/// <summary>
/// Sets the value of the property to the new value.
/// </summary>
/// <param name="container">The container of the <see cref="DependencyProperty"/>.</param>
/// <param name="changeCount">The change count of the current property.</param>
/// <param name="expression">The <see cref="DependencyExpression"/> which is assigned to the property or null if no expression is assigned.</param>
/// <param name="baseValue">The base value of the property.</param>
/// <param name="value">The current value of the property.</param>
/// <param name="newValue">The new value of the property.</param>
internal override void SetValue(DependencyObjectContainer container, ref Int16 changeCount, ref GenericEventHandler <IDependencyObject, PropertyChangedEventArgs <TProperty> > changeHandler, ref DependencyExpression expression, ref TProperty baseValue, ref TProperty value, TProperty newValue)
{
// Save previous change count, prevents issues when a ThreadAbortException is thrown
Int16 previousChangeCount = changeCount;
try
{
// Copy previous expression if set
DependencyExpression oldExpression = expression;
// Compare the new value with the existing base value to avoid redundant changes to the property value
if (!Object.Equals(newValue, baseValue))
{
// Increase change count
changeCount++;
// Get the typed owner
TOwner representedObject = (TOwner)container.RepresentedObject;
// Copy old value for change events
TProperty oldValue = value;
// Validate the property value and throw a exception if the value is invalid
if (_ValidationCallback?.Invoke(representedObject, newValue) == false)
{
throw new ArgumentException($"Property value '{newValue}' is invalid for property {OwnerType.Name}.{Name}");
}
// We can now set the new base value anyway
baseValue = newValue;
// Coerce value to enable early check for a property change
TProperty coercedValue = newValue;
// Optional early exit if coercing is enabled and coerced and old value are the same
if (_CoerceValueCallback == null || !Object.Equals(coercedValue = _CoerceValueCallback(representedObject, newValue), oldValue))
{
// Notify that the property owner that the property is changing
_ChangingCallback?.Invoke(representedObject, new PropertyChangingEventArgs <TProperty>(changeCount, this, oldValue));
// Assign the new value to the property
value = coercedValue;
// Create a change event args once to avoid unnecessary copies
PropertyChangedEventArgs <TProperty> args = new PropertyChangedEventArgs <TProperty>(changeCount, this, coercedValue, oldValue);
// Raise the property event when existing
_ChangedCallback?.Invoke(representedObject, args);
// Only raise the
if (changeCount == 1)
{
// Set the previous change count before raising the events, this prevents
changeCount = previousChangeCount;
// Raise the event on the property directly
changeHandler?.Invoke(representedObject, args);
// Raise the event on the owner object
container.OnPropertyChange(args);
}
}
}
// It does not matter if the value is different, the expression must be removed in case a value is set
if (oldExpression != null && expression == oldExpression)
{
// Set expression to null
expression = null;
// Raise the markup change event
container.OnExtensionChange(new PropertyExtensionChangedEventArgs(this, null, oldExpression.ExpressionTemplate));
}
}
finally
{
// Set the previous change count
changeCount = previousChangeCount;
}
}
/// <summary>
/// Coerces the current value of the dependency object.
/// </summary>
/// <param name="container">The container of the <see cref="DependencyProperty"/>.</param>
/// <param name="changeCount">The change count of the current property.</param>
/// <param name="expression">The <see cref="DependencyExpression"/> which is assigned to the property or null if no expression is assigned.</param>
/// <param name="baseValue">The base value of the property.</param>
/// <param name="value">The current value of the property.</param>
internal override void CoerceValue(DependencyObjectContainer container, ref Int16 changeCount, ref GenericEventHandler <IDependencyObject, PropertyChangedEventArgs <TProperty> > changeHandler, DependencyExpression expression, TProperty baseValue, ref TProperty value)
{
// Save previous change count, prevents issues when a ThreadAbortException is thrown
Int16 previousChangeCount = changeCount;
try
{
// Get the typed owner
TOwner representedObject = (TOwner)container.RepresentedObject;
// Store previous coerced value
TProperty oldValue = value;
// Coerce value to enable early check for a property change
TProperty coercedValue;
// Method should only work when we've something to coerce
if (_CoerceValueCallback != null && !Object.Equals(coercedValue = _CoerceValueCallback(representedObject, baseValue), oldValue))
{
// Increase change count
changeCount++;
// Notify that the property owner that the property is changing
_ChangingCallback?.Invoke(representedObject, new PropertyChangingEventArgs <TProperty>(changeCount, this, oldValue));
// Assign the new value to the property
value = coercedValue;
// Create a change event args once to avoid unnecessary copies
PropertyChangedEventArgs <TProperty> args = new PropertyChangedEventArgs <TProperty>(changeCount, this, coercedValue, oldValue);
// Raise the property event when existing
_ChangedCallback?.Invoke(representedObject, args);
// Only raise the
if (changeCount == 1)
{
// Set the previous change count before raising the events, this prevents
changeCount = previousChangeCount;
// Raise the event on the property directly
changeHandler?.Invoke(representedObject, args);
// Raise the event on the owner object
container.OnPropertyChange(args);
}
}
}
finally
{
// Set the previous change count
changeCount = previousChangeCount;
}
}
/// <summary> /// Coerces the current value of the dependency object. /// </summary> /// <param name="container">The container of the <see cref="DependencyProperty"/>.</param> /// <param name="changeCount">The change count of the current property.</param> /// <param name="expression">The <see cref="DependencyExpression"/> which is assigned to the property or null if no expression is assigned.</param> /// <param name="baseValue">The base value of the property.</param> /// <param name="value">The current value of the property.</param> internal abstract void CoerceValue(DependencyObjectContainer container, ref Int16 changeCount, ref GenericEventHandler <IDependencyObject, PropertyChangedEventArgs <TProperty> > changeHandler, DependencyExpression expression, TProperty baseValue, ref TProperty value);
