/// <summary>
/// Handler for TextContainer.Changed event.
/// </summary>
internal override void OnTextContainerChanged(object sender, TextContainerChangedEventArgs e)
{
bool resetText = false;
string newTextValue = null;
try
{
// if there are re-entrant changes, only raise public events
// after the outermost change completes
_changeEventNestingCount++;
// Ignore property changes that originate from OnTextPropertyChange.
if (!_isInsideTextContentChange)
{
_isInsideTextContentChange = true;
// Use a DeferredTextReference instead of calculating the new
// value now for better performance. Most of the time no
// one cares what the new value is, and loading our content into a
// string can be extremely expensive.
DeferredTextReference dtr = new DeferredTextReference(this.TextContainer);
_newTextValue = dtr;
SetCurrentDeferredValue(TextProperty, dtr);
}
}
finally
{
_changeEventNestingCount--;
if (_changeEventNestingCount == 0)
{
// when Text is data-bound, _newTextValue is converted from a
// deferred reference to a string. The binding writes the string
// back to the source, then computes a new value for Text (which
// may be different, either because the source normalizes the value
// or because of conversion and formatting). Usually this raises
// a change notification for Text, which brings the Text property and
// the text container into [....]. But this doesn't happen in one
// case: when the normalized value is the same as the original
// value for Text. The property engine thinks that Text hasn't
// changed, and doesn't raise the notification. It's true that
// Text hasn't changed, but we still need to update the text container,
// which now displays the wrong value.
// We detect that case by checking whether _newTextValue (the
// text container value) agrees with Text.
if (FrameworkCompatibilityPreferences.GetKeepTextBoxDisplaySynchronizedWithTextProperty())
{
newTextValue = _newTextValue as String;
resetText = (newTextValue != null && newTextValue != Text);
}
_isInsideTextContentChange = false;
_newTextValue = DependencyProperty.UnsetValue;
}
}
if (resetText)
{
// The text container holds a new value which round-trips to the
// old value of Text. We need to bring the text container into [....].
try
{
_newTextValue = newTextValue;
_isInsideTextContentChange = true;
++ _changeEventNestingCount;
OnTextPropertyChanged(newTextValue, Text);
}
finally
{
-- _changeEventNestingCount;
_isInsideTextContentChange = false;
_newTextValue = DependencyProperty.UnsetValue;
}
}
if (_changeEventNestingCount == 0)
{
// Let base raise the public TextBoxBase.TextChanged event.
base.OnTextContainerChanged(sender, e);
}
}
// if the DeferredTextReference is resolved to a string during the previous
// method, track that here
internal void OnDeferredTextReferenceResolved(DeferredTextReference dtr, string s)
{
if (dtr == _newTextValue)
{
_newTextValue = s;
}
}
/// <summary>
/// Handler for TextContainer.Changed event.
/// </summary>
internal override void OnTextContainerChanged(object sender, TextContainerChangedEventArgs e)
{
try
{
// if there are re-entrant changes, only raise public events
// after the outermost change completes
_changeEventNestingCount++;
// Ignore property changes that originate from OnTextPropertyChange.
if (!_isInsideTextContentChange)
{
_isInsideTextContentChange = true;
// Use a DeferredTextReference instead of calculating the new
// value now for better performance. Most of the time no
// one cares what the new value is, and loading our content into a
// string can be extremely expensive.
DeferredTextReference dtr = new DeferredTextReference(this.TextContainer);
_newTextValue = dtr;
SetCurrentDeferredValue(TextProperty, dtr);
}
}
finally
{
_changeEventNestingCount--;
if (_changeEventNestingCount == 0)
{
_isInsideTextContentChange = false;
_newTextValue = DependencyProperty.UnsetValue;
}
}
if (_changeEventNestingCount == 0)
{
// Let base raise the public TextBoxBase.TextChanged event.
base.OnTextContainerChanged(sender, e);
}
}