Binding to DependencyProperty of a UserControl - wpf

Question

I Create a TimeInput Control Like to Enter Time.
<TextBox Text="{Binding Path=Hours}" />
<TextBox IsReadOnly="True"
Focusable="False"
Text=":" />
<TextBox Text="{Binding Path=Minutes}" />
and
public int Hours {
get { return (int)this.GetValue(HoursProperty); }
set {
this.SetValue(HoursProperty, value);
this.OnPropertyChanged("Hours");
}
}
public static readonly DependencyProperty HoursProperty =
DependencyProperty.Register("Hours", typeof(int), typeof(UserControl1), new UIPropertyMetadata(0, new PropertyChangedCallback(OnHoursChanged)));
private static void OnHoursChanged(DependencyObject obj, DependencyPropertyChangedEventArgs e) {
if (obj != null) {
int newValue = (int)e.NewValue;
}
}
public int Minutes {
get { return (int)this.GetValue(MinutesProperty); }
set {
this.SetValue(MinutesProperty, value);
this.OnPropertyChanged("Minutes");
}
}
// Using a DependencyProperty as the backing store for Minutes. This enables animation, styling, binding, etc...
public static readonly DependencyProperty MinutesProperty =
DependencyProperty.Register("Minutes", typeof(int), typeof(UserControl1), new UIPropertyMetadata(0, new PropertyChangedCallback(OnMinutesChanged)));
private static void OnMinutesChanged(DependencyObject obj, DependencyPropertyChangedEventArgs e) {
if (obj != null) {
int newValue = (int)e.NewValue;
}
}
public Nullable<TimeSpan> Value {
get { return (Nullable<TimeSpan>)this.GetValue(ValueProperty); }
set {
this.SetValue(ValueProperty, value);
this.OnPropertyChanged("Value");
}
}
// Using a DependencyProperty as the backing store for Value. This enables animation, styling, binding, etc...
public static readonly DependencyProperty ValueProperty =
DependencyProperty.Register("Value", typeof(Nullable<TimeSpan>), typeof(UserControl1), new UIPropertyMetadata(null, new PropertyChangedCallback(OnValueChanged)));
private static void OnValueChanged(DependencyObject obj, DependencyPropertyChangedEventArgs e) {
if (obj != null) {
(obj as UserControl1).UpdateTime(e.NewValue as TimeSpan?);
}
}
public void UpdateTime(TimeSpan? newTimeSpan) {
if (newTimeSpan.HasValue) {
this.Hours = newTimeSpan.Value.Hours;
this.Minutes = newTimeSpan.Value.Minutes;
}
}
#region INotifyPropertyChanged Members
public event PropertyChangedEventHandler PropertyChanged;
protected void OnPropertyChanged(string name) {
PropertyChangedEventHandler handler = this.PropertyChanged;
if (handler != null) {
handler(this, new PropertyChangedEventArgs(name));
}
}
#endregion
While I use this on another UserControl and Bind to a Property It doesn't work and show values.
I use it like this:
<uc:UserControl1 Value="{Binding StartTime}"/>
and
public TimeSpan StartTime
{
get { return new Types.Time(Item.StartTime).ToTimeSpan(); }
set { Item.StartTime = new Types.Time(value).ToShort(); NotifyPropertyChanged("StartTime"); }
}
That Item is an entity read from database and bind and StartTime is short form of hhmm.

Answer 1

i have updated your code, with dependency properties you don't need fire the property changed event explicit.
public partial class UserControl1 : UserControl
{
public UserControl1() {
this.InitializeComponent();
}
public int Hours {
get { return (int)this.GetValue(HoursProperty); }
set { this.SetValue(HoursProperty, value); }
}
public static readonly DependencyProperty HoursProperty =
DependencyProperty.Register("Hours", typeof(int), typeof(UserControl1), new UIPropertyMetadata(0, new PropertyChangedCallback(OnHoursChanged)));
private static void OnHoursChanged(DependencyObject obj, DependencyPropertyChangedEventArgs e) {
var uc = obj as UserControl1;
if (uc != null && e.NewValue != e.OldValue) {
int newValue = (int)e.NewValue;
uc.TimeValue = new TimeSpan(newValue, uc.Minutes, 0);
}
}
public int Minutes {
get { return (int)this.GetValue(MinutesProperty); }
set { this.SetValue(MinutesProperty, value); }
}
// Using a DependencyProperty as the backing store for Minutes. This enables animation, styling, binding, etc...
public static readonly DependencyProperty MinutesProperty =
DependencyProperty.Register("Minutes", typeof(int), typeof(UserControl1), new UIPropertyMetadata(0, new PropertyChangedCallback(OnMinutesChanged)));
private static void OnMinutesChanged(DependencyObject obj, DependencyPropertyChangedEventArgs e) {
var uc = obj as UserControl1;
if (uc != null && e.NewValue != e.OldValue) {
int newValue = (int)e.NewValue;
uc.TimeValue = new TimeSpan(uc.Hours, newValue, 0);
}
}
public Nullable<TimeSpan> TimeValue {
get { return (Nullable<TimeSpan>)this.GetValue(ValueProperty); }
set { this.SetValue(ValueProperty, value); }
}
public static readonly DependencyProperty ValueProperty =
DependencyProperty.Register("TimeValue", typeof(Nullable<TimeSpan>), typeof(UserControl1), new UIPropertyMetadata(null, new PropertyChangedCallback(OnValueChanged)));
private static void OnValueChanged(DependencyObject obj, DependencyPropertyChangedEventArgs e) {
var uc = obj as UserControl1;
if (uc != null && e.NewValue != e.OldValue) {
uc.UpdateTime(e.NewValue as TimeSpan?);
}
}
public void UpdateTime(TimeSpan? newTimeSpan) {
if (newTimeSpan.HasValue) {
this.Hours = newTimeSpan.Value.Hours;
this.Minutes = newTimeSpan.Value.Minutes;
}
}
}
second, i think you use the StartTime property incorrect, use it as dependency property too, or implement INotifyPropertyChanged.
{
// .....
StartTime = new Types.Time(this.Item.StartTime).ToTimeSpan();
// .....
}
public static readonly DependencyProperty StartTimeProperty =
DependencyProperty.Register("StartTime", typeof(TimeSpan?), typeof(Window1), new PropertyMetadata(default(TimeSpan?), new PropertyChangedCallback(OnStartTimePropertyChanged)));
private static void OnStartTimePropertyChanged(DependencyObject dependencyObject, DependencyPropertyChangedEventArgs e) {
if(e.NewValue != e.OldValue) {
(dependencyObject as Window1).Item.StartTime = new Types.Time(e.NewValue).ToShort();
}
}
public TimeSpan? StartTime {
get { return (TimeSpan?)GetValue(StartTimeProperty); }
set { SetValue(StartTimeProperty, value); }
}
hope this helps

Answer 2

You should not have any other code then calling GetValue and SetValue inside getter and setter of dependency property. But this may not resolve you problem. If you want to call some code when value change then do that inside callback method instead of setter.