So che ho bisogno di chiamare RemoveValueChanged, ma non sono stato in grado di trovare un posto affidabile per chiamare questo. Sto imparando che probabilmente non ce n'è uno.Come posso correggere DependencyPropertyDescriptor AddValueChanged Memory Leak su AttachedBehavior?
Mi sembra di dover trovare un modo diverso per monitorare la modifica, quindi aggiungere un gestore utilizzando AddValueChanged. Sto cercando consigli sul modo migliore per raggiungere questo obiettivo. Ho visto la raccomandazione di utilizzare un PropertyChangedCallback nel PropertyMetadata, ma non sono sicuro di come farlo quando il mio TextBox e Adorner non sono statici. Inoltre, la proprietà IsFocused non è una proprietà Dependency creata nella mia classe.
Grazie.
public sealed class WatermarkTextBoxBehavior
{
private readonly TextBox m_TextBox;
private TextBlockAdorner m_TextBlockAdorner;
private WatermarkTextBoxBehavior(TextBox textBox)
{
if (textBox == null)
throw new ArgumentNullException("textBox");
m_TextBox = textBox;
}
#region Behavior Internals
private static WatermarkTextBoxBehavior GetWatermarkTextBoxBehavior(DependencyObject obj)
{
return (WatermarkTextBoxBehavior)obj.GetValue(WatermarkTextBoxBehaviorProperty);
}
private static void SetWatermarkTextBoxBehavior(DependencyObject obj, WatermarkTextBoxBehavior value)
{
obj.SetValue(WatermarkTextBoxBehaviorProperty, value);
}
private static readonly DependencyProperty WatermarkTextBoxBehaviorProperty =
DependencyProperty.RegisterAttached("WatermarkTextBoxBehavior",
typeof(WatermarkTextBoxBehavior), typeof(WatermarkTextBoxBehavior), new UIPropertyMetadata(null));
public static bool GetEnableWatermark(TextBox obj)
{
return (bool)obj.GetValue(EnableWatermarkProperty);
}
public static void SetEnableWatermark(TextBox obj, bool value)
{
obj.SetValue(EnableWatermarkProperty, value);
}
public static readonly DependencyProperty EnableWatermarkProperty =
DependencyProperty.RegisterAttached("EnableWatermark", typeof(bool),
typeof(WatermarkTextBoxBehavior), new UIPropertyMetadata(false, OnEnableWatermarkChanged));
private static void OnEnableWatermarkChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
if (e.OldValue != null)
{
var enabled = (bool)e.OldValue;
if (enabled)
{
var textBox = (TextBox)d;
var behavior = GetWatermarkTextBoxBehavior(textBox);
behavior.Detach();
SetWatermarkTextBoxBehavior(textBox, null);
}
}
if (e.NewValue != null)
{
var enabled = (bool)e.NewValue;
if (enabled)
{
var textBox = (TextBox)d;
var behavior = new WatermarkTextBoxBehavior(textBox);
behavior.Attach();
SetWatermarkTextBoxBehavior(textBox, behavior);
}
}
}
private void Attach()
{
m_TextBox.Loaded += TextBoxLoaded;
m_TextBox.TextChanged += TextBoxTextChanged;
m_TextBox.DragEnter += TextBoxDragEnter;
m_TextBox.DragLeave += TextBoxDragLeave;
m_TextBox.IsVisibleChanged += TextBoxIsVisibleChanged;
}
private void Detach()
{
m_TextBox.Loaded -= TextBoxLoaded;
m_TextBox.TextChanged -= TextBoxTextChanged;
m_TextBox.DragEnter -= TextBoxDragEnter;
m_TextBox.DragLeave -= TextBoxDragLeave;
m_TextBox.IsVisibleChanged -= TextBoxIsVisibleChanged;
}
private void TextBoxDragLeave(object sender, DragEventArgs e)
{
UpdateAdorner();
}
private void TextBoxDragEnter(object sender, DragEventArgs e)
{
m_TextBox.TryRemoveAdorners<TextBlockAdorner>();
}
private void TextBoxIsVisibleChanged(object sender, DependencyPropertyChangedEventArgs e)
{
UpdateAdorner();
}
private void TextBoxTextChanged(object sender, TextChangedEventArgs e)
{
var hasText = !string.IsNullOrEmpty(m_TextBox.Text);
SetHasText(m_TextBox, hasText);
}
private void TextBoxLoaded(object sender, RoutedEventArgs e)
{
Init();
}
#endregion
#region Attached Properties
public static string GetLabel(TextBox obj)
{
return (string)obj.GetValue(LabelProperty);
}
public static void SetLabel(TextBox obj, string value)
{
obj.SetValue(LabelProperty, value);
}
public static readonly DependencyProperty LabelProperty =
DependencyProperty.RegisterAttached("Label", typeof(string), typeof(WatermarkTextBoxBehavior));
public static Style GetLabelStyle(TextBox obj)
{
return (Style)obj.GetValue(LabelStyleProperty);
}
public static void SetLabelStyle(TextBox obj, Style value)
{
obj.SetValue(LabelStyleProperty, value);
}
public static readonly DependencyProperty LabelStyleProperty =
DependencyProperty.RegisterAttached("LabelStyle", typeof(Style),
typeof(WatermarkTextBoxBehavior));
public static bool GetHasText(TextBox obj)
{
return (bool)obj.GetValue(HasTextProperty);
}
private static void SetHasText(TextBox obj, bool value)
{
obj.SetValue(HasTextPropertyKey, value);
}
private static readonly DependencyPropertyKey HasTextPropertyKey =
DependencyProperty.RegisterAttachedReadOnly("HasText", typeof(bool),
typeof(WatermarkTextBoxBehavior), new UIPropertyMetadata(false));
public static readonly DependencyProperty HasTextProperty =
HasTextPropertyKey.DependencyProperty;
#endregion
private void Init()
{
m_TextBlockAdorner = new TextBlockAdorner(m_TextBox, GetLabel(m_TextBox), GetLabelStyle(m_TextBox));
UpdateAdorner();
DependencyPropertyDescriptor focusProp = DependencyPropertyDescriptor.FromProperty(UIElement.IsFocusedProperty, typeof(FrameworkElement));
if (focusProp != null)
{
focusProp.AddValueChanged(m_TextBox, (sender, args) => UpdateAdorner());
}
DependencyPropertyDescriptor containsTextProp = DependencyPropertyDescriptor.FromProperty(HasTextProperty, typeof(TextBox));
if (containsTextProp != null)
{
containsTextProp.AddValueChanged(m_TextBox, (sender, args) => UpdateAdorner());
}
}
private void UpdateAdorner()
{
if (GetHasText(m_TextBox) ||
m_TextBox.IsFocused ||
!m_TextBox.IsVisible)
{
// Hide the Watermark Label if the adorner layer is visible
m_TextBox.ToolTip = GetLabel(m_TextBox);
m_TextBox.TryRemoveAdorners<TextBlockAdorner>();
}
else
{
// Show the Watermark Label if the adorner layer is visible
m_TextBox.ToolTip = null;
m_TextBox.TryAddAdorner<TextBlockAdorner>(m_TextBlockAdorner);
}
}
}
Grazie per l'aiuto. Non so come ho perso questa risorsa! – scuba88
Questa soluzione non sembra funzionare per me, non sto ottenendo l'evento OnPropertyChanged da PropertyChangedNotifier –