notifyOnModelChange(modelFieldName, (val) =>
{
FireOnNext <T>(bindingSource, modelFieldName);
});
}
// If they say two way then we setup a watch on the property observable and apply the values back to the model
if (isTwoWayDataBinding)
{
// monitor for Property changes on control
var controlValueChangesObservable = control.GetObservable(property);
controlValueChangesObservable.Subscribe(newVal =>
{
if (newVal == null)
{
// there is never a situation where the UI would need to make a model property null right???
return;
}
log.Debug($"AddBinding-TwoWay-Control Value Change [Control Property: {property.Name}; Field: {modelFieldName}; New Value: {newVal}]");
setModelValue(modelFieldName, newVal);
});
}
// end of AddBinding
}
